Toshiba GRL150-100 Series Instruction Manual page 15

Current change detection element OCD
The OCD operates if the vectorial difference between currents I M and I N observed one cycle apart
is larger than the fixed setting. Therefore, the operating sensitivity of this element is not affected
by the quiescent load current and can detect a fault current with high sensitivity.
The operation decision is made according to the following equation:
⏐I M - I N ⏐ > I s
where,
I M = present current
I N = current one cycle before
I s = fixed setting (8% of rated current)
2.2.4 Open Terminal (Out-of-Service) Detection
Erroneous current data may be transmitted from the remote terminal when the remote relay is
out-of-service for testing or other purposes. To prevent false operation in this case, the relay sets
the receiving current data to zero in the differential current calculation upon detecting that the
remote terminal is out-of-service.
Figure 2.2.4.1 shows the remote terminal out-of-service detection logic. The local terminal can
detect that the remote terminal is out-of-service if it receives no interlink signal I.LINK-R1 from
the remote terminal. The interlink signal is configured from the circuit breaker CB and
disconnector DS status signal shown in Figure 2.2.4.2. Each terminal detects the out-of-service
condition and transmits its signal I.LINK to the other. Thus, out-of-service is detected when either
the circuit breaker or disconnector are open in all three phases.
The local terminal detects that the remote terminal is out-of-service by receiving a signal
L.TEST-R1 which is transmitted when the scheme switch [L. TEST] is set to "ON" at the terminal
under test.
I.LINK-R1
1651
1092 COM5-R1
By PLC
[OTD]
(+)
1104 SUB.COM1-R1
By PLC
LOCAL_TEST
R.DATA_ZERO
1587
Figure 2.2.3.2 Current Change Detection
1
&
" "
ON
L.TEST-R1
1650
Figure 2.2.4.1 Out-of-Service Detection Logic
⎯ 14 ⎯
I N
I s
I M
≥1
≥1
≥1
REM1_IN_SRV: Remote terminal in-service
REM1_OFF_SRV: Remote terminal out-of-service
6 F 2 S 0 8 2 8
432
REM1_IN_SRV
1
433
REM1_OFF_SRV
By PLC
2056 SUB.COM1-S1