21-Relay Testing and Commissioning

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Chap21-370-397

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21.1 INTRODUCTION

The testing of protection equipment schemes presents a The testing of protection equipment schemes presents a number of

number of problems. problems. This is because This is because the main functionthe main function of protection equipment is solely concerned with of protection equipment is solely concerned with operation under system fault conditions, and cannot operation under system fault conditions, and cannot readily be tested under normal system operating readily be tested under normal system operating conditions.

conditions. This This situation situation is is aggravated aggravated by by thethe increasing complexity of protection schemes and use of increasing complexity of protection schemes and use of relays containing software.

relays containing software.

The testing of protection equipment may be divided into The testing of protection equipment may be divided into four stages:

four stages: i.

i. type teststype tests ii.

ii. routine factory production testsroutine factory production tests iii.

iii. commissioning testscommissioning tests iv.

iv. periodic maintenance testsperiodic maintenance tests

21.1.1 Type Tests

Type tests are required to prove that a relay meets the Type tests are required to prove that a relay meets the published specification and complies with all relevant published specification and complies with all relevant standards.

standards. Since the Since the principal function of principal function of a protectiona protection relay is to operate correctly under abnormal power relay is to operate correctly under abnormal power conditions, it is essential that the performance be conditions, it is essential that the performance be assessed

assessed under under such such conditions. conditions. Comprehensive Comprehensive typetype tests simulating the operational conditions a

tests simulating the operational conditions a re thereforere therefore conducted at the manufacturer's works during the conducted at the manufacturer's works during the development and certification of the equipment.

development and certification of the equipment.

The standards that cover most aspects of relay The standards that cover most aspects of relay performance are IEC

performance are IEC 60255 and ANSI 60255 and ANSI C37.90. C37.90. HoweverHowever compliance may also involve consideration of the compliance may also involve consideration of the requirements of IEC 61000, 60068 and 60529, while requirements of IEC 61000, 60068 and 60529, while products intended for use in the EEC also have to c products intended for use in the EEC also have to c omplyomply with the requirements of Directives 89/336/EEC and with the requirements of Directives 89/336/EEC and 73/23/EEC.

73/23/EEC. Since type testing Since type testing of a of a digital or digital or numericalnumerical relay involves testing of software as well as hardware, relay involves testing of software as well as hardware, the type testing process is very complicated and more the type testing process is very complicated and more involved than a static or electromechanical relay. involved than a static or electromechanical relay.

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Relay Testing

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Chap21-370-397

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21.1.2 Routine Factory Production Tests

These are conducted to prove that relays are free from These are conducted to prove that relays are free from defects during

defects during manufacture. manufacture. Testing will Testing will take place take place atat several stages during manufacture, to ensure problems several stages during manufacture, to ensure problems are discovered at the earliest possible time and hence are discovered at the earliest possible time and hence minimise remedial

minimise remedial work. work. The extent The extent of testing of testing will bewill be determined by the complexity of the relay and past determined by the complexity of the relay and past manufacturing experience.

manufacturing experience.

21.1.3 Commissioning Tests

These tests are designed to prove that a particular These tests are designed to prove that a particular protection scheme has been installed correctly prior to protection scheme has been installed correctly prior to setting to

setting to work. work. All aspects All aspects of of the the scheme arescheme are thoroughly checked, from installation of the correct thoroughly checked, from installation of the correct equipment through wiring checks and operation checks equipment through wiring checks and operation checks of the individual items of equipment, finishing with of the individual items of equipment, finishing with testing of the complete scheme.

testing of the complete scheme.

21.1.4 Periodic Maintenance Checks

These are required to identify equipment failures and These are required to identify equipment failures and degradation in service, so that corrective action can be degradation in service, so that corrective action can be taken.

taken. Because a protection scheme Because a protection scheme only operates underonly operates under fault conditions, defects may not be revealed for a fault conditions, defects may not be revealed for a significant period o

significant period of time, f time, until a fault until a fault occurs. occurs. RegularRegular testing assists in detecting faults that would otherwise testing assists in detecting faults that would otherwise remain undetected until a fault occurs.

remain undetected until a fault occurs.

21.2 ELECTRICAL TYPE TESTS

Various electrical type tests must be performed, as Various electrical type tests must be performed, as

follows: follows:

21.2.1 Functional Tests

The functional tests consist of applying the appropriate The functional tests consist of applying the appropriate inputs to the relay under test and measuring the inputs to the relay under test and measuring the performance to determine if it meets the specification. performance to determine if it meets the specification. They are usually carried out under controlled They are usually carried out under controlled environmental conditions.

environmental conditions. The testing The testing may be may be extensive,extensive, even where only a simple relay function is being tested., even where only a simple relay function is being tested., as can be realised by considering the simple overcurrent as can be realised by considering the simple overcurrent relay element of Table 21.1.

relay element of Table 21.1.

To determine compliance with the specification, the tests To determine compliance with the specification, the tests listed in Table 2

listed in Table 21.2 are required to 1.2 are required to be carried out. be carried out. This isThis is a time consuming task, involving many engineers and a time consuming task, involving many engineers and technicians.

technicians. Hence Hence it is it is expensive.expensive.

