EDS 05-2011 Air Circuit Breaker Protection Settings
Document Number: EDS 05-2011Date: 11/06/2018ENGINEERING DESIGN STANDARDEDS 05-2011AIR CIRCUIT BREAKER PROTECTION SETTINGSNetwork(s):EPN, LPN, SPNSummary:This standard details the current and previous protection settings used on LV aircircuit breakers used on the EPN, LPN and SPN networks.Author:Jesse GarciaDate:11/06/2018Approver:Paul WilliamsDate:06/08/2018This document forms part of the Company's Integrated Business System and its requirements are mandatory throughout UKPower Networks. Departure from these requirements may only be taken with the written approval of the Director of AssetManagement. If you have any queries about this document please contact the author or owner of the current version.CirculationUK Power NetworksExternal Asset Management UK Power Networks Services Capital Programme Contractors Connections ICPs/IDNOs Health & Safety Meter Operators Legal G81 Website Network Operations Procurement Strategy & Regulation Technical TrainingTHIS IS AN UNCONTROLLED DOCUMENT, THE READER MUST CONFIRM ITS VALIDITY BEFORE USEVersion: 5.0
Air Circuit Breaker Protection SettingsDocument Number: EDS 05-2011Version: 5.0Date: 11/06/2018Revision RecordVersion5.0Review Date06/08/2023Date20/06/2018AuthorJesse GarciaReason for update: Periodic review, change of type of HV TLF fuses available.What has changed: Concentrated all settings on a single table. Updated protection curve diagrams.Removed Appendix C.Version4.0Review Date03/06/2018Date13/05/2015AuthorJesse GarciaReason for update: Periodic reviewWhat has changed – Section 3.1 updated to include 10A tagged TLF, Section 3.2 title updated toinclude EPN and SPN, Sections 3.2.2, 3.2.3 and 3.2.4 - tables referencing RMU TLF Fuse (A)updated, Section 5 reference list updated.Version3.0Review Date24/04/2015Date19/03/2012AuthorDamien DeleaReclassification of document from EI 05-2011. Document reviewed. All protection settings revised,customer discrimination and grading curves added.Version2.0Review DateDate07/08/2007AuthorD J CollisUpdate to current protection settings – Section 6.Version1.1Review DateDate16/07/2007AuthorD J CollisSection 6.1.1 Iinst 6 changed to Iinst 15.Section 6.1.2 Iinst 8 changed to Iinst 15.Version1.0Review DateDate12/06/2005AuthorD J CollisOriginal. UK Power Networks 2018 All rights reserved2 of 24
Air Circuit Breaker Protection SettingsDocument Number: EDS 05-2011Version: 5.0Date: 11/06/2018Contents1Introduction . 52Scope . 53Glossary and Abbreviations . 54Protection Settings for New ACBs . 54.1General . 54.2ACB protection settings for all Micrologic 5.0. . 84.3Reverse Power Relays . 95Protection Settings for Legacy ACBs . 95.1Schneider Electric NW20H1 (2007-2011) . 95.2Merlin Gerin NW25H1 and NT16H1 (EPN 2003 to 2007) . 105.3Merlin Gerin NW16H1 and NW20H1 (LPN 2003 to 2007). 105.4Merlin Gerin NS1250 (EPN 2003 onwards) . 115.5Merlin Gerin M16H1 (EPN 1993 to 2003) . 115.6Merlin Gerin M25 (EPN 1993 to 2003) . 125.7Merlin Gerin M16 and M25 (EPN 1991 to 1993) . 125.8Merlin Gerin M16 and M25 (EPN 1991 to 1993) . 135.9Merlin Gerin C1250N and C1251N (EPN 1988 to 1992) . 135.10Dorman Smith 600A and 1250A MCCB (before 1988) . 146References . 146.1UK Power Networks Standards . 14Appendix A – Protection Settings Explained . 15A.1Schneider Electric Micrologic Protection Modules . 15A.2Merlin Gerin (or Schneider Electric) STR38ST Trip Unit Settings . 