Type MVGC Voltage Regulating Relay Service Manual R8021G Service Manual Type MVGC Voltage Regulating Relay HANDLING OF ELECTRONIC EQUIPMENT A person's normal movements can easily generate electrostatic potentials of several thousand volts. Discharge of these voltages into semiconductor devices when handling electronic circuits can cause serious damage, which often may not be immediately apparent but the reliability of the circuit will have been reduced. The electronic circuits of ALSTOM T&D Protection & Control Ltd products are completely safe from electrostatic discharge when housed in the case. Do not expose them to the risk of damage by withdrawing modules unnecessarily. Each module incorporates the highest practicable protection for its semiconductor devices. However, if it becomes necessary to withdraw a module, the following precautions should be taken to preserve the high reliability and long life for which the equipment has been designed and manufactured. 1. Before removing a module, ensure that you are at the same electrostatic potential as the equipment by touching the case. 2. Handle the module by its front-plate, frame, or edges of the printed circuit board. Avoid touching the electronic components, printed circuit track or connectors. 3. Do not pass the module to any person without first ensuring that you are both at the same electrostatic potential. Shaking hands achieves equipotential. 4. Place the module on an antistatic surface, or on a conducting surface which is at the same potential as yourself. 5. Store or transport the module in a conductive bag. More information on safe working procedures for all electronic equipment can be found in BS5783 and IEC 60147-0F. If you are making measurements on the internal electronic circuitry of an equipment in service, it is preferable that you are earthed to the case with a conductive wrist strap. Wrist straps should have a resistance to ground between 500k – 10MΩ. If a wrist strap is not available, you should maintain regular contact with the case to prevent the build up of static. Instrumentation which may be used for making measurements should be earthed to the case whenever possible. ALSTOM T&D Protection & Control Ltd strongly recommends that detailed investigations on the electronic circuitry, or modification work, should be carried out in a Special Handling Area such as described in BS5783 or IEC 60147-0F. CONTENTS SAFETY SECTION 6 1 1.1 1.2 1.3 1.3.1 1.3.2 1.4 APPLICATION Operating Sequences Voltage regulating schemes Optional external connections Independent/parallel control Auto /non-auto Line drop compensation for parallel transformers 10 10 11 11 11 12 12 2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 2.11 SETTINGS Reference voltage setting, VS Deadband setting, ∆V % Initial delay setting Intertap delay Line drop compensation settings, VR and VXL Parallel compensating voltage, VC Load shedding Undervoltage and overvoltage supervision, VU and VO Overcurrent detector, IL Circulating current detector, IC Internal setting switches 15 15 15 16 16 16 17 17 17 17 18 18 3 INSTALLATION 19 4 4.1 4.2. 4.2.1 4.2.2 4.2.3 4.2.4 4.2.5 4.2.6 4.2.6.1 4.2.6.2 4.2.7 4.2.7.1 4.2.7.2 4.2.8 4.2.8.1 4.2.8.2 4.2.9 4.2.10 4.2.11 COMMISSIONING Commissioning preliminaries Commissioning tests Equipment and input requirements General Regulated voltage setting (VS) Percentage deviation (∆V%) = 1/2 percentage deadband width. Under voltage blocking (80% VS) Load shedding –3%, –6%, –9% of VS +3%, +1.5%, –1.5% of VS Time delays Initial time delay Inter tap time delay Line drop compensation Resistive compensation VR Reactive compensation VXL Parallel compensating voltage VC Supervision circuits Load check for MVGC relay 20 20 21 21 22 22 22 23 23 23 23 24 24 25 26 26 27 27 27 29 4 5 5.1 5.2 5.2.1 5.2.2 5.2.3 5.2.4 5.2.5 5.2.6 5.2.7 5.2.8 MAINTENANCE Preliminary checks Functional check using the self test facility Regulated voltage setting Deadband setting ∆V% Initial time delay Intertap time delay Undervoltage detector VU Overvoltage detector VO Fixed 80% undervoltage detector Alarm timer 30 30 30 30 31 31 31 31 31 31 32 6 6.1 6.2 6.3 6.3.1 6.3.2 6.3.3 6.3.4 6.3.5 6.3.6 6.3.7 6.3.8 6.3.9 6.4 PROBLEM ANALYSIS Servicing instructions Equipment and input requirements: Test procedure Regulated voltage setting VS Deadband setting ∆V% Initial delay Intertap delay Fixed 80% undervoltage blocking Line drop compensation Parallel compensating voltage, VC Load shedding/voltage boost Supervision circuits Re-calibration 32 32 32 32 32 33 33 34 34 34 35 35 35 37 7 COMMISSIONING TEST RECORD 39 REPAIR FORM 43 5 SAFETY SECTION This Safety Section should be read before commencing any work on the equipment. Health and safety The information in the Safety Section of the product documentation is intended to ensure that products are properly installed and handled in order to maintain them in a safe condition. It is assumed that everyone who will be associated with the equipment will be familiar with the contents of the Safety Section. Explanation of symbols and labels The meaning of symbols and labels which may be used on the equipment or in the product documentation, is given below. Caution: refer to product documentation Caution: risk of electric shock Protective/safety *earth terminal Functional *earth terminal. Note: this symbol may also be used for a protective/ safety earth terminal if that terminal is part of a terminal block or sub-assembly eg. power supply. *Note: The term earth used throughout the product documentation is the direct equivalent of the North American term ground. Installing, Commissioning and Servicing Equipment connections Personnel undertaking installation, commissioning or servicing work on this equipment should be aware of the correct working procedures to ensure safety. The product documentation should be consulted before installing, commissioning or servicing the equipment. Terminals exposed during installation, commissioning and maintenance may present a hazardous voltage unless the equipment is electrically isolated. If there is unlocked access to the rear of the equipment, care should be taken by all personnel to avoid electric shock or energy hazards. Voltage and current connections should be made using insulated crimp terminations to ensure that terminal block insulation requirements are maintained for safety. To ensure that wires are correctly terminated, the correct crimp terminal and tool for the wire size should be used. 6 Before energising the equipment it must be earthed using the protective earth terminal, or the appropriate termination of the supply plug in the case of plug connected equipment. Omitting or disconnecting the equipment earth may cause a safety hazard. The recommended minimum earth wire size is 2.5 mm2, unless otherwise stated in the technical data section of the product documentation. Before energising the equipment, the following should be checked: Voltage rating and polarity; CT circuit rating and integrity of connections; Protective fuse rating; Integrity of earth connection (where applicable) Equipment operating conditions The equipment should be operated within the specified electrical and environmental limits. Current transformer circuits Do not open the secondary circuit of a live CT since the high voltage produced may be lethal to personnel and could damage insulation. External resistors Where external resistors are fitted to relays, these may present a risk of electric shock or burns, if touched. Battery replacement Where internal batteries are fitted they should be replaced with the recommended type and be installed with the correct polarity, to avoid possible damage to the equipment. Insulation and dielectric strength testing Insulation testing may leave capacitors charged up to a hazardous voltage. At the end of each part of the test, the voltage should be gradually reduced to zero, to discharge capacitors, before the test leads are disconnected. Insertion of modules and pcb cards These must not be inserted into or withdrawn from equipment whilst it is energised, since this may result in damage. Fibre optic communication Where fibre optic communication devices are fitted, these should not be viewed directly. Optical power meters should be used to determine the operation or signal level of the device. 