Toshiba GR-200-5 Instruction Manual page 274

ARC maximum shot number ([ARC-NUM]=S2)
Set to two (S2) shots, as CB is capable of only two successive reclosures.
ARC reclaim time ([TREADY]): 35.0 seconds
The ARC ready logic requires the CB to be in the closed position with CB ARC ready (e.g.
closing spring is charged, SF6 gas pressure OK).
When a CB is closed for the first time subsequent to the maintenance of a distribution
line, the closure should be successful (that is, the CB is closed on to healthy line). Then the
minimum time setting of the TREADY timer should be longer than the time required to judge
that the CB has closed successfully; say a setting of 5 seconds will be appropriate.
Another consideration is, for the setting required after the CB has gone through a
successful ARC cycle and the maximum allowable successive close-open operations have been
used. In this case, the minimum time delay required before the CB is ready for the next ARC
cycle becomes the setting criteria for the [TREADY] timer. In the example considered, this
minimum time delay is 30 seconds so in order to provide some margin a setting of 35.0 seconds
has been chosen.
Dead time for first shot ([TSHOT] / [TSHOT_SUB]): 0.13s
Dead time for the first shot using the following equations:
A=CB⁡opening⁡time⁡+⁡Deionizing⁡time-CB⁡closing⁡time
B=CB⁡opening⁡time⁡+⁡Protection⁡reset⁡time
C=CB⁡opening⁡time⁡+⁡Trip⁡mechanism⁡reset⁡time
D=CB⁡opening⁡time⁡+⁡Minimum⁡dead⁡time⁡required⁡by⁡CB⁡before⁡Shot1 (2.22-4)
If the A to D values were calculated using Equations (2.22-1) to (2.22-4)
A= (60ms + 125ms – 80ms) = 105ms
B= (60ms + 30ms) = 90ms
C= (60ms + 0) = 60ms
D= (60ms + 0) = 60ms
The maximum of A, B, C, D would be A; therefore the [TSHOT] setting = A + margin = 105ms
+ 20ms = 125ms.
Note: The user can choose [TSHOT_SUB] using PLC signals ARC_SUB_START and
- 254 -
6F2T0207 (0.01)
(2.22-1)
(2.22-2)
(2.22-3)
GRE200 (5,6)