15A.3Dorman Smith Trip Units . 15Appendix B - AMTECH Protection Curves . 16B.111kV 500kVA Transformer ACB 1600A rating . 16B.211kV 500kVA Transformer ACB 2000A rating . 17B.311kV 750kVA Transformer ACB 1600A rating . 18B.411kV 750kVA Transformer ACB 2000A rating . 19B.511kV 800kVA Transformer ACB 1600A rating . 20B.611kV 800kVA Transformer ACB 2000A rating . 21B.711kV 1000kVA Transformer ACB 1600A rating . 22B.811kV 1500kVA Transformer ACB 2500A rating . 23B.911kV 1500kVA Transformer ACB 2500A rating . 24 UK Power Networks 2018 All rights reserved3 of 24
Air Circuit Breaker Protection SettingsDocument Number: EDS 05-2011Version: 5.0Date: 11/06/2018FiguresFigure 4-1 - Large LV supply from network feeding substation . 6TablesTable 1 ACB protection settings . 8 UK Power Networks 2018 All rights reserved4 of 24
Air Circuit Breaker Protection SettingsDocument Number: EDS 05-2011Version: 5.0Date: 11/06/20181IntroductionThis standard details the protection settings for LV Air Circuit Breakers (ACB) and includessettings for new and legacy ACBs.This standard has been updated to meet the requirements for large customer LV suppliesdetailed in UK Power Networks EDS 08-2100 LV Customer Supplies.2ScopeThis standard applies to all ACBs on UK Power Networks EPN, LPN and SPN networks.3Glossary and AbbreviationsTermDefinitionACBAir Circuit BreakersTLFTime Fuse LinkTS&STechnical Sourcing and StandardsRMURing Main UnitLVLow VoltageHVHigh VoltageUK Power NetworksUK Power Networks (Operations) Ltd consists of three electricitydistribution networks: Eastern Power Networks plc (EPN). London Power Network plc (LPN). South Eastern Power Networks plc (SPN).4Protection Settings for New ACBs4.1GeneralA common range of ACBs are available and are used to provide large supplies to LVcustomers or supply the LPN interconnected network (with reverse power relays). Refer to UKPower Networks EDS 08-0803 for further information on their application.The approved ranges of ACBs are supplied by Schneider Electric and are fitted with aMicrologic 5.0A protection module to provide overcurrent protection. Refer to the relevantEngineering Approval Standard for the current range of approved ACBs.The ACB protection settings in section 4.2 have been selected to provide the bestdiscrimination between the network LV distribution board on which there are large BS88 J typefuses to customers.The protection settings for various ACBs and various sizes of transformer to discriminate witha 15A or 12.5A tagged TLF, used for transformer HV overcurrent protection, are given in thesections that follow. The tagged type TLFs shall be used in conjunction with LV ACBs to allowfor discrimination in settings. An explanation of the various settings is given in appendix A andthe associated AMTECH curves are included in Appendix B. UK Power Networks 2018 All rights reserved5 of 24
Air Circuit Breaker Protection SettingsDocument Number: EDS 05-2011Version: 5.0Date: 11/06/2018If the standard settings are not suitable due to network variations please contact UK PowerNetworks Asset Management for site specific settings.A network variation example is when a customer has an ACB to protect their site. Thecustomer shall attempt to grade with UK Power Networks standard settings, however if theyhave difficulties they might request a variation in settings. This case shall be investigated bythe