When a modern numerical relay with many functions is When a modern numerical relay with many functions is considered, each of which has to be type-tested, the considered, each of which has to be type-tested, the functional type-testing involved is

functional type-testing involved is a major issue. a major issue. In theIn the case of a recent relay development project, it was case of a recent relay development project, it was calculated that if one person had to do all the work, it calculated that if one person had to do all the work, it

would take 4 years to write the functional type-test would take 4 years to write the functional type-test specifications, 30 years to perform the tests and several specifications, 30 years to perform the tests and several years to

years to write the write the test reports test reports that result. that result. AutomatedAutomated techniques/ equipment are clearly required, and are techniques/ equipment are clearly required, and are covered in Section 21.7.2. covered in Section 21.7.2. • • 2121•• R R e e l l a a y y T T e e s s t t i i n n g g a a n n d d C C o o m m m m i i s s s s i

i o o

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EElleemmeenntt RRaannggee SStteep p SSiizzee

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Direrectctioionanalilityty FoForwrwarard/d/ReReveversrse/e/NoNon-n-didirerectctioionanall R

RCCAA --9955°° ttoo++9955°° 11°° C

Chhaarraacctteerriissttiicc DDTT//IIDDMMTT D

Deeffiinniitte e TTiimme e DDeellaayy 0 0 - - 110000ss 00..0011ss IEC IDMT Time Delay

IEC IDMT Time Delay

IEC Standard Inverse IEC Standard Inverse IEC Very Inverse IEC Very Inverse IEC Extremely Inverse IEC Extremely Inverse UK Long Time Inverse UK Long Time Inverse

TTiimme e MMuullttiipplliieer r SSeettttiinng g ((TTMMSS)) 00..00225 5 - - 11..22 00..002255 IEEE Moderately Inverse

IEEE Moderately Inverse IEEE Very Inverse IEEE Very Inverse IIEEEEE E IIDDMMT T TTiimme e DDeellaayy IIEEEEE E EExxttrreemmeelly y IInnvveerrssee

US-CO8 Inverse US-CO8 Inverse US-CO2 Short Time Inverse US-CO2 Short Time Inverse

TTiimme e DDiiaal l ((TTDD)) 00..5 5 - - 1155 00..11 IIEEC C RReesseet t TTiimme e ((DDT T oonnllyy)) 0 0 - - 110000ss 00..0011ss

IIEEEEE E RReesseet t TTiimmee IIDDMMTT//DDTT

IIEEEEE E DDT T RReesseet t TTiimmee 0 0 - - 110000ss 00..0011ss IEEE Moderately Inverse

IEEE Moderately Inverse IEEE Very Inverse IEEE Very Inverse IIEEEEE E IIDDMMT T RReesseet t TTiimmee IIEEEEE E EExxttrreemmeelly y IInnvveerrssee

US-C

US-CO8O8 InveInverserse US-CO2 Short Time Inverse US-CO2 Short Time Inverse

Table 21.1:

Table 21.1: Overcurrent relay element specificatOvercurrent relay element specificationion

Table 21.2:

Table 21.2: Overcurrent relay element functOvercurrent relay element functional type tests ional type tests

Test 1 Test 1 Test 2 Test 2 Test 3 Test 3 Test 4 Test 4 Test 5 Test 5 Test 6 Test 6 Test 7 Test 7 Test 8 Test 8 Test 9 Test 9 Test 10 Test 10 Test 11 Test 11 Test 12 Test 12 Test 13 Test 13 Test 14 Test 14

Three phase non-directional pick up and drop off accuracy Three phase non-directional pick up and drop off accuracy

over complete current setting range for both stages over complete current setting range for both stages Three phase directional pick up and drop off accuracy Three phase directional pick up and drop off accuracy over complete RCA setting range in the forward direction, over complete RCA setting range in the forward direction,

current angle sweep current angle sweep

Three phase directional pick up and drop off accuracy Three phase directional pick up and drop off accuracy over complete RCA setting range in the reverse direction, over complete RCA setting range in the reverse direction,

current angle sweep current angle sweep

Three phase directional pick up and drop off accuracy Three phase directional pick up and drop off accuracy over complete RCA setting range in the forward direction, over complete RCA setting range in the forward direction,

voltage angle sweep voltage angle sweep

Three phase directional pick up and drop off accuracy Three phase directional pick up and drop off accuracy over complete RCA setting range in the reverse direction, over complete RCA setting range in the reverse direction,

voltage angle sweep voltage angle sweep

Three phase polarising voltage threshold test Three phase polarising voltage threshold test Accuracy of DT timer over complete setting range Accuracy of DT timer over complete setting range Accuracy of IDMT curves over claimed accuracy range Accuracy of IDMT curves over claimed accuracy range

Accuracy of IDMT TMS/TD Accuracy of IDMT TMS/TD

Effect of changing fault current on IDMT operating times Effect of changing fault current on IDMT operating times Minimum Pick-Up of Starts and Trips for IDMT curves Minimum Pick-Up of Starts and Trips for IDMT curves

Accuracy of reset timers Accuracy of reset timers

Effect of any blocking signals, opto inputs, VTS, Autoreclose Effect of any blocking signals, opto inputs, VTS, Autoreclose

Voltage polarisation memory Voltage polarisation memory

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21.2.2 Rating Tests

Rating type tests are conducted to ensure that Rating type tests are conducted to ensure that components are used within their specified ratings and components are used within their specified ratings and that there are no fire or electric shock hazards under a that there are no fire or electric shock hazards under a normal load or

normal load or fault condition of the power fault condition of the power system. system. ThisThis is in addition to checking that the product complies with is in addition to checking that the product complies with its technical

its technical specification. specification. The The following are following are amongstamongst the rating type tests conducted on protection relays, the the rating type tests conducted on protection relays, the specified parameters are normally to IEC 60255-6. specified parameters are normally to IEC 60255-6.

21.2.3 Thermal Withstand

The thermal withstand of VT’s, CT’s and output contact The thermal withstand of VT’s, CT’s and output contact circuits is determined to ensure compliance with the circuits is determined to ensure compliance with the specified continuous and short-term overload conditions. specified continuous and short-term overload conditions. In addition to functional verification, the pass criterion is In addition to functional verification, the pass criterion is that there is no detrimental effect on the relay assembly, that there is no detrimental effect on the relay assembly, or circuit components, when the product is subjected to or circuit components, when the product is subjected to overload conditions that may be expected in service. overload conditions that may be expected in service. Thermal withstand is assessed over a time period of 1s Thermal withstand is assessed over a time period of 1s for CT’s and 10s for VT’s.

for CT’s and 10s for VT’s.