7 Older Products Electrical adjustments Equipments which require direct physical adjustments to their operating mechanism to change current or voltage settings, should have the electrical power removed before making the change, to avoid any risk of electric shock. Mechanical adjustments The electrical power to the relay contacts should be removed before checking any mechanical settings, to avoid any risk of electric shock. Draw out case relays Removal of the cover on equipment incorporating electromechanical operating elements, may expose hazardous live parts such as relay contacts. Insertion and withdrawal of extender cards When using an extender card, this should not be inserted or withdrawn from the equipment whilst it is energised. This is to avoid possible shock or damage hazards. Hazardous live voltages may be accessible on the extender card. Insertion and withdrawal of heavy current test plugs When using a heavy current test plug, CT shorting links must be in place before insertion or removal, to avoid potentially lethal voltages. Decommissioning and Disposal Decommissioning: The auxiliary supply circuit in the relay may include capacitors across the supply or to earth. To avoid electric shock or energy hazards, after completely isolating the supplies to the relay (both poles of any dc supply), the capacitors should be safely discharged via the external terminals prior to decommissioning. Disposal: It is recommended that incineration and disposal to water courses is avoided. The product should be disposed of in a safe manner. Any products containing batteries should have them removed before disposal, taking precautions to avoid short circuits. Particular regulations within the country of operation, may apply to the disposal of lithium batteries. 8 Technical Specifications Protective fuse rating The recommended maximum rating of the external protective fuse for this equipment is 16A, Red Spot type or equivalent, unless otherwise stated in the technical data section of the product documentation. Insulation class: IEC 61010-1: 1990/A2: 1995 Class I EN 61010-1: 1993/A2: 1995 Class I This equipment requires a protective (safety) earth connection to ensure user safety. Installation Category (Overvoltage): IEC61010-1: 1990/A2: 1995 Category III EN 61010-1: 1993/A2: 1995 Category III Distribution level, fixed installation. Equipment in this category is qualification tested at 5kV peak, 1.2/50µs, 500Ω, 0.5J, between all supply circuits and earth and also between independent circuits. Environment: IEC 61010-1: 1990/A2: 1995 Pollution degree 2 EN 61010-1: 1993/A2: 1995 Pollution degree 2 Compliance is demonstrated by reference to generic safety standards. Product safety: 73/23/EEC Compliance with the European Commission Low Voltage Directive. EN 61010-1: 1993/A2: 1995 EN 60950: 1992/A11: 1997 Compliance is demonstrated by reference to generic safety standards. 9 Section 1 1.1 APPLICATION Operating Sequences For a large voltage deviation outside the set deadband the tap changer is required to perform a multiple tap change sequence. Two main methods of controlling such a sequence using relay type MVGC 01 are as follows:Method 1 Voltage deviation Initial time delay T definite or inverse Inter-tap delay Tap change increment t t t V% VS Measuring VT VRR 1 Second initiating pulse at intervals set by inter-tap delay. Figure 1 This is the standard method and is suitable where rapid correction of large voltage deviations is required to give better regulation. The initial delay setting determines the delay in initiating any tap change sequence. After an initiating pulse of 1 second the inter-tap delay setting determines the delay between subsequent tap change initiations. This process continues until the system voltage is restored to within the deadband limits. Method 2 For this method a tap changer operated, normally closed contact is connected such as to interrupt the measuring voltage supply to terminal 17 and 18. This operates the 80% undervoltage inhibit circuitry to reset the initial delay timer during each tap change step and hence the inter-tap delay feature is not used, i.e. set for continuous, non-pulsing by setting intertap delay less than or equal to zero. The normally closed contact is usually operated by direct movement of the tap changer’s motor mechanism using the directional sequence switch. 10 Voltage deviation T1 is determined by deviation from VS setting T1 Measuring VT T1 Contact opens during tap changer operation VRR T1 Inter-tap delay ≤ 0 gives a non-pulsing output and is also suitable for continuous adjusting equipment. Initial delay of VRR set for definite time gives set time delay between each tap change initiation. T1 V% VS Figure 2 For inverse initial delays the time delay between tap changes gets progressively longer as the voltage deviation decreases. With definite initial delay settings the time delay between each tap change is the fixed initial delay setting. Method 2 rapidly corrects large voltage deviations, but greatly extends the total time the voltage remains outside the deadband and is suitable only where load conditions will tolerate this. 1.2 Voltage regulating schemes Where Method 2 is used to control a multiple tap change sequence then the relay’s undervoltage relay contact will operate during each tap change step. To avoid unwanted alarm signals the undervoltage contact may be used to initiate a time delayed auxiliary relay type MVUA (see Publication R6039) which is typically set for 12 seconds delay on operate. Relay types MVGC and MVUA are available connected together as a MIDOS scheme. 1.3 Optional external connections 1.3.1 Independent/parallel control Where transformers connected in parallel are controlled using the minimum circulating current principle, independent operation is selected by shorting the interconnecting pilot wires as below. 23 A 24 Figure 3 Contact A – OPEN CLOSED Contact B – OPEN CLOSED for parallel control for independent control when local lv OCB is closed when local lv OCB is open 11 B To pilot loop 1.3.2 Auto /non-auto Non-auto or manual control can be obtained by isolating the common terminal of the relay’s raise/lower output contacts. 1 MVGC Raise A 3 Common 5 Lower Figure 4 1.4 Line drop compensation for parallel transformers Where parallel transformers feed distribution lines and line drop compensation is required, it is sometimes necessary to parallel the line drop compensation (LDC) CT inputs of each relay in the scheme. This ensures that each relay measures a current which is proportional to the load current of the power transformer (PT) irrespective of the number of parallel transformers in the scheme. Therefore, when the number of transformers supplying the load changes, the LDC settings on the relay will not need to be adjusted. Traditionally, when paralleling LDC inputs, it was assumed that line load currents would split equally between paralleled LDC circuits as LDC impedances were considered large compared to the interconnecting lead resistances. The MVGC 01 has a LDC burden of 0.4 VA at rated current. This is insufficient to ensure that interconnecting lead resistances are neglible. Therefore, when the LDC circuits are paralleled, it is necessary to pad out the burden of the LDC circuits by use of an external resistor. It should be remembered that when the LDC input CTs are paralleled, the LDC circuits will not see any components of the circulating current between parallel transformers, therefore negative reactance compensation cannot be used to combat circulating current. Only the ‘pilot’ method of circulating current control or external means of control can be employed. The following notes demonstrate how the LDC CTs may be paralleled on an MVGC 01 relay. 2RL1 = Lead loop resistance between CT1 and AVR1 plus resistance of AVR circulating current CT input (terminals 25 and 26 of MVGC 01). XM1 = CT1 magnetising impedance which will be ignored due to its high value when CT is unsaturated. RCT1 = CT1 winding resistance. RL = Resistance of one lead between AVRs (including any interposing CTs). CT1 = Driving CT (T1 loaded). CT2 = Idling CT (T2 loaded). 2IL = Current flowing in line(s) fed by T1/T2 which creates line voltage drop, which is to be compensated for. 12 I1 27 I2 RL 27 2IL 2RL1 AVR1 (MVGC 01) RLDC 2RL2 XM1 CT1 XM2 CT2 RCT1 RLDC AVR2 (MVGC 01) RCT2 2IL 28 28 RL EQUIVALENT CIRCUIT DIAGRAM FOR 2 MVGC 01 RELAYS WITH PARALLELED LDC INPUTS. RLDC.(2RL+ RLDC) RLDC + (2RL + RLDC) RLDC I1 = 2IL . = 2IL RLDC = IL . . (RLDC.(2RL + RLDC) (RL + RLDC) (2X + 1) (X + 1) where X = RL RLDC Ideally I1 should equal IL (also I2 = IL), but since RL is not zero, I1 will exceed IL. The required value of X to bring I1 down to 1.05IL will be determined by: 1.05IL = IL (2X + 1) (X + 1) 1.05X + 1.05 = 2X + 1 0.05 = 0.95X X = 0.0526 Therefore we require X < 0.0526 for I1 < 1.05IL EXAMPLE 1. Application of two AVRs (5A rated), using 5A:0.5A interposing transformers to isolate the individual line CTs. Assume: RL RL 13 is equivalent to: RICT1 RICT2 RL' RICT2 5:0.5A 5:0.5A RL' 2(RICT2 + RL') 100 2RL = 2RICT1 + Therefore: (RICT2 + RL') 100 RL = RICT1 + MVGC 01 burden for LDC = 0.4 VA at In Therefore: 0.4 52 = 0.016Ω RLDC = and X= RL RLDC < 0.0526 Therefore: (RICT2 + RL') < 0.0526RLDC 100 or RLDC must be increased to RLDC' via a series resistor so that: RICT1 + RLDC' > 19 (RICT1 + eg. RICT1 RICT2 RL' RICT1 (RICT2 + RL')) 100 = 0.02 = 0.3 = 0.2 This gives: RLDC' > 19(0.02 +(0.03 + 0.2)) 100 > 0.475 RLDC' = RLDC + Rs Therefore: Rs > 0.475 – 0.016 > 0.46 Choose a value of 0.5Ω. 14 Required continuous current capability 2In = 10A Therefore minimum current rating = 50W and, allowing a 50% derating of the component, a 100W resistor is required. THEREFORE USE RS = 0.5Ω 100W. Note: Rs should withstand the maximum main CT secondary rms current for a minimum of three seconds. The maximum output of the main CTs should not exceed three times the steady state current through its connected burden and CT resistance to cause saturation. EXAMPLE 2. Application of 2 AVRs (1A rated) with direct paralleling RL = 50m 2.5mm2 Cu = 0.37Ω RLDC = 0.4 = 0.4 12 RL RLDC' X= < 0.0526 where RLDC' = RLDC + Rs RLDC' > 19RL RLDC' > 7.03 Therefore: Rs > 7.03 – 0.4 > 6.63 Choose a value of Rs = 6.8Ω. Required continuous rating = 2In = 2A Therefore required continuous power rating of Rs = 27.2 W. Allowing a minimum power derating of 50%, use a resistor rated at 75W. THEREFORE USE Rs = 6.8Ω 75 W Note: Section 2 SETTINGS Note: 2.1 See short time current withstand note given in example 1. All controls whether being used or not, should be set at some point within their calibrated range and not set to either end stop. Reference voltage setting, VS The reference voltage setting is selected by thumbwheel switches in 1.0 volt steps between 100 and 139 volts. 