Asset Management – Technical Standards protection engineers and only with theirpermission variation from standard settings will occur.Note: The Micrologic protection module is pre-set with the protection settings for a750/800/1000kVA transformer by the supplier. The Micrologic 6.0A is not suitable for use on the LPN network and care should be takenwhen it is used on the other networks as the earth fault settings may not provide sufficientdiscrimination or co-ordination with downstream fusing. Figure 4.1 below presents an example of an ACB supply to a distribution board and a LargeLV Supply customer.Ring Main UnitSwitch inOPEN positionEnd boxBus barSwitch inON positionHV circuitbreakerHV cableTi me l im itfuse sHV CB with overcurrentand earth fault protection(TLF shunted trip coils)Transformer ChamberarrangementTransformerHV CBintertripsACBOwnership BoundaryUK Power NetworksTrip barLV ACB with direct acting overcurrentCustomer(with Reverse Power Relay forLPN interconnected network)LARGE LV SUPPLY2000Amp LV air circuitbreaker (ACB)1600Amp ACB with meteringCT’sLV Network fused feeder waysDistr ibutorsFigure 4-1 - Large LV supply from network feeding substation UK Power Networks 2018 All rights reserved6 of 24
Air Circuit Breaker Protection SettingsDocument Number: EDS 05-2011Version: 5.0Date: 11/06/2018Due to the obsolescence of glass barrel type fuses and the adoption of XF TLF fuses, timegrading on the 6.6kV network has become difficult and the possibility of ACB protectionoperating faster than an LV Fuse is larger. As such it is important for operational staff to followthe instructions on HSS 40 017 when re-energizing devices.There is an ongoing investigation by the Asset Management TS&S team to adopt RMUs wherethe HV transformer protection is provided by an IDMT capable relay instead of an XF TLF fusefor secondary substations that have ACBs. If the proposal is adopted, this document shall beupdated. UK Power Networks 2018 All rights reserved7 of 24
Air Circuit Breaker Protection SettingsDocument Number: EDS 05-2011Version: 5.0Date: 11/06/20184.2ACB protection settings for all Micrologic 5.0.Note: The settings below are applicable to all Micrologic 5.0 ACBs, protection modules,including large single service customers.11Largest possible LV fuse (A)ACB Protection 0.2105001500250015.00.800.28N/A100/512.5Micrologic 5.0A1600RMU TLF Fuse (A)500RMU CT RatioACB Rating (A)6.6tsd( i2t)Transformer (kVA)System Voltage (kV)Table 1 ACB protection settings UK Power Networks 2018 All rights reservedIr0.70tr4Isd48 of 24
Air Circuit Breaker Protection SettingsDocument Number: EDS 05-2011Version: 5.0Date: 11/06/20184.3Reverse Power RelaysOn the LV interconnected network in the LPN area, reverse power relays are used to detectreverse power flow caused by a fault on the HV side of the transformer and trip the ACB toprevent back feed from the LV side. Over-current protection is not required on these ACBs.There are two types of relay used: The English Electric CAG with a PCD directional element;The Reyrolle TGG relay.Both relays have fixed settings that are set to trip at roughly three times the LV current withthe secondary set at 10A.5Protection Settings for Legacy ACBsThis section details the protection settings for legacy ACBs used on the EPN, LPN and SPNnetworks between 1st July 2007 and 31st December 2011.If the HV TLF fuses are replaced with new ones