21.2.4 Relay Burden

The burdens of the auxiliary supply, optically isolated The burdens of the auxiliary supply, optically isolated inputs, VT’s and CT’s are measured to check that the inputs, VT’s and CT’s are measured to check that the product complies

product complies with its specification. with its specification. The burden The burden of of products with a high number of input/output circuits is products with a high number of input/output circuits is application specific i.e. it increases according to the application specific i.e. it increases according to the number of optically isolated input and output contact number of optically isolated input and output contact ports which are energised under normal power system ports which are energised under normal power system load conditions.

load conditions. It is It is usually envisaged usually envisaged that not that not moremore than 50% of such ports will be energised in any than 50% of such ports will be energised in any application.

application.

21.2.5 Relay Inputs

Relay inputs are

Relay inputs are tested over the tested over the specified ranges. specified ranges. InputsInputs include those for auxiliary voltage, VT, CT, frequency, include those for auxiliary voltage, VT, CT, frequency, optically isolated digital inputs and communication optically isolated digital inputs and communication circuits.

circuits.

21.2.6 Relay Output Contacts

Protection relay output contacts are type tested to Protection relay output contacts are type tested to ensure that they comply with the product specification. ensure that they comply with the product specification. Particular withstand and endurance type tests have to be Particular withstand and endurance type tests have to be carried out using d.c., since the normal supply is via a carried out using d.c., since the normal supply is via a station battery.

station battery.

21.2.7 Insulation Resistance

The insulation resistance test is carried out according to The insulation resistance test is carried out according to IEC 60255-5, i.e. 500V d.c. ±10%, for a minimum of 5 IEC 60255-5, i.e. 500V d.c. ±10%, for a minimum of 5

seconds.

seconds. This is carried out This is carried out between all circuits and casebetween all circuits and case earth, between all independent circuits and across earth, between all independent circuits and across normally open

normally open contacts. contacts. The acceptance The acceptance criterion for criterion for aa product in new condition is a

product in new condition is a minimum of 100Mminimum of 100MΩΩ_{. After}_{. After}

a damp heat test the pass criterion is a minimum of a damp heat test the pass criterion is a minimum of 10M

10MΩΩ_..

21.2.7 Auxiliary Supplies

Digital and numerical protection relays normally require Digital and numerical protection relays normally require an auxiliary supply to provide power to the on-board an auxiliary supply to provide power to the on-board microprocessor circuitry and the interfacing microprocessor circuitry and the interfacing opto-isolated input

isolated input circuits and circuits and output relays. output relays. The auxiliaryThe auxiliary supply can be either a.c. or d.c., supplied from a number supply can be either a.c. or d.c., supplied from a number of sources or safe supplies - i.e. batteries, UPS’, of sources or safe supplies - i.e. batteries, UPS’, generators, etc., all of which may be subject to voltage generators, etc., all of which may be subject to voltage dips,

dips, short interruptions short interruptions and voltage and voltage variations. variations. RelaysRelays are designed to ensure that operation is maintained and are designed to ensure that operation is maintained and no damage occurs during a disturbance of the auxiliary no damage occurs during a disturbance of the auxiliary supply.

supply.

Tests are carried out for both a.c. and d.c. auxiliary Tests are carried out for both a.c. and d.c. auxiliary supplies and include mains variation both above and supplies and include mains variation both above and below the nominal rating, supply interruptions derived by below the nominal rating, supply interruptions derived by open circuit and short circuit, supply dips as a open circuit and short circuit, supply dips as a percentage of

percentage of the nominal the nominal supply, supply, repetitive starts. repetitive starts. TheThe duration of the interruptions and supply dips range from duration of the interruptions and supply dips range from 2ms to 60s

2ms to 60s intervals. intervals. A short supply A short supply interruption or dipinterruption or dip up to 20ms, possibly longer, should not cause any up to 20ms, possibly longer, should not cause any malfunction

malfunction of of the the relay. relay. Malfunctions Malfunctions include include thethe operation of output relays and watchdog contacts, the operation of output relays and watchdog contacts, the reset of microprocessors, alarm or trip indication, reset of microprocessors, alarm or trip indication, acceptance of corrupted data over the communication acceptance of corrupted data over the communication link and the corruption of

link and the corruption of stored data or settings. stored data or settings. For aFor a longer supply interruption, or dip in excess of 20ms, the longer supply interruption, or dip in excess of 20ms, the relay self recovers without the loss of any function, data, relay self recovers without the loss of any function, data, settings or

settings or corruption of corruption of data. data. No operator No operator interventionintervention is required to restore operation after an interruption or is required to restore operation after an interruption or dip in the

dip in the supply. supply. Many relays have a Many relays have a specification thatspecification that exceeds this requirement, tolerating dips of up to 50ms exceeds this requirement, tolerating dips of up to 50ms without operation being affected.

without operation being affected.

In addition to the above, the relay is subjected to a number In addition to the above, the relay is subjected to a number of repetitive starts or a sequence of supply interruptions. of repetitive starts or a sequence of supply interruptions. Again the relay is tested to ensure that no damage or data Again the relay is tested to ensure that no damage or data corruption has occurred during the repetitive tests. corruption has occurred during the repetitive tests. Specific tests carried out on d.c. auxiliary supplies Specific tests carried out on d.c. auxiliary supplies include reverse polarity, a.c. waveform superimposed on include reverse polarity, a.c. waveform superimposed on the d.c. supply and the effect of a rising and decaying the d.c. supply and the effect of a rising and decaying auxiliary voltage.

auxiliary voltage. All tests All tests are carried are carried out at out at variousvarious levels of loading of the relay auxiliary supply.

levels of loading of the relay auxiliary supply.

