Toshiba GR-200 Series Instruction Manual page 254

auto-reclose was successful, i.e. 'ARC close success' and reset its ARC function. Shot
number coordination ensures that this does not occur and synchronizes the shot
numbers of Relay
Busbar G
Figure 2.22-1 Semi-temporary Fault F and locations of relays
Terminology
2.22.2
Relay operation period
(i)
The time interval commencing from the instant of the relay picking-up for the fault current to
the instant of the relay dropping-off following the cessation of the fault current.
Temporary/transient/Arc fault
(ii)
A temporary/transient fault, the main cause of which is often due to lightning, (an over voltage
induced in a line due to the static electricity caused by the lightning may cause a flash over
across the insulator string), temporary contact with foreign objects, conductor clashing as a
consequence of strong wind.
Arcing time of CB
(iii)
When 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 called
the 'Arcing time', which is the time between the instant of separation of the circuit breaker
contacts and the instant of the extinction of the fault arc.
Permanent fault (signal 'ARC FT')
(iv)
Fallen conductors, tree growth, tree branches that have fallen across lines, as well as other
causes, may all produce permanent faults. As the operation of the ARC function is unable to
restore power transmission for permanent faults, the ARC function abandons the reclosing of
the CB, defined as the 'Final trip (FT)' stage. If the ARC function gets into the FT stage, closing
the CB is only possible by the manual operation.
Signal shot scheme (signal 'ARC SHOT1')
(v)
The ARC function issues a first auto-reclosing signal 'ARC SHOT1' when a 'GEN.TRIP' signal
is issued in the trip circuit (TRC) by the first relay operation. When the user programs the
ARC function not to provide subsequent reclosures, this operating sequence provides only one
reclosing operation; then, lockout will occur on subsequent tripping, i.e. the 'Final trip (FT)'
and Relay .
(A) (H)
Busbar H
CB
Relay
(G)
- 235 -
Semi-temporary Fault F
CB
Relay (H)
6F2T0200 (0.15)
GRE200 (1,2)