2.2 Deadband setting, ∆V % This is set such that the nominal tap step increment is typically between 50% and 80% of the set deadband width, depending on preferred practice. Tap step increment % = preferred ratio x set deadband width e.g. Nominal tap step increment = 1.4% Preferred ratio = 70% 15 1.4 x 100 = 2% of VS 70 = ±1% of set VS Deadband width = Hence ∆V % 2.3 Initial delay setting The time delay to initiate a tap change sequence is set by the initial delay setting and is continuously adjustable between 1.2 and 12 seconds or 12 and 120 seconds depending on the range selected. A setting switch determines either a definite or an inverse time characteristic. For inverse characteristic the set time delay defines the operating time delay at the edge of deadband, N = 1. Larger voltage deviations give correspondingly faster operating times as given by IDMT characteristic, Figure 5, in Publication R6021. initial delay setting N = Voltage deviation from VS in multiples of ∆V% setting = 1 defines edge of deadband Inverse operating time = Where N i.e. 2.4 N Intertap delay Where a multiple tap change sequence is required then the time delay between successive tapping outputs can be set between zero and 10 seconds. This is normally set to be slightly longer than the operating time of the tap changer mechanism. Setting the intertap delay to less than zero then the output contacts are non-pulsing as previously described in Section 1.1. 2.5 Line drop compensation settings, VR and VXL These controls are set such that the voltage at a point remote to the tap changing transformer can be regulated for varying load conditions. The resistive setting is continuously adjustable between 0 and 24 volts at rated current. The reactive setting is continuously adjustable between 0 and 24 volts, or 0 and 48 volts at rated current, depending on the range selected. 3.IP.R VT ratio Where IP R XL VT ratio VR = 3.IP.XL VT ratio primary rated current of line CT. resistive component of line impedance reactive component of line impedance ratio of primary to secondary voltages of line VT VXL = = = = = A switch is provided, allowing selection of reverse reactance for control of transformers connected in parallel. For reverse reactance control the settings are now as below: 3.IP.XT VXL (reverse) = VT ratio Where XT = reactance of transformer 3.IP R Cos Ø + XL Sin Ø + XT Sin Ø . VT ratio Cos Ø Where Cos Ø = power factor of load Now VR = 16 The above shows that the effective VR compensation can vary significantly for varying power factors. Reverse reactance control of parallel transformers is used where transformers are dissimilar or at different locations and the power factor variation is not too great. 2.6 Parallel compensating voltage, VC An alternative method of achieving stable control of paralleled transformers is to minimise the reactive circulating current IC. This is achieved by the introduction of a parallel compensation voltage setting VC which is proportional to IC. The VC setting is continuously adjustable between 0 and 24 volts, or 0 and 48 volts depending on the range selected, for reactive rated current applied to the circulating current inputs. The VC setting is determined during commissioning procedures such that optimum stability is obtained for paralleled transformers. An approximate setting is given by. VC = 3.IP.XT VT ratio Circulating current control using VC setting allows both resistive and reactive components of line drop compensation to be utilised and is independent of power factor variations. 2.7 Load shedding Three levels of load shedding or voltage targets are available, either –3%, –6% or –9% of VS or +3%, +1.5% or –1.5% of VS, the latter incorporating a 1.5% or 3% voltage boost. The required amount can be selected by either a local or remote switch and LED indication of the selected value is given on the relay. 2.8 Undervoltage and overvoltage supervision, VU and VO Independent controls are provided to detect undervoltage and overvoltage conditions. The settings are continuously variable over the following ranges: VU : 80 – 120 volts VO : 110 – 160 volts Independent output contacts are provided for each function. In addition, operation of the overvoltage detector blocks raise operations, to prevent excessive voltage on busbars local to the transformer. Similarly the undervoltage detector blocks lower operations thus defining the normal working limits of the transformer and only allowing tap changes in such a direction as to restore the regulated voltage. 2.9 Overcurrent detector, IL The overcurrent detector setting IL is continuously variable between 100% and 200% of INL. Where the total load current through a transformer exceeds this setting then an internal relay operates blocking both raise and lower operations thus preventing tap changer operation for fault or overload current through the transformer. Note: Plugs for INL and INC should both be set to the same value (1A or 5A). INL is selected as either 1A or 5A by the plug bridge on the front of the relay. 17 2.10 Circulating current detector, IC The excessive circulating current detector setting is continuously variable between 5% and 50% of IN. The detector can be used to operate where a given tap disparity is exceeded. Where required, operation of a blocking relay for both raise and lower operations can be selected by an internal setting switch. Another switch is provided, allowing the circulating current detector to operate an alarm output relay and operation can be either instantaneous or time delayed. A third switch can be used to prevent any alarm initiation from the IC circuits. Note: 2.11 Plugs for INL and INC should both be set to the same value (1A or 5A). INC is selected as either 1A or 5A by the plug bridge on the front of the relay. Internal setting switches Three internal setting switches are provided to give the following options: Switch Position A Position B S6 VO and VU settings are independent of selected load shedding VO and VU settings are reduced by selected load shedding factor S7 Indication only of excessive circulating current Excessive circulating current gives indication and also operates blocking relay to prevent tap change initiation S8 Excessive circulating current causes alarm relay to operate after time delay of 180 seconds Excessive circulating current causes instantaneous operation of alarm relay Note: S8 is only effective with S10 in position A S9 Out of dead band signal does not initiate 180 second timer Voltage out of dead band for > 180 seconds gives alarm output S10 Excessive circulating current operates the alarm as defined by the position of S8 Excessive circulating current does not operate the alarm The switches are found at the bottom of the relays pcb’s as follows: Switch PCB Location S6 S7 S8 S9 S10 ZJ0049 ZJ0044 ZJ0044 ZJ0044 ZJ0044 Bottom Bottom Bottom Bottom Bottom Note: centre front rear rear-front rear-middle Earlier relays are not fitted with the switches S9 and S10. On these relays S9 is effectively in position B and S10 is effectively in position A. 18 Section 3 INSTALLATION 3.1 Protective relays, although generally of robust construction, require careful treatment prior to installation and a wise selection of site. By observing a few simple rules the possibility of premature failure is eliminated and a high degree of reliability can be expected. 