Toshiba GR-200-5 Instruction Manual

Also see for GR 200 Series: Instruction manual Instruction manual Instruction manual Instruction manual Instruction manual

6F2T0207 (0.01)GRE200 (5,6)- 248 -Busbar G Permanent Fault FRelay OCG in DTG(1), DTG(2), IDMTG(3), IDMTG(4)GFuseLateral branchSSectionalizerLateral branchFuseMain feederARCRARCRelay OCR in DTR(1), DTR(2), IDMTR(3), IDMTR(4)Figure 2.22-15 Occurrence of fault and OC operations with ARC†Note:Delayed trip commands following the instantaneous trip commands may be usedfor realizing time coordination between the relays, sectionalizers and fuses.Upon the occurrence of a permanent fault ‘F’, both relays G and R will issue a DT(2) tripfollowing a DT(1) trip for their respective CBs; that is, in the first instance a reclose shot, (ARCSHOT1) will be issued by both relays. Then, a second reclose shot (ARC SHOT2) will also beissued by both the relays.For the third reclose shot (ARC SHOT3), the difference between the settings of theIDMT(3) characteristic for relays G and R will alter the operating times of their respective ARCfunctions. Given that the pickup time in IDMTG(3) is delayed in comparison to the pickup timein IDMTR(3), the third reclosing (ARC SHOT3) will be performed only by relay R, whereas relayG neither issues a trip command nor an ARC shot. Consequently, relay G may now determinethat the operation of its ARC sequence has been successful and hence relay G will reset toreturn to the beginning of its sequence ‘ARC ready’ (i.e. the ARC function at relay G willcommence from the first reclose shot ‘ARC SHOT1’). Conversely, relay R is unable to issue afourth reclose shot (ARC SHOT4) because the delayed operation of IDMTR(4) means that it willnot have sufficient time to operate for the fault. This is because, following the tripping for thefirst DTG(1), relay G issues the first reclose shot (ARC SHOT1), but its shot sequence is notcorrect. Figure 2.22-16 illustrates how tripping and reclosing are not performed correctly; thuserroneous coordination between the ARC operations at relay G and relay R is experienced.