on an ACB with Micrologic 5.0 protection thenthe settings shall be changed to the ones presented I previously in chapter 4.2. If the HV TLFfuses are replaced with new ones on an ACB with Micrologic 6.0, please contact UK PowerNetworks Asset Management for site specific settings.Note: ACBs were introduced in SPN in 2007.5.1Schneider Electric NW20H1 (2007-2011)ACBNW20H1System Voltage (kV)1111Transformer (kVA)1000, 800, 750500RMU CT Ratio100/550/5RMU TLF Fuse (A)1515ACB Protection ModuleMicrologic 6.0A/6.0PMicrologic 6.0A/6.0PMicrologic 6.0A/6.0PACB Protection SettingsIr 1Ir 0.6Ir 0.7tr 4tr 4tr 4Isd 4Isd 4Isd 4tsd 0.1 I2ttsd 0.1 I2ttsd 0.1 I2tIinst 15Iinst 15Iinst 15Ig Ig Ig tg tg tg UK Power Networks 2018 All rights reserved6.69 of 24
Air Circuit Breaker Protection SettingsDocument Number: EDS 05-2011Version: 5.0Date: 11/06/20185.2Merlin Gerin NW25H1 and NT16H1 (EPN 2003 to 2007)The Merlin Gerin NW25H1 was used with 1500kVA and 1000kVA transformers. The MerlinGerin NT16H1 is only used with 1000kVA transformers. Note: These units have been selectedto cope with 130% overload conditions.ApplicationLarge supplies to LV 00kVA1000kVAProtection ModuleMicrologic 6.0AMicrologic 6.0AMicrologic 6.0AProtection SettingsIr 0.9Ir 0.7Ir 1tr 8tr 8tr 8Isd 2Isd 2Isd 3tsd 0.2 I2ttsd 0.2 I2ttsd 0.3 I2tIi 12Ii 12Ii 12tg 0.4 I2t ONtg 0.4 I2t ONtg 0.4 I2t ON5.3Merlin Gerin NW16H1 and NW20H1 (LPN 2003 to 2007)The Merlin Gerin NW16H1 was used with 800kVA transformers and below. The Merlin GerinNW20H1 was used with 1000kVA transformers. Note: These units have been selected tocope with 160% overload conditions.ApplicationLarge supplies to LV customers or network support for the kVA and below1000kVAProtection ModuleMicrologic 5.0AMicrologic 5.0AProtection SettingsIr 1Ir 1tr 4tr 4Isd 6Isd 8tsd 0.1 I2ttsd 0.1 I2tIinst 15Iinst 15 UK Power Networks 2018 All rights reserved10 of 24
Air Circuit Breaker Protection SettingsDocument Number: EDS 05-2011Version: 5.0Date: 11/06/20185.4Merlin Gerin NS1250 (EPN 2003 onwards)The Merlin Gerin NS1250 was used with 500kVA and 700 kVA transformers. Note: This unithas been selected to cope with 130% overload conditions.ApplicationLarge supplies to LV tection ModuleMicrologic 5.0AMicrologic 5.0AProtection SettingsIr 0.9Ir 1tr 8tr 8Isd 2.5Isd 5tsd 0.3 I2ttsd 0.3 I2tIi 15Ii 155.5Merlin Gerin M16H1 (EPN 1993 to 2003)The Merlin Gerin M16H1 was used with 1000kVA transformers. Note: This unit has beenselected to cope with 130% overload conditions.ApplicationLarge supplies to LV customersACBM16H1Transformer1000kVAProtection ModuleSTR38STProtection SettingsIo 1Ir 1Im 3tm 0.3 I2t ONIi max/ON (any position in shaded area)Ih 500th 0.4 I2t ONMinimum tripping current 1680ANote: Current in excess of the minimum tripping currents may trip the circuit-breaker after 200s. The STR38ST trip units used on Masterpact ACBs from 1993 may be unstable and maygive nuisance tripping on low loads if Ih is set to less than 500A. UK Power Networks 2018 All rights reserved11 of 24
