Toshiba GR-200 Series Instruction Manual page 253

Outline
2.22.1
The ARC function provides the following features mainly for sub-transmission and distribution
lines:
1. Three-phase autoreclosing command, this can be issued upon the reception of a trip
signal from the trip circuit (TRC) designed for three-phase tripping. Note that the ARC
function here is not designed to reclose the CB on a per-phase tripping basis. The ARC
function will operate regardless of the faulted phases, whether it is for a single-phase
fault or a multi-phase fault.
2. Evaluation for successful autoreclosing operation, an autoreclosing failure is
determined when the CB fails to close when the ARC function is in progress
3. Single-shot/Multi-shot schemes are provided; it is possible to set autoreclose shot
numbers from 'shot1 to shot5' for the multi-shot scheme. For the single-shot scheme,
the shot number is set to 'shot1'.
4. Permissive voltage check and check synchronism, the reclosing command for 'shot1' is
issued following the reception of a permissive signal from the voltage check function
(VCHK), this function checks for the existence, absence and synchronism of voltages on
the line. The user can program the generation of the permissible signal using settings
in the VCHK function.
5. Shot number coordination, if as shown in Figure 2.22-1, we consider two circuit
breakers, CB
busbar H, the shot number coordination function will enable the matching of the shot
number between Relay
For example, two coordination steps are executed, as follows:
Step1:
Two instantaneous trips and two subsequent reclosures for CB
ensures the integrity and reliability of the power system for temporary faults.
Step2:
One coordinated IDMT/DT time delayed trip is performed for the CBs by Relay
Relay . Coordinated tripping provides time delayed clearing of a semi-permanent
(H)
Fault F, which may be caused by a foreign object that has fallen across the line (e.g. a
twig from a tree branch), and which may be burnt out/dislodged to clear the fault.
During step2 of the scheme above, Relay
and CB on a radial distribution feeder, and a fault occurs remote from
(G) (H)
and Relay
(G)
- 234 -
for a fault occurring downstream of busbar H.
(H)
should not incorrectly determine that the
(G)
6F2T0200 (0.15)
and CB . Step1
(G) (H)
and
(G)
GRE200 (1,2)