21.3 ELECTROMAGNETIC COMPATIBILITY TESTS

There are numerous tests that are carried out to There are numerous tests that are carried out to determine the ability of relays to withstand the electri determine the ability of relays to withstand the electri calcal

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environment in

environment in which they are which they are installed. installed. The substationThe substation environment is a very severe environment in

environment is a very severe environment in terms of theterms of the electrical and electromagnetic interference that can electrical and electromagnetic interference that can arise.

arise. There are There are many sources omany sources of interference within f interference within aa substation, some originating internally, others being substation, some originating internally, others being conducted along the overhead lines or cables into the conducted along the overhead lines or cables into the substation

substation from from external external disturbancesdisturbances . . The The mostmost common sources are:

common sources are: a.

a. switching operationsswitching operations b.

b. system faultssystem faults c.

c. lightning strikeslightning strikes d.

d. conductor flashoverconductor flashover e.

e. telecommunication operations e.g. mobile phonestelecommunication operations e.g. mobile phones A whole suite of tests are performed to simulate these A whole suite of tests are performed to simulate these types of interference, and they fall under the broad types of interference, and they fall under the broad umbrella of what is known as EMC, or Electromagnetic umbrella of what is known as EMC, or Electromagnetic Compatibility tests.

Compatibility tests.

Broadly speaking, EMC can be defined as: Broadly speaking, EMC can be defined as:

‘The ability of equipment to co-exist in the same ‘The ability of equipment to co-exist in the same electromagnetic environment’

electromagnetic environment’

It is not a new subject and has been tested for by the It is not a new subject and has been tested for by the military ever since the advent of electro

military ever since the advent of electronic equipment. nic equipment. EMCEMC can cause real and serious problems, and does need to be can cause real and serious problems, and does need to be taken into account

taken into account when designing electronic equipment.when designing electronic equipment. EMC tests determine the impact on the relay under test EMC tests determine the impact on the relay under test of high-frequency electrical disturbances of various of high-frequency electrical disturbances of various kinds.

kinds. Relays manufactured or Relays manufactured or intended for intended for use in theuse in the EEC have to comply with EEC Directive 89/336/EEC in EEC have to comply with EEC Directive 89/336/EEC in this respect.

this respect. To achieve this, To achieve this, in addition to dein addition to designing forsigning for statutory compliance to this Directive, the following statutory compliance to this Directive, the following range of tests are carried out:

range of tests are carried out: a.

a. d.c. interrupt testd.c. interrupt test b.

b. a.c. ripple on d.c. supply testa.c. ripple on d.c. supply test c.

c. d.c. ramp testd.c. ramp test d.

d. high frequency disturbance testhigh frequency disturbance test e.

e. fast transient testfast transient test f.

f. surge immunity testsurge immunity test g.

g. power frequency interference testpower frequency interference test h.

h. electrostatic discharge testelectrostatic discharge test i.

i. conducted and radiated emissions testsconducted and radiated emissions tests j.

j. conducted and radiated immunity testsconducted and radiated immunity tests k.

k. power frequency magnetic field testspower frequency magnetic field tests

21.3.1 D.C Interrupt Test

This is a test to determine the maximum length of time This is a test to determine the maximum length of time

that the relay can withstand an interruption in the that the relay can withstand an interruption in the auxiliary supply without de-energising, e.g. switching auxiliary supply without de-energising, e.g. switching off, and that when this time is exceeded and it does off, and that when this time is exceeded and it does transiently switch off, that no maloperation occurs. transiently switch off, that no maloperation occurs. It simulates the effect of a loose fuse in the battery It simulates the effect of a loose fuse in the battery circuit, or a short circuit in the common d.c. supply, circuit, or a short circuit in the common d.c. supply, interrupted by a fuse.

interrupted by a fuse. Another source of Another source of d.c. interruptiond.c. interruption is if there is a power system fault and the battery is is if there is a power system fault and the battery is supplying both the relay and the circuit breaker trip coils. supplying both the relay and the circuit breaker trip coils. When the battery energises the coils to initiate the When the battery energises the coils to initiate the circuit breaker trip, the voltage may fall below the circuit breaker trip, the voltage may fall below the required level for operation of the relay and hence a d.c. required level for operation of the relay and hence a d.c. interrupt occurs.

interrupt occurs. The test is specified The test is specified in IEC 60255-1in IEC 60255-111 and comprises a interruptions

and comprises a interruptions of 2, 5, 10, 20, 50, 100 andof 2, 5, 10, 20, 50, 100 and 200ms.

200ms. For interruptions For interruptions lasting up lasting up to and to and includingincluding 20ms, the relay must not de-energise of maloperate, 20ms, the relay must not de-energise of maloperate, while for longer interruptions it must not maloperate. while for longer interruptions it must not maloperate. The relay is powered from a battery supply, and both The relay is powered from a battery supply, and both short circuit and open circuit interruptions are carried short circuit and open circuit interruptions are carried out.

out. Each interruption Each interruption is applied is applied 10 10 times, and times, and forfor auxiliary power supplies with a large operating range, auxiliary power supplies with a large operating range, the tests are performed at minimum, maximum, and the tests are performed at minimum, maximum, and other voltages across this range, to ensure compliance other voltages across this range, to ensure compliance over the complete range.

over the complete range.

21.3.2 A.C. Ripple on D.C. Supply

This test (IEC 60255-11) determines that the relay is able This test (IEC 60255-11) determines that the relay is able to operate correctly with a superimposed a.c. voltage on to operate correctly with a superimposed a.c. voltage on the d.c. supply

the d.c. supply. . This is caused by This is caused by the station battery beingthe station battery being charged by the battery charger, and the relevant waveform charged by the battery charger, and the relevant waveform is shown in Figure 21.1.

is shown in Figure 21.1. It consists of a 12% peak-to-peakIt consists of a 12% peak-to-peak ripple superimposed on the d.c. supply voltage.

ripple superimposed on the d.c. supply voltage.