3.2 The relays are either despatched individually or as part of a panel/rack mounted assembly, in cartons specifically designed to protect them from damage. Relays should be examined immediately they are received to ensure that no damage has been sustained in transit. If damage due to rough handling is evident, a claim should be made to the transport company concerned immediately, and the nearest ALSTOM T&D Protection & Control Ltd representative should be promptly notified. Relays which are supplied unmounted and not intended for immediate installation should be returned to their protective polythene bags. 3.3 Care must be taken when unpacking and installing the relays so that none of the parts are damaged or their settings altered, and they must at all times be handled by skilled persons only. Relays should be examined for any wedges, clamps or rubber bands necessary to secure moving parts to prevent damage during transit and these should be removed after installation and before commissioning. Relays which have been removed from their cases should not be left in situations where they are exposed to dust or damp. This particularly applies to installations which are being carried out at the same time as constructional work. 3.4 If relays are not installed immediately upon receipt they should be stored in a place free from dust and moisture in their original cartons and where de-humidifier bags have been included in the packing they should be retained. The action of the dehumidifier crystals will be impaired if the bag has been exposed to ambient conditions and may be restored by gently heating the bag for about an hour, prior to replacing it in the carton. Dust which collects on a carton may, on subsequent unpacking, find its way into the relay; in damp conditions the carton and packing may become impregnated with moisture and the de-humidifying agent will lose its efficiency. Storage temperature –25°C to +70°C. 3.5 The installation should be clean, dry and reasonably free from dust and excessive vibration. The site should preferably be well illuminated to facilitate inspection. An outline diagram is normally supplied showing panel cut-outs and hole centres. For individually mounted relays these dimensions will also be found in publication R6018. Publication R7012 is a Parts Catalogue and Assembly Instructions. This document will be useful when individual relays are to be assembled as a composite rack or panel mounted assembly. 19 Section 4 4.1 COMMISSIONING Commissioning preliminaries Electrostatic Discharges (ESD) The relay uses components which are sensitive to electrostatic discharges. When handling the module, care should be taken to avoid contact with components and electrical connections. When removed from the case for storage, the module should be placed in an electrically conducting anti-static bag. See full recommendations inside the front cover of this manual. Inspection Carefully examine the module and case to see that no damage has occurred during transit. Check that the relay serial numbers on the module and case cover are identical and that the model number and rating information are correct. Wiring Check that the external wiring is correct to the relevant relay diagram or scheme diagram. The relay diagram number appears inside the case. Note that shorting switches shown on the relay diagram are fitted internally across the relevant case terminals and close when the module is withdrawn. It is essential that such switches are fitted across all CT circuits. Earthing Ensure that the case earthing connection above the rear terminal block is used to connect the relay to a local earth bar. Insulation The relay and its associated wiring, may be insulation tested between: – all electrically isolated circuits – all circuits and earth An electronic or brushless insulation tester should be used, having a dc voltage not exceeding 1000V. Accessible terminals of the same circuit should first be strapped together. Deliberate circuit earthing links, removed for the tests, subsequently must be replaced. Electrical tests Applicable to all relays involving current transformers: DANGER DO NOT OPEN CIRCUIT THE SECONDARY CIRCUIT OF A CURRENT TRANSFORMER SlNCE THE HIGH VOLTAGE PRODUCED MAY BE LETHAL AND COULD DAMAGE INSULATION. When type MMLG test block facilities are installed, it is important that the sockets in the type MMLBO1 test plug, which correspond to the current transformer secondary windings, are LINKED BEFORE THE TEST PLUG IS INSERTED INTO THE TEST BLOCK. Similarly, a MMLB02 single finger test plug must be terminated with an ammeter BEFORE IT IS INSERTED to monitor CT secondary currents. 20 Terminal allocation of relay Terminals of the relay are usually allocated as follows but not all relay applications will use all these terminals. Terminals 17, 18 Reference ac voltage, VN Auxiliary ac voltage, Vx 15, 14 13, 14 Input from line CT for line drop compensation 27, 28 Input from line CT for circulating current control 25, 26 (in series with 27, 28) Input from circulating current pilots 23, 24 Load shedding control contacts. (Internally connected to Vx circuit) Common –3% or +3% –6% or +1.5% –9% or –1.5% 22 19 20 21 Tap changer control contacts. Common Raise Lower 3 1 5 Output contacts: 4.2. (110/125V) (220/250V) Undervoltage Overvoltage 2&4 7&9 Alarm for voltage outside deadband for 3 minutes or for excessive circulating current either instantaneously or for 3 minutes 6&8 10 & 12 Commissioning tests Typical application diagrams are shown in Figures 8 and 9 4.2.1 Equipment and input requirements AC auxiliary supply suitable to supply a 30VA load. The frequency (Hz) must be the same as the Vx and Hz given on the module rating label mounted in the lower handle. The voltage must be set for the selected voltage input, ie. 110V for 110/120V input. Stable measuring ac voltage supply of rated frequency with a fine adjustment control to operate between 70 and 170 volts ac into a 3VA load. High accuracy TRMS ac voltmeter, ac voltage accuracy less than 0.1% at full range, 50 or 60Hz. Stopwatch or electronic timer Two pole switch and resistor (typically 5kΩ 2W). For testing the line drop compensator controls it is necessary to be able to phase shift the angle between the regulated voltage supply and the current. The following equipment is necessary: Three phase 440V supply Sinusoidal current source from 0 to 10 amps ac into a 10VA burden at rated current. Phase shifter (440/240V line to line) and an adjustable single phase voltage transformer (variac) to supply the regulated voltage supply. 21 Phase angle meter, accuracy better than 2°. AC ammeter, range 0 to 10 amps. 4.2.2 General Set all controls to the required settings. NOTE: The ‘tens’ thumbwheel switch on the VS setting control can be set to any number between 0 and 9, but positions 3 to 9 all produce the same setting of 3. If a test block is not used to isolate the normal VT, auxiliary, CT and any other supplies, ensure that there is no accidental connection of test and normal supplies and the CT is not open circuited. Check that the auxiliary ac supply is the correct voltage and wire to terminals 15 and 14 (110/125V) or to terminals 13 and 14 (220/250V). Wire the regulated voltage supply to terminals 17 and 18 and the high accuracy voltmeter either to the same terminals or to the monitor sockets on the front of the relay. 4.2.3 Regulated voltage setting (VS) Set the TEST/NORMAL switch to NORMAL. Energise the auxiliary voltage supply and check that the ‘Volts Low’ indicator lamp is lit. Energise the regulated voltage supply and adjust the voltage to the nominal setting voltage, as set on the VS thumbwheel switches. Check that the ‘Volts Low’, ‘Volts High’ and ‘Tap’ lamps are not lit. Slowly increase the regulated voltage supply until the ‘Volts High’ lamp just lights and note this voltage (VH). A fine control and accurate voltmeter are essential to establish this voltage with accuracy. Decrease the regulated supply and check that the ‘Volts High’ lamp goes out immediately. Continue lowering the voltage until the ‘Volts Low’ lamp just lights and note this voltage (VL). Actual voltage setting = 1/2 (VH + VL) volts Tolerance: ±0.5% NOTE: The above accuracy limit makes no allowance for instrument error and possible poor waveform which may be experienced during commissioning. In service it may be found necessary to change the setting voltage VS. It is therefore advisable to check all positions of the thumbwheel switches using the above procedure. This involves fourteen checks, ten for the units and four for the tens. NOTE: The tens switch cannot be set higher than 3. Reset VS to the required setting. 4.2.4 Percentage deviation (∆V%) = 1/2 percentage deadband width. Calculate the actual percentage deviation using the voltages VH and VL measured in the test above and the formula below. 1 Actual percentage deviation = (VH – VL) x 100% 2VS Tolerance: ±0.2 of the value set on the Percentage Deviation Control. 22 4.2.5 Under voltage blocking (80% VS) This is the voltage below which any further tap change initiation is prevented. The blocking voltage is checked most easily if the intertap time delay control is temporarily set below zero. This ensures that after the initial tap delay has elapsed the ‘raise’ or ‘lower’ auxiliary will stay operated when the voltage is outside the deadband. Reduce the voltage slightly below VL (as measured in the previous test) and check that the ‘Volts Low’ and ‘Tap’ lamps both light continuously. Continue lowering the voltage until the ‘Tap’ lamp is extinguished. This voltage should be 80% of VS (tolerance ±3%). Reset the intertap time delay to the required setting. 