Air Circuit Breaker Protection SettingsDocument Number: EDS 05-2011Version: 5.0Date: 11/06/20185.6Merlin Gerin M25 (EPN 1993 to 2003)The Merlin Gerin M25 was used with 1500kVA and 1000kVA transformers. Note: This unithas been selected to cope with 130% overload conditions.ApplicationLarge supplies to LV ion ModuleSTR38STSTR38STProtection SettingsIo 1Io 0.63Ir 0.9Ir 1Im 2Im 2tm 0.2 I2t ONtm 0.2 I2t ONI max/ON (any position in shadedarea)I max/ON (any position in shadedarea)Minimum tripping current 2360AMinimum tripping current 2360ANote: Current in excess of the minimum tripping current may trip the circuit-breaker after 200s. The STR38ST trip units used on Masterpact ACBs from 1993 may be unstable and maygive nuisance tripping on low loads if Ih is set to less than 500A.5.7Merlin Gerin M16 and M25 (EPN 1991 to 1993)The Merlin Gerin M16 was used with 1000kVA transformers and the Merlin Gerin M25 wasused with 1500kVA and 1000kVA transformers. Note: These units have been selected to copewith 130% overload conditions.ApplicationLarge supplies to LV kVAProtection ModuleSTR308STSTR38STSTR38STProtection SettingsIr 1Ir 0.9Ir 0.63Im 3Im 2.5Im 2.5tm 0.3tm 0.3tm 0.3Ih 0.2Ih 0.2Ih 0.2Minimum trippingcurrent 1680AMinimum trippingcurrent 2360AMinimum trippingcurrent 2360ANote: Current in excess of the minimum tripping currents may trip the breaker after 200s. UK Power Networks 2018 All rights reserved12 of 24
Air Circuit Breaker Protection SettingsDocument Number: EDS 05-2011Version: 5.0Date: 11/06/20185.8Merlin Gerin M16 and M25 (EPN 1991 to 1993)The Merlin Gerin M16 was used with 1000kVA transformers and the Merlin Gerin M25 wasused with 1500kVA and 1000kVA transformers. Note: These units have been selected to copewith 130% overload conditions.ApplicationLarge supplies to LV kVAProtection ModuleSTR308STSTR38STSTR38STProtection SettingsIr 1Ir 0.9Ir 0.63Im 3Im 2.5Im 2.5tm 0.3tm 0.3tm 0.3Ih 0.2Ih 0.2Ih 0.2Minimum trippingcurrent 1680AMinimum trippingcurrent 2360AMinimum trippingcurrent 2360ANote: Current in excess of the minimum tripping currents may trip the breaker after 200s.5.9Merlin Gerin C1250N and C1251N (EPN 1988 to 1992)The Merlin Gerin C1250N and C1251N were used with 500kVA and 700kVA transformers.Note: These units have been selected to cope with 130% overload conditions.ApplicationLarge supplies to LV kVA700kVA500kVA700kVAIo 1Io 1Ir 0.8Ir 1Ir 0.9Ir 1Im 4Im 5Im 2.5Im 6tm 0.3tm 0.3 I2tONtm 0.3 I2t ONtm 0.3Protection SettingsProtection Settings UK Power Networks 2018 All rights reserved13 of 24
Air Circuit Breaker Protection SettingsDocument Number: EDS 05-2011Version: 5.0Date: 11/06/20185.10Dorman Smith 600A and 1250A MCCB (before 1988)The Dorman Smith 600A and 1200A MCCBs were used with 500kVA and 700kVAtransformers respectively.ApplicationLarge supplies to LV tion Module600A Tripping Unit Type A1250A Tripping Unit Type BThermal Over Load SettingNo. 5No. 4Instantaneous Magnetic ReleaseHighHigh6References6.1UK Power Networks StandardsEDS 08-2100LV Customer SuppliesHSS 40 017Low Voltage Re-Energising Devices UK Power Networks 2018 All rights reserved14 of 24
Air Circuit Breaker Protection SettingsDocument Number: EDS 05-2011Version: 5.0Date: 11/06/2018Appendix A – Protection Settings ExplainedThis appendix provides a brief explanation of the protection settings used on the variousprotection modules.A.1Schneider Electric Micrologic Protectio
This standard details the protection settings for LV Air Circuit Breakers (ACB) and includes . This standard has been updated to meet the requirements for large customer LV supplies detailed in UK Power Networks EDS 08-2100 LV Customer Supplies. 2 Scope This standard applies to all ACBs on UK Power Networks EPN, LPN and SPN networks.
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