For auxiliary power supplies with a large operating range, For auxiliary power supplies with a large operating range, the tests are performed at minimum, maximum, and the tests are performed at minimum, maximum, and other voltages across this range, to ensure compliance other voltages across this range, to ensure compliance for the complete range.

for the complete range. The interference is applied usingThe interference is applied using a full wave rectifier network, connected in parallel with a full wave rectifier network, connected in parallel with the battery supply

the battery supply. . The relay mThe relay must continue to ust continue to operateoperate without malfunction during the test.

without malfunction during the test.

i o o

n n i i n n g g N e t w o r k P N e t w o r k P r o t e c t i o n & A ur o t e c t i o n & A u t o m a t i o n G u i d et o m a t i o n G u i d e • 3 • 3 77 44 •• 11 33 99 33 11 33 00 66 11 22 11 99 11 11 33 22 11 00 44 55 99 55 88 88 77 11 77 88 44 66 99 77 66 11 00 55 22 33 44 33 66 33 44 99 22 66 22 11 77 55 88 88 11 0.00 0.00 10.00 10.00 20.00 20.00 30.00 30.00 40.00 40.00 50.00 50.00 60.00 60.00 VV oo lltt aa gg ee ((VV )) Time (ms) Time (ms) Figure 21.1:

Figure 21.1: A.C. ripple superimposed A.C. ripple superimposed on d.c.on d.c.

supply test

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21.3.3 D.C. Ramp Down/Ramp Up

This test simulates a failed station battery charger, which This test simulates a failed station battery charger, which would result in the auxiliary voltage to the relay slowly would result in the auxiliary voltage to the relay slowly ramping down.

ramping down. The ramp The ramp up part simulates up part simulates the batterythe battery being recharged after

being recharged after discharging. discharging. The relay must The relay must powerpower up cleanly when the voltage is applied and not up cleanly when the voltage is applied and not maloperate.

maloperate.

There is no international standard for this test,

There is no international standard for this test, so individualso individual manufacturers can decide if they wish to conduct such a manufacturers can decide if they wish to conduct such a test and what the test specification shall be.

test and what the test specification shall be.

21.3.4 High Frequency Disturbance Test

The High Frequency Disturbance Test simulates high The High Frequency Disturbance Test simulates high voltage transients that result from power system faults voltage transients that result from power system faults and plant

and plant switching operations. switching operations. It consists It consists of a of a 1MHz1MHz decaying sinusoidal waveform, as shown in Figure 21.2. decaying sinusoidal waveform, as shown in Figure 21.2. The interference is applied across each independent The interference is applied across each independent circuit (differential mode) and between each circuit (differential mode) and between each independent circuit and earth (common mode) via an independent circuit and earth (common mode) via an external coupling and

external coupling and switching network. switching network. The product isThe product is energised in both normal (quiescent) and tripped modes energised in both normal (quiescent) and tripped modes for this test, and must not maloperate when the for this test, and must not maloperate when the interference is applied for a 2 second duration.

interference is applied for a 2 second duration.

21.3.5 Fast Transient Test

The Fast Transient Test simulates the HV interference The Fast Transient Test simulates the HV interference caused by disconnector operations in GIS substations or caused by disconnector operations in GIS substations or breakdown of the SF6 insulation between conductors breakdown of the SF6 insulation between conductors and the

and the earthed enclosure. earthed enclosure. This interference This interference can eithercan either be inductively coupled onto relay circuits or can be be inductively coupled onto relay circuits or can be directly introduced via the

directly introduced via the CT or VT CT or VT inputs. inputs. It consists of It consists of a series of 15ms duration bursts at 300ms intervals, each a series of 15ms duration bursts at 300ms intervals, each burst consisting of a train of 50ns wide pulses with very burst consisting of a train of 50ns wide pulses with very fast (5ns typical) rise times (Figure 21.3), with a peak fast (5ns typical) rise times (Figure 21.3), with a peak voltage magnitude of 4kV.

voltage magnitude of 4kV.

The product is energised in both normal (quiescent) and The product is energised in both normal (quiescent) and tripped modes

tripped modes for this test. for this test. It must not mIt must not maloperate whenaloperate when the interference is applied in common mode via the the interference is applied in common mode via the integral coupling network to each circuit in turn, for 60 integral coupling network to each circuit in turn, for 60 seconds.

seconds. Interference is Interference is coupled coupled onto comonto communicationsmunications circuits, if required, using an external capacitive coupling circuits, if required, using an external capacitive coupling clamp.

clamp.

21.3.6 Surge Immunity Test

The Surge Immunity Test simulates interference caused The Surge Immunity Test simulates interference caused by major power system disturbances such as capacitor by major power system disturbances such as capacitor bank switching and lightning strikes on overhead lines bank switching and lightning strikes on overhead lines within 5km of the

within 5km of the substation. substation. The test waveform has The test waveform has anan open circuit voltage of 4k

open circuit voltage of 4kV for common mode surges andV for common mode surges and 2kV for

2kV for differential mode differential mode surges. surges. The test The test waveshapewaveshape consists on open circuit of a 1.2/50ms rise/fall time and consists on open circuit of a 1.2/50ms rise/fall time and a short

a short circuit current circuit current of 8/20mof 8/20ms rise/fall s rise/fall time. time. TheThe generator is capable of providing a short circuit test generator is capable of providing a short circuit test current of up to 2kA, making this test potentially current of up to 2kA, making this test potentially destructive.

destructive. The surgeThe surges are s are applied sequentially applied sequentially underunder software control via dedicated coupling networks in both software control via dedicated coupling networks in both differential and common modes with the product differential and common modes with the product energised in

energised in its normal its normal (quiescent) state. (quiescent) state. The productThe product shall not maloperate during the test, shall still operate shall not maloperate during the test, shall still operate within specification after the test sequence and sha within specification after the test sequence and sha ll notll not incur any permanent damage.

incur any permanent damage.