4.2.6 Load shedding The effective regulated voltage setting can be reduced by selected amounts by shorting the appropriate relay terminals. 4.2.6.1 –3%, –6%, –9% of VS Link terminal 22 to 19 and check that the 3% LED illuminates. Measure the new VH and VL and calculate the centre of dead band voltage. This should be 3% lower than the actual VS voltage previously measured. Link terminal 22 to 20 and check that the 6% LED illuminates. Measure the new VH and VL and calculate the centre of dead band voltage. This should be 6% lower than the actual VS voltage previously measured. Link terminal 22 to 21 and check that the 9% LED illuminates. Measure the new VH and VL and calculate the centre of dead band voltage. This should be 9% lower than the actual VS voltage previously measured. Remove the link after test 4.2.6.2 +3%, +1.5%, –1.5% of VS Link terminal 22 to 19 and check that the +3% LED illuminates. Measure the new VH and VL and calculate the centre of dead band voltage. This should be 1.5% lower than the actual VS voltage previously measured. Link terminal 22 to 20 and check that the +1.5% LED illuminates. Measure the new VH and VL and calculate the centre of dead band voltage. This should be 1.5% higher than the actual Vs voltage previously measured. Link terminal 22 to 21 and check that the –1.5% LED illuminates. Measure the new VH and VL and calculate the centre of dead band voltage. This should be 3% higher than the actual VS voltage previously measured. Remove the link after test 23 4.2.7 Time delays To measure accurately the time delays, it is necessary to be able to carry out a step change in voltage and start a timer at the same time. This can be conveniently done using a two pole switch, a resistor (say 5KΩ) and an electronic timer, see Figure 5 below. Alternatively the time may be checked, approximately, using a stopwatch. Timer Auxiliary ac supply Start 15 Adjustable stable voltage supply 13 17 14 1 5 V R 18 Timer stop 3 Circuit for timing tests Figure 5 4.2.7.1 Initial time delay Connect the relay as shown in 4.2.7. Switch the Inverse/Definite time switch to ‘Definite’. With the two pole switch open and the resistor in circuit adjust the voltage until it is inside the deadband, so that neither the ‘Volts Low’ or ‘Volts High’ lamp is illuminated. Close the switch and check that it: (a) starts the timer, (b) raises the voltage on the relay to above the VH value (measured in test 4.2.3) and (c) energises the ‘Volts High’ lamp. Also check that the ‘Lower’ contacts of the relay operate (Terminals 3 and 5) after the initial time delay set on the relay. NOTE: To obtain a consistent timing it is essential to ensure that the timer has reset after each timing. Removal of the stable voltage supply does this immediately. For 1.2–12s range, operating time should be 0.5s + setting. Tolerance –0 +0.8s or ±10% whichever is greater. For 12–120s range, operating time is as setting. Tolerance ±5%. Inverse time delay Switch the Inverse/Definite time switch to ‘Inverse’. In this position the initial time delay depends on how far the voltage deviates beyond the operating threshold (i.e. deadband edges). At the threshold the time should be as marked on the initial time delay scale. At other voltages the following formula applies: Expected tinitial = Initial time delay setting (% Voltage deviation from VS) /∆V% The inverse initial time delay may be checked at any reasonable voltage outside the deadband. The expected time may be calculated using the formula above. The procedure given below is for an example where the voltage increases from inside the deadband to a value higher than the setting voltage. 24 With the two pole switch open adjust the voltage until it is inside the deadband, so that neither the ‘Volts Low’ nor the ‘Volts High’ lamp is illuminated. Close the switch and: (a) check that it starts the timer (b) measure the voltage accurately (say VH) (c) check the operating time (as previous removal of the stable voltage supply between checks resets the timer). Calculate the “percentage voltage deviation from VS” which is (VH – VS) 100/VS. Calculate the expected tinitial from the formula given earlier. Calculate the error in operating time. For 1.2–12s range, operating time should be 0.5s + setting. Tolerance –0 +0.8s or ±20% whichever is greater. For 12 – 120s range, operating time is as setting. Tolerance ±20%. 4.2.7.2 Inter tap time delay When the applied voltage is first taken out of the deadband there will be the initial time delay and then the raise or lower output auxiliary and the ‘Tap’ lamp will be energised for 1 second ±0.2 seconds. When the auxiliary drops out there will be a time delay equal to the intertap time delay before the auxiliary relay operates. It will continue in this mode until the voltage is returned into the deadband. Note: If the intertap time delay potentiometer is set below zero there will be no time delay. Once the Raise or Lower auxiliary has been energised it will remain operated until the voltage returns inside the deadband. To measure the intertap time accurately it is necessary to use a timer which has ‘Dwell time’ facilities on it and will also start when the auxiliary relay contact opens and stop when the same contact closes. The timer will need to be reset during the 1 second during which the auxiliary relay contact is closed. Tolerance on the intertap time = ±10% The intertap time may be reasonably accurately measured by timing any convenient number of cycles with a stopwatch and then calculating the intertap time as follows: Intertap tap time = Time measured – number of cycles Number of cycles The initiation of the ‘Tap’ lamp in each cycle is a very convenient point from which to start and finish timing. 25 4.2.8 Line drop compensation For these circuits to operate correctly it is important to observe correct polarities for voltage and current connections. Figure 6 below gives a typical test connection circuit. A B C N Phase shifter a b c Auxiliary ac supply n 110V 120V 15 17 220V 250V 13 14 27 I MVGC V 18 28 Phase angle meter Figure 6 4.2.8.1 Resistive compensation VR With VR still on the required setting, set VC and VXL = 0. Apply rated current to terminals 27 and 28. Apply the reference voltage and adjust the phase angle until the voltage leads the current by 90°. Find the centre of deadband voltage as detailed previously for the regulated voltage setting VS. New values of VH and VL will be found and the centre of deadband voltage VH + VL = volts 2 This should be higher than the actual VS voltage measured earlier by the voltage set on the VR control. Tolerance ±0.5 volts or 5% whichever is the greater. NOTE: If the voltage is lower than the actual VS it is almost certain that there is an unintentional polarity reversal somewhere in the test circuit. 26 4.2.8.2 Reactive compensation VXL Using the above circuit reset VXL to the required setting and set VC and VR = 0. Set the Direct/Reverse switch to Direct. Apply rated current to terminals 27 and 28. Apply the reference voltage and adjust the phase angle until the voltage is in antiphase with the current. Measure the new VH and VL and calculate the centre of deadband voltage. This should be greater than the actual VS voltage measured earlier by the voltage set on the VXL control. If the relay is to be used with the Direct/Reverse switch in the Reverse position, check as above but with the voltage and current in phase. The voltage will again be higher by the voltage set on the VXL control. Tolerance ±0.5 volts or 5% whichever is the greater. 4.2.9 Parallel compensating voltage VC The relay is connected as for 4.2.8 except that the current source is connected to terminals 25 and 26. Ensure that the correct polarity is used (i.e. terminal 25 corresponding to the original connection to 27 and 26 to 28). The pilot connection terminals (23 and 24) which go to the relay on the other transformer circuit must be open circuited. Apply rated current to terminals 25 and 26. Apply the reference voltage and adjust the phase angle until the voltage is in phase with the current. Measure the new VH and VL and calculate the centre of the deadband voltage. This should be greater than the actual VS voltage measured originally, by the voltage set on the VC control. Tolerance ±0.5 volts or 5% whichever is the greater. Short circuit the pilot terminals 23 and 24 and measure VH and VL and calculate the centre of the deadband voltage. This should be unchanged from the Actual VS voltage measured originally. Remove the short circuit and reconnect terminals 23 and 24. 4.2.10 Supervision circuits (i) The undervoltage or overvoltage relays operate and energise the appropriate LED indication when the input voltage falls below the VU setting or rises above the VO setting. Note: On pcb ZJ0049 switch 6 (was LKl) makes VU and VO either independent of the load shedding (Position A or Link 1 between A and B) or dependent on the load shedding (Position B or Link 1 between A and C). Apply the actual setting voltage VS and check that neither the under or over voltage LED’s indicate. Reduce the voltage and check the value at which the <VU lamp indicates. Check that the under voltage output contact has closed to complete the circuit between terminals 2 and 4. Increase the voltage and note that the <VU lamp de-energises. 