Toshiba GR-200-5 Instruction Manual

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6F2T0207 (0.01)GRE200 (5,6)- 234 -auto-reclose was successful, i.e. ‘ARC close success’ and reset its ARC function. Shotnumber coordination ensures that this does not occur and synchronizes the shotnumbers of Relay(A) and Relay(H).Busbar G Busbar H Semi-temporary Fault FCBRelay(H)CBRelay(G)Figure 2.22-1 Semi-temporary Fault F and locations of relays2.22.2 Terminology(i) Relay operation periodThe time interval commencing from the instant of the relay picking-up for the fault current tothe instant of the relay dropping-off following the cessation of the fault current.(ii) Temporary/transient/Arc faultA temporary/transient fault, the main cause of which is often due to lightning, (an over voltageinduced in a line due to the static electricity caused by the lightning may cause a flash overacross the insulator string), temporary contact with foreign objects, conductor clashing as aconsequence of strong wind.(iii) Arcing time of CBWhen the CB contacts separate during tripping, an arc is produced between the CB contacts;the arc is extinguished by the interrupting medium in the CB. The duration of arcing is calledthe ‘Arcing time’, which is the time between the instant of separation of the circuit breakercontacts and the instant of the extinction of the fault arc.(iv) Permanent fault (signal ‘ARC FT’)Fallen conductors, tree growth, tree branches that have fallen across lines, as well as othercauses, may all produce permanent faults. As the operation of the ARC function is unable torestore power transmission for permanent faults, the ARC function abandons the reclosing ofthe CB, defined as the ‘Final trip (FT)’ stage. If the ARC function gets into the FT stage, closingthe CB is only possible by the manual operation.(v) Signal shot scheme (signal ‘ARC SHOT1’)The ARC function issues a first auto-reclosing signal ‘ARC SHOT1’ when a ‘GEN.TRIP’ signalis issued in the trip circuit (TRC) by the first relay operation. When the user programs theARC function not to provide subsequent reclosures, this operating sequence provides only onereclosing operation; then, lockout will occur on subsequent tripping, i.e. the ‘Final trip (FT)’