21.3.7 Power Frequency Interference

This test simulates the type of interference that is caused This test simulates the type of interference that is caused when there is a power system fault and very high levels when there is a power system fault and very high levels of fault current flow in the primary conductors or the of fault current flow in the primary conductors or the earth grid.

earth grid. This causes 50 This causes 50 or 60Hz or 60Hz interference to interference to bebe induced onto control and communications circuits. induced onto control and communications circuits. There is no international standard for this test, but one There is no international standard for this test, but one used by some Utilities is:

used by some Utilities is: a.

a. 500V r.m.s., common mode500V r.m.s., common mode b.

b. 250V r.m.s., differential mode250V r.m.s., differential mode

i o o

n n i i n n g g N e t w o r k P r N e t w o r k P r o t e c t i o n & A u t oo t e c t i o n & A u t o m a t i o n G u i d em a t i o n G u i d e • 3• 3 77 55 •• R Reeppeettiittiioon n ppeerriioodd tt V V tt Burst duration (1/15 ms) Burst duration (1/15 ms) Burst period, 300 ms Burst period, 300 ms

5 ns rise time, 50 ns pulse width 5 ns rise time, 50 ns pulse width

Figure 21.3:

Figure 21.3: Fast Transient Test wavefFast Transient Test waveformorm

V V o o l l t t a a g g e e 00 Time Time Figure 21.2:

Figure 21.2: High Frequency DisturbaHigh Frequency Disturbance nce

Test waveform

Test waveform Chap21-370-397

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applied to circuits for which power system inputs

applied to circuits for which power system inputs are notare not connected.

connected.

Tests are carried out on each circuit, with the relay in the Tests are carried out on each circuit, with the relay in the following modes of operation:

following modes of operation: 1.

1. current and voltage applied at 90% of setting,current and voltage applied at 90% of setting, (relay not tripped)

(relay not tripped) 2.

2. current and voltage applied at 110% of setting,current and voltage applied at 110% of setting, (relay tripped)

(relay tripped) 3.

3. main protection and communications functionsmain protection and communications functions are tested to determine the effect of the are tested to determine the effect of the interference

interference

The relay shall not maloperate during the test, and shall still The relay shall not maloperate during the test, and shall still perform its main functions within the claimed tolerance. perform its main functions within the claimed tolerance.

21.3.8 Electrostatic Discharge Test

This test simulates the type of high voltage interference This test simulates the type of high voltage interference that occurs when an operator touches the relay

that occurs when an operator touches the relay’’s fronts front panel after being char

panel after being charged to a high potential. ged to a high potential. This is exactlyThis is exactly the same phenomenon as getting an electric shock when the same phenomenon as getting an electric shock when stepping out of a car or after walking on a synthetic fibre stepping out of a car or after walking on a synthetic fibre carpet.

carpet.

In this case the discharge is onl

In this case the discharge is only ever applied to the fronty ever applied to the front panel of the relay

panel of the relay, with the cover bo, with the cover both on and off. th on and off. TwoTwo types of discharges are applied, air discharge and contac types of discharges are applied, air discharge and contac tt discharge.

discharge. Air discharges are Air discharges are used on used on surfaces that aresurfaces that are normally insulators, and contact discharges are used on normally insulators, and contact discharges are used on surfaces that are

surfaces that are normally conducting. normally conducting. IEC 60255-22-2IEC 60255-22-2 is the relevant standard this test, for which the test is the relevant standard this test, for which the test parameters are:

parameters are: a.

a. cover on: Class 4, 8kV contact discharge, 15kV aircover on: Class 4, 8kV contact discharge, 15kV air discharge

discharge b.

b. cover off: Class 3, 6kV contact discharge, 8kV aircover off: Class 3, 6kV contact discharge, 8kV air discharge

discharge

In both cases above, all the lower test levels are also In both cases above, all the lower test levels are also tested.

tested.

The discharge current waveform is shown in Figure 21.4. The discharge current waveform is shown in Figure 21.4.

The test is performed with single discharges repeated on The test is performed with single discharges repeated on each test point 10 times with positive polarity and 10 each test point 10 times with positive polarity and 10 times with negative polarity at

times with negative polarity at each test level. each test level. The timeThe time interval between successive discharges is greater than 1 interval between successive discharges is greater than 1 second.

second. Tests are carried Tests are carried out at each level, out at each level, with the relaywith the relay in the following modes of operation:

in the following modes of operation:

1.

1. current and voltage applied at 90% of setting,current and voltage applied at 90% of setting, (relay not tripped)

(relay not tripped) 2.

2. current and voltage applied at 110% of setting,current and voltage applied at 110% of setting, (relay tripped)

(relay tripped) 3.

3. main protection and communications functionsmain protection and communications functions are tested to determine the effect of the discharge are tested to determine the effect of the discharge To pass, the relay shall not maloperate, and shall still To pass, the relay shall not maloperate, and shall still perform its main functions within the claimed tolerance. perform its main functions within the claimed tolerance.

21.3.9 Conducted and Radiated Emissions Tests

These tests arise primarily from the essential protection These tests arise primarily from the essential protection requirements of the European Community (EU) directive requirements of the European Community (EU) directive on EMC.

on EMC. These require mThese require manufacturers to ensure that anufacturers to ensure that anyany equipment to be sold in the countries comprising the equipment to be sold in the countries comprising the European Union must not interfere with other European Union must not interfere with other equipment.

equipment. To achieve this it To achieve this it is necessary to measure is necessary to measure thethe emissions from the equipment and ensure that they are emissions from the equipment and ensure that they are below the specified limits.

below the specified limits.

Conducted emissions are measured only from the Conducted emissions are measured only from the equipment

equipment’’s power supply ports and are to ensure that whens power supply ports and are to ensure that when connected to a mains network, the

connected to a mains network, the equipment does not injectequipment does not inject interference back into the network which could adversely interference back into the network which could adversely affect the other equipment connected to the network. affect the other equipment connected to the network. Radiated emissions measurements are to ensure that the Radiated emissions measurements are to ensure that the interference radiated from the equipment is not at a interference radiated from the equipment is not at a level that could cause interference to other equipment. level that could cause interference to other equipment. This test is normally carried out on an Open Area Test This test is normally carried out on an Open Area Test Site (OATS) where there are no reflecting structures or Site (OATS) where there are no reflecting structures or sources of radiation, and therefore the measurements sources of radiation, and therefore the measurements obtained are a true indication of the emission spectrum obtained are a true indication of the emission spectrum of the

of the relay. relay. An example An example of a of a plot obtained plot obtained duringduring conducted emissions tests is shown in Figure 21.5. conducted emissions tests is shown in Figure 21.5. The test arrangements for the conducted and radiated The test arrangements for the conducted and radiated emissions tests are shown in Figure 21.6.

emissions tests are shown in Figure 21.6.