27 Further increase the voltage and check the value at which the >VO lamp indicates. Check that the overvoltage output contact has closed to complete the circuit between terminals 7 and 9. Tolerance for VO and VU ±10%. (ii) The overcurrent blocking relay operates when the total load current exceeds the IL setting. Monitor across terminals 3 and 5 to check when the lower volts contact closes. Apply the actual setting voltage VS and check that there is no circuit across 3 and 5. Increase the voltage until the relay operates and check that the circuit is complete. Apply current to terminals 27 and 28 and check the current at which the 3/5 circuit becomes open circuit. This current should correspond to the IL setting. Tolerance ±10%. A similar test may be carried out with the voltage low, monitor terminals 1 and 3 and recheck the IL current setting. (iii) The circulating current detector operates when the circulating current between transformers connected in parallel exceeds the current set on the IC setting potentiometers. Note: The calibration of the IC setting potentiometer is in terms of the CT secondary current. Wire a current source to terminals 25 and 26 with terminals 23 and 24 open circuited. Apply current and increase until the excessive circulating current lamp (>IC) indicates. This should be at the current set on the IC setting potentiometer. Tolerance ±10%. At the same time as the IC lamp is energised, the alarm circuit is initiated either instantaneously or after a 3 minute time delay. Switch 8 (was LK3) on pcb ZJ0044 gives alarm after 3 minutes when selected to position A (or Link 3 between A and B) or gives instantaneous alarm selected to position B (or link 3 between A and C). If S10 is fitted, position A gives normal operation as above and position B gives no operation of the alarm from excessive circulating currents. Check that when the circulating current exceeds IC, the alarm lamp operates and the alarm circuits on terminals 6 & 8 and 10 & 12 are completed either after 3 minutes or instantaneously depending on the position of switch 8 (LK3). Note: On pcb ZJ0044 switch 7 (was LK2) may be selected such that circulating current gives indication of the IC lamp only, (Position A or Link 2 between A and B) or that it gives indication and operates relay RL5 to prevent tap change initiation. (Position B or Link 2 between A and C). When in the position to prevent tap change the checks below should be carried out to check that tapping is prevented. Maintain sufficient current to keep the IC detector operated. Apply an adjustable voltage supply to terminals 17 and 18 and increase this until the voltage is inside the deadband (Volts Low and Volts High lamps will not be lit). 28 Monitor contact outputs 1 & 3 and 3 & 5 and check that there is no circuit. Reduce the voltage until the Volts Low lamp operates and check that after a suitable time delay the tap lamp indicates but that there is still no circuit on the contacts. Repeat with a higher voltage to operate the Volts High lamp. Remove the current injected into terminals 25 and 26. Adjust the voltage until it is inside the deadband and repeat the above procedure but check that output circuits 1 and 3 eventually close when the voltage is low, and that circuit 3 and 5 close when the voltage is high. (iv) The alarm output relay operates in approximately 3 minutes when the input voltage remains continuously outside the deadband limits. If S9 is fitted position B allows alarm operation, position A does not allow alarm operation. This may be satisfactorily checked using a stopwatch. Apply the actual setting voltage VS and check that none of the lamps indicate. Raise the voltage by approximately 10% and start a stopwatch as soon as the Volts High Lamp indicates. Stop the stopwatch when the alarm lamp indicates. The time should be between 180s and 216s. Monitor terminals 6 & 8 and 10 & 12 to check that the two contact pairs close when the alarm lamp lights. 4.2.11 Load check for MVGC relay When the line drop compensation facility is used it is essential to carry out a check with load down the line to prove that the polarities of the VT and CT as connected to the relay are correct. The results will be most conclusive if the load current is large. Calculate the expected R and X voltage drops in the line at the CT rated primary current and convert these to secondary values using the VT ratio. Set the VR and jVXL controls on the relay to these latter voltages. Set the ∆V% sensitivity setting to 3 and the switch below the jVXL control to ‘direct’. At the receiving end of the feeder measure accurately the phase to phase voltage on the secondary of the VT. This should be done (at the remote end) on the same pair of lines as those used by the relay at the sending end. Set the VS setting thumbwheel switches on the relay to the same voltage as that measured at the receiving end of the feeder. The relay should be inoperative under this condition, as indicated by an absence of the ‘volts high’ or ‘volts low’ lamps. If either lamp is illuminated, it is highly probable that either the CT or VT has been connected to the relay with the wrong polarity, or that the VR and jVXL relay settings are not correctly matched to the line. If the relay is inoperative for ∆V% = 3 then the approximate limits of the deadband or inoperative zone can be established as follows: Increase and then decrease the VS setting of the relay using the thumbwheel switches until either the ‘volts low’ or the ‘volts high’ lamp indicates. Record the two voltage settings at which the lamps first indicate. If the average of these two voltages is within say 2% of that measured at the remote end of the feeder, then the relative polarities of the CT and the VT are correct. 29 It will be appreciated that for this test to be conclusive the actual voltage drop down the line at the current level available must be well in excess of 2%. Reset the VS and ∆V% controls to the settings required for the particular application. Note: Section 5 All controls, whether being used or not, should be set at some point within their calibrated range and not set to either end-stop. MAINTENANCE Periodic maintenance is not required. However periodic inspection and test is recommended as follows: 5.1 Preliminary checks Loosen the four cover screws and remove the cover, the relay can now be withdrawn from its case. Check all wiring connections to the terminal block and to the pcb’s, paying particular attention to polarity of CT connections to the terminal block, terminal number 23 to 28 inclusive. Check that the positions of switches 6, 7 and 8, 9 and 10 are as required; these are described in Section 2.11. 5.2 Functional check using the self test facility Relay type MVGC has a self test facility which provides a variable measuring voltage supply allowing a functional check on all of the voltage operated circuits in the relay. Connect an ac voltmeter capable of measuring 160V rms to the sockets marked ‘voltage monitor’ on the front of the relay. With the test switch in ‘normal’ position the voltage indicated is the measuring voltage present at relay terminals 17 and 18. Selection of the ‘test’ position isolates the measuring voltage input and applies a voltage, set by the ‘test volts adjust’ potentiometer on front of the relay to the relay’s measuring input. This voltage is variable between 80V and 160V and can be used to check regulated voltage setting VS, deadband setting ∆V% as well as undervoltage and overvoltage supervision VU and VO. The test facility may also be used, along with a stopwatch, to check the relay’s timing functions. Use of the test facility still allows the relay to control the tap change mechanism. It may be desirable, however, before carrying out the checks listed below, to prevent tap change initiation by selecting manual/non-auto on the panel control switch. 5.2.1 Regulated voltage setting Connect ac voltmeter to ‘test volts’ sockets. Set test switch to ‘test’ position. Set desired VS on thumbwheel switches. Set V% to 0.5. Adjust ‘test volts’ potentiometer until both the volts high and the volts low LED’s are off (i.e. the voltage is inside the deadband). The indicated voltage should be approximately equal to the set VS. 30 5.2.2 Deadband setting ∆V% Adjustment of the ‘test volts’ potentiometer about the VS position gives indication of the edges of the deadband by illumination of either the ‘volts high’ or the ‘volts low’ LED’s. With ∆V% set at 3% there should be an obvious deadband as the ‘test volts’ potentiometer is moved above and below VS setting. 