Ground Fault Protection - engineering site - Schneider Electric

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Study of MultisourceSystemsIn shortThe multisource / one grounding diagramis characterised by a PEN on theincoming link(s:b the diagram normally used is diagram 2(grounding is symmetrical and performedat coupling level)b diagrams 1 and 3 are only used insource coupling.DB1172844.1. A multisource system with a singleearthingThese systems are not easily constructed nor maintained in the case of extension:second earthings should be avoided. Only one return path to the source exists:b for natural neutral currentsb for PE fault currents.There are 3 types of diagram (figure 25):DB117285DB117286Characteristics of diagram 2Ground fault protection may be:b of the SGR typeb of the RS type if uncoupling of the loadNeutral is performed properlyb the incoming circuit-breakers are of thethree-pole type.Fault management does not requireground fault protection on the coupler.Characteristics of diagrams 1 and 3These diagrams are not symmetrical.They are advantageous only when usedin source coupling with a GE as areplacement source.Diagram 1 Diagram 2 Diagram 3Diagram 25Diagram 2 is the only one used in its present state.Diagrams 1 and 3 are only used in their simplified form:b load U2 (diagram 1) or U1 (diagram 3) absentb no Q3 coupling.The study of these diagrams is characterised by a PEN on the incoming link(s).Consequently, the incoming circuit-breakers Q1 and Q2 must be of the three-poletype.4.1.1. Diagram 2Once earthing of the neutral has been carried out using a distribution neutralConductor, the neutral on supply end protection devices is thus considered to be aPEN. However, the earthing link is a PE.DB117287Diagram 26aReminder of the coding system used:NeutralP EP E N24
4.1.1.1. Study 1 / diagram 2The supply end earth protection device can be implemented using GFP devices ofthe Source Ground Return type of which the measuring CTs are installed on this link(see diagram 26b).DB117288Diagram 26b - "Source Ground Return" type systemIn normal N operation:b a 0 is verified because it deals with a PEb a 1 a 2 are verified as well (currents in the neutral conductor cannot flow in the PEand the earth circuits)b b 1 is verifiedb b 2 is not verified because it deals with a PE common to 2 parts of the installationb b 3 can be verified without any problems.Implemented GFP devices ensure installation safety because maximum leakagecurrent for both installations is always limited to 1200 A.But supply is interrupted because an insulation fault leads to deenergisation of theentire installation.For example, a fault on U2 leads to the deenergisation of U1 and U2.In R1 or R2 replacement operation:All operation criteria are verified.To completely resolve the problem linked to b 2 criterion, one can:b implement a CT coupling system (Study 2)b upgrade the installation system (Study 3).25
Page 1: Low voltage expert guidesGround Fau
Page 5 and 6: The role of “Ground FaultProtecti
Page 8 and 9: 1.2.1.2. Protection using an RCDRCD
Page 10 and 11: 1.2.2.2. Protection using GFP devic
Page 14 and 15: In shortDiscrimination between grou
Page 16 and 17: 2.2.3. ZSI logical discriminationZS
Page 18 and 19: In shortProtection using GFP device
Page 20 and 21: GFP implementationIn shortCorrect i
Page 22 and 23: In short3.2. Operating precautionsT
Page 24 and 25: In short3.3. Applications3.3.1. Met
Page 28 and 29: 4.1.1.2. Study 2 / diagram 2Seeing
Page 30: In R1 (or R2) replacement operation
Page 33 and 34: In event of a fault on the loads 1,
Page 35 and 36: Same operating principle as for stu
Page 37 and 38: 5.2.2. Multisource / single-ground
Page 39 and 40: Installation and implementationof G
Page 41 and 42: DB117297External transformer (CT) f
Page 43 and 44: External transformer (CT) forresidu
Page 45 and 46: Ground fault protectionwith Compact
Page 48 and 49: Implementation in the installationD
Page 50 and 51: Study of discrimination betweenGFPT
Page 52: Study of ZSI discriminationDB117336
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