When performing these two tests, the relay is in a When performing these two tests, the relay is in a quiescent condition, that is not tripped, with currents quiescent condition, that is not tripped, with currents and voltages applied

and voltages applied at 90% of at 90% of the setting values. the setting values. ThisThis is because for the majority of its life, the relay will be in is because for the majority of its life, the relay will be in the quiescent state and the emission of electromagnetic the quiescent state and the emission of electromagnetic interference when the relay is tripped is considered to be interference when the relay is tripped is considered to be of no

of no significance. significance. Tests are Tests are conducted in conducted in accordanceaccordance with IEC 60255-25 and EN 50081-2, and are detailed in with IEC 60255-25 and EN 50081-2, and are detailed in Table 21.3. Table 21.3. • • 2121•• R R e e l l a a y y T T e e s s t t i i n n g g a a n n d d C C o o m m m m i i s s s s i

i o o

n n i i n n g g N e t w o r k P N e t w o r k P r o t e c t i o n & A ur o t e c t i o n & A u t o m a t i o n G u i d et o m a t i o n G u i d e • 3 • 3 77 66 •• CC uu rrrr ee nn tt,, %% oo ff PP ee aa kk Time, ns Time, ns Rise Time = 0.7 to 1.0 Rise Time = 0.7 to 1.0 ns.ns.

Current specified for 30 ns and 60 ns Current specified for 30 ns and 60 ns

10 10 20 20 30 30 40 40 50 50 60 60 70 70 80 80 90 90 100 100 1100 2200 3300 4400 5500 6600 7700 00 00 Figure 21.4:

Figure 21.4: ESD Current WaveforESD Current Waveformm

Table 21.3:

Table 21.3: Test criteria for Test criteria for Conducted and Conducted and

Radiated Emissions tests

FFrreeqquueennccy y RRaannggee SSppeecciiffiieed d LLiimmiittss TTeesst t LLiimmiittss 30 - 230MHz 30 - 230MHz 30dB(µV/m) 30dB(µV/m) _aat_t_3300m_m 40dB(µV/m)40dB(µV/m)_aat_t_1100m_m 230 - 1000MHz 230 - 1000MHz 3377ddB_aat_tB((µ_3300mµVV//m_mm)) 4477ddB_aat_tB((µ_1100mµVV//m_mm)) 0.15 - 0.5MHz 0.15 - 0.5MHz qquuaassii--ppeeaakk7799ddBB((µµVV)) qquuaassii--ppeeaakk7799ddBB((µµVV)) 66

66dB(dB(µV) avµV) avereragagee 66d66dB(B(µV) avµV) avererageage 0.5 - 30MHz

0.5 - 30MHz qquuaassii--ppeeaakk7733ddBB((µµVV)) qquuaassii--ppeeaakk7733ddBB((µµVV)) 60

60dB(dB(µV) aµV) aververagagee 60d60dB(B(µV) aµV) aveveragragee Radiated

Radiated

Conducted Conducted

Chap21-370-397

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i o o

n n i i n n g g N e t w o r k P r N e t w o r k P r o t e c t i o n & A u t oo t e c t i o n & A u t o m a t i o n G u i d em a t i o n G u i d e • 3• 3 77 77 •• 00 EE mm iiss ssii oo nn ss LL ee vv ee ll,, dd BB uu VV Frequency, MHz Frequency, MHz 10 10 20 20 30 30 40 40 50 50 60 60 70 70 80 80 90 90 100 100 00..11 11 1100 110000 Quasi-peak limits Quasi-peak limits Average limits Average limits Typical trace Typical trace Figure 21.5:

Figure 21.5: Conducted Emissions TeConducted Emissions Test Plot st Plot

Screened room Screened room Support/analysis Support/analysis equipment equipment Acc Access paneess panell

Ante-chamber Ante-chamber E.U.T. E.U.T. Impedance network Impedance network

E.U.T. - Equipment under test E.U.T. - Equipment under test E.U.T. E.U.T. Antenna Antenna Tu Turntablerntable Earth Plane Earth Plane 10m 10m (b)

(b) Radiated Emissions test arRadiated Emissions test arrangement on an OATSrangement on an OATS (a) Conducted EMC emissions test

(a) Conducted EMC emissions test arrangementarrangement

Figure 21.6:

Figure 21.6: EMC test arraEMC test arrangements ngements Chap21-370-397

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21.3.1

21.3.10 Conducted 0 Conducted and Radiated Immunity and Radiated Immunity TestsTests

These tests are designed to ensure that the equipment is These tests are designed to ensure that the equipment is immune to levels of interference that it may be subjected immune to levels of interference that it may be subjected to.

to. The two tests, conducted and radiated, The two tests, conducted and radiated, arise from thearise from the fact that for a conductor to be an efficient antenna, it fact that for a conductor to be an efficient antenna, it must have a length of at least 1/4 of the wavelength of must have a length of at least 1/4 of the wavelength of the electromagnetic wave it is required to conduct. the electromagnetic wave it is required to conduct. If a relay were to be subjected to radiated interference at If a relay were to be subjected to radiated interference at 150kHz, then a conductor length of at least

150kHz, then a conductor length of at least

λ

λ ₌₌ 300300 _xx101066_/(_/(150150_xx 101033_xx 44₎₎

=

= 500 m500 m

would be nee

would be needed to condded to conduct the interference. uct the interference. Even withEven with all the cabling attached and with the longest PCB track all the cabling attached and with the longest PCB track length taken into account, it would be highly unlikely length taken into account, it would be highly unlikely that the relay would be able to conduct radiation of this that the relay would be able to conduct radiation of this frequency, and the test therefore, would have no effect. frequency, and the test therefore, would have no effect. The interference has to be physically introduced by The interference has to be physically introduced by conduction, hence the conducted immunity test. conduction, hence the conducted immunity test. However, at the radiated immunity lower frequency limit However, at the radiated immunity lower frequency limit of 80MHz, a conductor length of approximately 1.0m is of 80MHz, a conductor length of approximately 1.0m is required.

required. At this frequencyAt this frequency, radiated , radiated immunity tests canimmunity tests can be performed with the confidence that the relay will be performed with the confidence that the relay will conduct this interference, through a combination of the conduct this interference, through a combination of the attached cabling and the PCB tracks.

attached cabling and the PCB tracks.