5.2.3 Initial time delay Set selection switch to ‘definite’. Set the voltage within the deadband by adjusting the ‘test volts’ potentiometer. Set initial delay to desired value. Adjust ‘test volts’ potentiometer to bring the voltage outside the deadband and start the stopwatch as the ‘volts high’ (or ‘volts low’) LED comes on; stop timing when the ‘tap’ LED comes on. The indicated time should be approximately equal to the initial delay setting. Note: 5.2.4 The initial delay timer is an integrating type and so it resets at a rate equal to the rate at which it times out. The timer can be reset instantaneously if the voltage is swung through the deadband from one side to the other and returned immediately to inside the deadband. Following this procedure before a timing check will ensure that the timer is starting from zero time. The initial delay timer resets where the voltage varies about the centre of the deadband, i.e. the actual VS setting. Intertap time delay If the test voltage is left outside the deadband after the initial time delay has elapsed then a check may be made on the ‘intertap’ time delay. With the intertap time set for 10 seconds there will be a 10 second delay between successive tapping outputs. To measure this time approximately, start the stopwatch when the ‘tap’ LED goes out and stop the stopwatch when it comes on again. Reduction of the intertap time to below 0 seconds will result in a continuous output indicated by a continuously illuminated ‘tap’ LED. 5.2.5 Undervoltage detector VU Set VU to the desired value. Reduce the test volts until the VU LED just comes on; the indicated voltage should be approximately equal to the set voltage VU. 5.2.6 Overvoltage detector VO Set VO to the desired value. Increase the test volts until the VO LED just comes on; the indicated voltage should be approximately equal to the set voltage VO. 5.2.7 Fixed 80% undervoltage detector Set the initial delay fully anticlockwise (to give minimum time delay) Set the intertap time fully anticlockwise (to give continuous output) Set the test volts to between 80% and 100% of set VS, so that the relay times out. Gradually reduce the test volts until the ‘tap’ LED goes out; the indicated voltage should be approximately 80% of the set VS. 31 5.2.8 Alarm timer To test the timer ensure S9 is in position B. Reset the alarm timer by bringing the test volts inside the deadband. Adjust the test volts outside the deadband and start the stopwatch; stop the stopwatch when the ‘alarm’ LED comes on. The indicated time should be approximately 3 minutes. Section 6 6.1 PROBLEM ANALYSIS Servicing instructions In addition to the maintenance functional checks of the voltage operated circuits, the following instructions provide a complete functional and calibration check for relay type MVGC 01. Should any of the relay’s functions found to be faulty it is recommended that the complete relay is returned to the ALSTOM T&D Protection & Control factory or local service agency. Should the need arise for the equipment to be returned to ALSTOM T&D Protection & Control Ltd for repair, then the form at the back of this manual should be completed and sent with the equipment together with a copy of any commissioning test results. The following instructions are essentially laboratory bench tests requiring high accuracy instrumentation. 6.2 Equipment and input requirements: Auxiliary supply of rated VX voltage to supply a 30 VA load. Stable three phase measuring voltage supply to operate between 70V and 170V ac into a 3VA load at rated frequency. Load current and circulating current inputs require stable current sources from 0 to 10A ac, burden 10VA. Phase shifter to adjust relative phase angle, so that the voltage may lead the current by phase angles of 0°, 90° and 180°. Phase angle meter, typical accuracy ±2°. High accuracy TRMS ac voltmeter, ac voltage accuracy less than 0.1% at full range 50 or 60 Hz. Note: 6.3 Test procedure Note: 6.3.1 The measuring voltage supply will require a fine adjustment control accurately to determine the edge of deadband limits. The accuracy limits specified in the following tests make no allowance for instrument error. Regulated voltage setting VS Set VS to 100 V, ∆V% to 1% and the TEST/NORMAL switch to NORMAL. Apply 100V to relay terminals 17 and 18 and slowly increase this voltage until the VOLTS HIGH’ LED just illuminates. Measure the input voltage using a high accuracy voltmeter connected to the VOLTAGE MONITOR sockets on the front of the relay and note the VOLTS HIGH value, VH. Reduce the input voltage until the VOLTS LOW LED just comes on; note this voltage, VL. 32 Actual voltage setting VS = actual VS = set VS ±0.5% Tolerance: 6.3.2 VH + VL volts 2 Deadband setting ∆V% Set desired ∆V% value and again measure VOLTS HIGH and VOLTS LOW values. VH – VL x 100% (for all values of VS) 2 VH – VL % (for VS set at 100V) 2VS or ± ∆V% = 6.3.3 Initial delay To measure accurately the initial delay it is necessary to connect a variable resistor in series with the measuring voltage supply to relay terminals 17 and 18 as shown in Figure 7. Timer stop Timer start S1 1 5 3 17 MVGC VS R VN Stable voltage supply 18 Figure 7 Potentiometer R should be approximately 5kΩ, 2W. The input voltage VS on terminals 17 and 18 is monitored at the ‘VOLTAGE MONITOR’ sockets with the ‘TEST’ switch in ‘NORMAL’ position. Set initial time delay multiplier to 10. a) Definite times To check times on the lower side of the deadband: set VN equal to the thumbwheel setting, open switch S1 and adjust R to reduce the monitored voltage to the required value below set VS. Close S1 so that VS returns inside the deadband and allow time for the relay to reset. Opening S1 will now initiate a time delay which can be measured on the timer. Required timer accuracy: accurate to 0.1 second Initial delay accuracy: ±5% of INITIAL setting To check ‘volts high’ times: set VN to required value above set VS. Open S1 and adjust R to bring VS into the deadband. Arrange the timer to start on opening of S1 and open S1 to measure time delay. Accuracy: ±5% of INITIAL setting Note: The initial timer can be reset instantaneously by a varying input voltage both above and below the VS setting or alternatively by removing input volts. This operates the 80% undervoltage circuits. 33 b) Inverse times Select the inverse characteristic and set initial delay to 120 seconds. Check the time delay for voltage deviation of 5 times and 10 times the deadband setting away from the VS setting. Voltage deviation (N) Time delay 5x 10x 6.3.4 24s 12s Tolerance ±15% Intertap delay Set the initial delay to 15 seconds and apply voltage to the relay to cause a volts low or volts high condition. When the initial delay has elapsed the output relay will continue to give pulsed closure for 1 second at intervals determined by the intertap delay setting. Arrange for the timer to start when the output contacts open and stop when they reclose. The measured time is the intertap delay. Tolerance: ±5% of setting 6.3.5 Fixed 80% undervoltage blocking Set VS = 100V, initial delay = 15s inverse and intertap delay to continuous. i.e. less than zero. With 82V applied the relay should time out and give a continuous output and the ‘TAP’ LED should go out above 79V. 6.3.6 Line drop compensation For these circuits to work correctly it is important to observe correct polarities for voltage and current connections. See Figure 8. Volts Current Phase shifter 17 25 A MVGC V 18 26 Figure 8 Set VS = 100 V ∆V% = ±1 a) Resistive compensation scale VR With rated current applied to relay terminals 27 and 28 adjust the phase shift such that the voltage leads the current by 90°. Set : VC = VXL = 0, VR = 24 and VR multiplier = 1. 34 Obtain the new deadband centre voltage by recording the voltages at which the ‘volts low’ and ‘volts high’ LED’s illuminate. Deadband centre = VH + VL volts 2 This should be an increase of 24V ±5% on the actual VS value obtained in Section 6.3.1. b) Reactive compensation scale VXL Set : VC = VR = 0, VXL = 24V ‘direct’ and VXL multiplier =1. Apply rated current in antiphase with VS and obtain the deadband centre voltage as before. Again deadband centre = actual VS + 24V Tolerance = ±5% of 24V Adjust phase shift to give current and voltage in phase and with VXL = 24V ‘REVERSE’, check that deadband centre is within ±2% of the value determined for current and voltage in antiphase. i.e. VS – (–24V) = VS + 24V. 6.3.7 Parallel compensating voltage, VC The relay is connected as shown in Figure 9. Ensure that pilot wire connection terminals 23 and 24 are open circuited. Apply rated current, to be in phase with the measuring voltage supply, to terminals 25 and 26. Set VC = 24 and obtain the new deadband centre by recording the voltages at which the ‘volts high’ and ‘volts low’ LED’s just come on. This should be actual VS + 24V Tolerance = ±5% of 24V By short circuiting the pilot terminals 23 and 24 the deadband centre should be returned to the actual VS value independent of the VC setting or applied current. 6.3.8 Load shedding/voltage boost The effective regulated voltage setting can be altered by selected amounts as indicated by the load shedding LED indications. Connect terminal 22 to terminals 19, 20 and 21 to give load shedding as follows: Link Actual VS value is altered by: 19 and 22 –3% or +3% 20 and 22 –6% or +1.5% 21 and 22 –9% or –1.5% Check the appropriate LED indicator operates. Remove the link after test. 6.3.9 Supervision circuits (i) Undervoltage and overvoltage relays operate where the input voltage is below or above VU and VO settings respectively. 