Although the test standards state that all 6 faces of the Although the test standards state that all 6 faces of the equipment should be subjected to the interference, in equipment should be subjected to the interference, in practice this is not

practice this is not carried out. carried out. Applying interference toApplying interference to the sides and top and bottom of the relay would have the sides and top and bottom of the relay would have little effect as the circuitry inside is effectively screened little effect as the circuitry inside is effectively screened by the earthed

by the earthed metal case. metal case. However, However, the front and the front and rearrear of the relay are not completely enclosed by metal and are of the relay are not completely enclosed by metal and are therefore not at all well screened, and can be regarded as therefore not at all well screened, and can be regarded as an

an EMC EMC hole. hole. Electromagnetic Electromagnetic interference interference whenwhen directed at the front and back of the relay can enter directed at the front and back of the relay can enter freely onto the PCB

freely onto the PCB’’s inside.s inside.

When performing these two tests, the relay is in a When performing these two tests, the relay is in a quiescent condition, that is not tripped, with currents quiescent condition, that is not tripped, with currents and voltages applied

and voltages applied at 90% of at 90% of the setting values. the setting values. ThisThis is because for the majority of its life, the relay will be in is because for the majority of its life, the relay will be in the quiescent state and the coincidence of an the quiescent state and the coincidence of an electromagnetic disturbance and a fault is considered to electromagnetic disturbance and a fault is considered to be unlikely.

be unlikely.

However, spot checks are performed at selected However, spot checks are performed at selected frequencies when the main protection and control frequencies when the main protection and control functions of the relay are exercised, to ensure that it will functions of the relay are exercised, to ensure that it will operate as expected, should it be required to do so. operate as expected, should it be required to do so. The frequencies for the spot checks are in general The frequencies for the spot checks are in general selected to coincide with the radio frequency broadcast selected to coincide with the radio frequency broadcast bands, and in particular, the frequencies of mobile bands, and in particular, the frequencies of mobile communications equipment used by personnel working communications equipment used by personnel working in the substation.

in the substation. This is to ensure This is to ensure that when working inthat when working in the vicinity of a relay, the personnel should be able to the vicinity of a relay, the personnel should be able to

operate their radios/mobile phones without fear of relay operate their radios/mobile phones without fear of relay maloperation.

maloperation.

IEC 60255-22-3 specifies the radiated immunity tests to IEC 60255-22-3 specifies the radiated immunity tests to be conducted (ANSI/IEEE C37.90.2 is used for equipment be conducted (ANSI/IEEE C37.90.2 is used for equipment built to US standards), with signal levels of:

built to US standards), with signal levels of: 1.

1. IEC: IEC: Class III, 1Class III, 10V/m, 80MHz 0V/m, 80MHz -1000MHz-1000MHz 2.

2. ANSI/IEEE: ANSI/IEEE: 35V/m 35V/m 25MHz 25MHz - 1- 1000MHz 000MHz with nowith no modulation, and again with 100% pulse modulation, and again with 100% pulse modulation

modulation

IEC 60255-22-6 is used for the conducted immunity test IEC 60255-22-6 is used for the conducted immunity test ,, with a test level of:

with a test level of:

Class III, 10V r.m.s., 150kHz - 80MHz. Class III, 10V r.m.s., 150kHz - 80MHz.

21.3.11 Power Frequency Magnetic Field Tests

These tests are designed to ensure that the equipment is These tests are designed to ensure that the equipment is immune

immune to to magnetic magnetic interference. interference. The The three three tests,tests, steady state, pulsed and damped oscillatory magnetic steady state, pulsed and damped oscillatory magnetic field, arise from the fact that for different si

field, arise from the fact that for different si te conditionste conditions the level and waveshape is altered.

the level and waveshape is altered.

23.3.1

23.3.11.1 Steady state magnetic 1.1 Steady state magnetic field tests field tests

These tests simulate the magnetic field that would be These tests simulate the magnetic field that would be experienced by a device located within

experienced by a device located within close proximity of close proximity of the power

the power system. system. Testing is Testing is carried out by carried out by subjectingsubjecting the relay to a magnetic field generated by two induction the relay to a magnetic field generated by two induction coils.

coils. The relay is The relay is rotated such that rotated such that in each axis in each axis it isit is subjected to the full

subjected to the full magnetic field strength. magnetic field strength. IEC 61IEC 61000- 000-4-6 is the relevant standard, using a signal level of: 4-6 is the relevant standard, using a signal level of: Level 5: 300A/m continuous and 1000A/m short duration Level 5: 300A/m continuous and 1000A/m short duration The test arrangement is shown in Figure 21.7.

The test arrangement is shown in Figure 21.7.

i o o

n n i i n n g g N e t w o r k P N e t w o r k P r o t e c t i o n & A ur o t e c t i o n & A u t o m a t i o n G u i d et o m a t i o n G u i d e • 3 • 3 77 88 •• E.U.T. E.U.T. Induction coil Induction coil Induction coil Induction coil Ground plane Ground plane

E.U.T. - Equipment under test E.U.T. - Equipment under test

Figure 21.7:

Figure 21.7: Power freqPower frequency magnetic uency magnetic

field set-up

field set-up Chap21-370-397