35 Set VS = 115V, ∆V% = ±0.5% With VO = 110V and VU = 80V adjust the input voltage to just operate the overvoltage relay, but below the lower deadband limit at approximately 113V. Check that operation of the raise contact, terminals 1 and 3, is blocked by operation of the overvoltage relay. Set VO = 140V and check that raise output is no longer blocked. Similarly, with VO = 140V and VU = 120V, set the input volts just above the upper deadband limit at about 117V with the undervoltage relay operated. Check that operation of the lower contact, terminals 3 and 5, is blocked by operation of the undervoltage relay. (ii) The overcurrent blocking relay operates where the total load current exceeds the IL setting. Set IL = 150% IN, IN = rated current Apply 150% IN current to load current CT input, terminals 27 and 28. Check that operation of overcurrent detector blocks both raise and lower output contacts. (iii) The alarm output relay operates where the input voltage remains continuously outside the set deadband limits. If S9 is fitted then it must be set to position B for this test. Connect the relay as in Figure 7, but connect stop terminals of timer to output contacts of the alarm relay, terminals 6 and 8 or 10 and 12. With SWl open adjust R such that the input voltage is within the set deadband. Operation of SWl causes the relay to go to a volts high condition. Check that the alarm LED and output relay operate after a period of approximately 180 seconds. (iv) The circulating current detector operates where the circulating current between transformers connected in parallel, exceeds the IC setting. Apply a current source to terminals 25 and 26 with terminals 23 and 24 open circuited. Set IC = 25% IN and set internal switches SW7 and SW8 to position A (see Section 2.11). Apply 25% of rated current and check that LED indication is given for excessive circulating current. Set VC = 0 With the excessive circulating current detector operated, check that raise and lower outputs are given. Check with SW7 in position B, that raise and lower outputs are blocked by operation of a common blocking relay. Operation of the circulating current detector initiates the alarm output relay. If S10 is fitted then it must be selected to position A for this test. Adjust the relay input volts to be within the set deadband. Check that the alarm output relay operates 180 seconds after the operation of the circulating current detector. Check with SW8 in position B, that the alarm output relay operates instantaneously with the operation of the circulating current detector. 36 6.4 Re-calibration If necessary relay type MVGC 01 may be re-calibrated using the trimming potentiometers indicated in the following table: Scale Calibration adjustment Adjustment of highest setting Adjustment of lower setting VS – RV3 RV2 ∆V% – RV5 RV6 Initial delay – RV9 RV8 Intertap delay – RV11 – 80% U/V inhibit RV12 – – VU – RV23 RV24 VO – RV20 RV21 IL – RV29 RV30 IC – RV26 RV27 Alarm Timer RV31 – – VR – RV16 RV34 VXL – RV14 RV33 VC – RV18 RV32 Each setting can be calibrated to be within the specified tolerance. It is essential that high accuracy instrumentation is used throughout calibration. Adjustment of RV2 can be used to provide a fine adjustment to give interim values of VS setting. 37 38 220V 28 27 23 24 26 13 21 20 19 22 18 17 Figure 9 RL7–2 RL7–1 Power supply circuits VXL x1 x1 Range VR IL VC x1 x1 Range IC Loadshedding RL5 2 In ∑ B A S6 1 VS VS S10 VU VO 1 B F(A>B) VS <80%VS Inverse Define A < VU RL4 4 > VO RL3 2 1 Volts High Low RL3 RL4 RL6 Test 1 9 7 4 2 8 6 1 E E R t x1 x1 Range S8 S9 Over voltage Under voltage Alarm RL7 2 A B B A Note: Both ranges of load shedding limits are shown. The relay will have limits of either –3%, –6%, –9% or +3%, +1.5%, –1.5% as specified with order. –3% –6% –9% Com +3% +1.5% –1.5% Out Direct Reverse >IL >IC S7 A B Application diagram: Static voltage regulating relay Auxiliary 110V 15 volts 14 0V Ref. volts CT Pilot CT 25 RL1 RL2 & & & 1 RL3 RL5 RL4 RL6 1 1 1 3 5 12 10 1s R Raise volts Common Lower volts Alarm t 0–10s 1 & & t 3 min Tap Raise Lower RL1 2 RL2 2 Alarm RL6 2 Section 7 COMMISSIONING TEST RECORD TYPE MVGC STATIC VOLTAGE REGULATING CONTROL RELAY DATE .................................... STATION CIRCUIT RELAY MODEL NO. MVGC SERIAL NO. RATED AC VOLTAGE VN RATED AC AUXILIARY VOLTAGE VX SET ON RELAY RATED AC CURRENT IN SET ON RELAY FREQUENCY Hz 4.2.3 VOLTAGE SETTlNG (VS) EXPECTED VOLTAGE SETTING (VS) V ‘VOLTS HlGH’ THRESHOLD (VH) V ‘VOLTS LOW’ THRESHOLD (VL) V ACTUAL VOLTAGE SETTING % ERROR = 100 4.2.4 ( V 2V+ V –1) H (VH + VL) 2 V L V S PERCENTAGE DEVIATION (∆V%) EXPECTED PERCENTAGE DEVIATION (∆V%) ACTUAL PERCENTAGE DEVIATION = 100 4.2.5 % ( V 2V– V ) H L S % UNDER VOLTAGE BLOCKING (80% VS) EXPECTED UNDER VOLTAGE BLOCKING (80% VS) V ACTUAL UNDERVOLTAGE BLOCKING V 39 4.2.6 LOAD SHEDDING VOLTAGES EXPECTED LOAD SHEDDING VOLTAGES –3% V –6% V –9% V or +3% V +1.5% V –1.5% V V +1.5% V –1.5% V ACTUAL LOAD SHEDDING VOLTAGES –3% 4.2.7 V –6% V –9% V or +3% INITIAL TlME DELAY EXPECTED INITIAL TIME DELAY (DEFINITE) Secs ACTUAL INITIAL TIME DELAY (DEFINITE) Secs EXPECTED INITIAL TIME DELAY (INVERSE) Secs ACTUAL INITIAL TIME DELAY (INVERSE) Secs INTERTAP TIME DELAY 4.2.8 EXPECTED INTERTAP TlME DELAY Secs ACTUAL INTERTAP TIME DELAY Secs LINE DROP COMPENSATION VOLTAGE (VR & VXL) EXPECTED RESISTIVE COMP. VOLTS (VR) V ‘VOLTS HIGH’ THRESHOLD (VH.R) V ‘VOLTS LOW’ THRESHOLD (VL.R) V ACTUAL VOLTAGE SETTING (VH.R + VL.R) 2 V ACTUAL RESISTIVE COMP VOLTS (VH.R + VL.R) 2 (VH + VL) 2 – V EXPECTED REACTIVE COMP. VOLTS (VXL) V ‘VOLTS HIGH’ THRESHOLD (VH.XL) V ‘VOLTS LOW’ THRESHOLD (VL.XL) V ACTUAL VOLTAGE SETTING (VH.XL + VL.XL) 2 V ACTUAL REACTIVE COMP. VOLTS (VH.XL + VL.XL) 2 – (VH + VL) 2 V 40 4.2.9 PARALLEL COMPENSATION VOLTAGE (VC) EXPECTED PARALLEL COMP. VOLTS (VC) V ‘VOLTS HIGH’ THRESHOLD (VH.C) V ‘VOLTS LOW’ THRESHOLD (VL.C) V ACTUAL VOLTAGE SETTlNG (VH.C + VL.C) 2 V ACTUAL PARALLEL COMP. VOLTS (VH.C + VL.C) 2 – (VH* + VL*) 2 V * VH and VL as in 4.2.3. 4.2.10 SUPERVISION (i) UNDER VOLTAGE DETECTION (VU) EXPECTED UNDER VOLTAGE SETTING VU V ACTUAL UNDER VOLTAGE SETTING V OVERVOLTAGE DETECTION (VO) EXPECTED OVER VOLTAGE SETTING VO V ACTUAL OVER VOLTAGE SETTING V (ii) OVER CURRENT DETECTION (IL) EXPECTED OVERCURRENT SETTING (IL) A ACTUAL OVERCURRENT SETTING A (iii) CIRCULATING CURRENT DETECTOR (IC) EXPECTED OVERCURRENT SETTING (IC) A ACTUAL OVERCURRENT SETTING A (iv) ALARM: AFTER 3 MINUTES s 41 4.2.11 LOAD CHECK VOLTS AT RECEIVING END (VR) V VOLTS LOW LAMP WHEN VS IS SET AT V VOLTS HIGH LAMP WHEN VS IS SET AT V AVERAGE VS (SHOULD BE = VR APPROX.) V _____________________________________ ______________________________________ Commissioning Engineer Customer Witness _____________________________________ ______________________________________ Date Date 42 REPAIR FORM Please complete this form and return it to ALSTOM T&D Protection & Control Ltd with the equipment to be repaired. This form may also be used in the case of application queries. ALSTOM T&D Protection & Control Ltd St. Leonards Works Stafford ST17 4LX, England For: After Sales Service Department Customer Ref: ___________________________ Model No: __________________ Contract Ref: ___________________________ Serial No: Date: ___________________________ 1. __________________ What parameters were in use at the time the fault occurred? AC volts _____________ Main VT/Test set DC volts _____________ Battery/Power supply AC current _____________ Main CT/Test set Frequency _____________ 2. Which type of test was being used? ____________________________________________ 3. Were all the external components fitted where required? (Delete as appropriate.) 4. List the relay settings being used Yes/No ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ 5. What did you expect to happen? ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ continued overleaf ✁ 43 6. What did happen? ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ 7. 8. When did the fault occur? Instant Yes/No Intermittent Yes/No Time delayed Yes/No (Delete as appropriate). By how long? ___________ What indications if any did the relay show? ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ 9. Was there any visual damage? ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ 10. Any other remarks which may be useful: ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ ______________________________________ Signature _______________________________________ Title ______________________________________ Name (in capitals) _______________________________________ Company name ✁ 44 45 Publication: R8021G AREVA T&D's Automation & Information Systems Business www.areva-td.com T&D Worldwide Contact Centre online 24 hours a day: +44 (0) 1785 25 00 70 http://www.areva-td.com/contactcentre/
