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software is running normally.
DC Supply Monitoring
The secondary voltage level of the built-in DC/DC converter is monitored, and is checked to see
that the DC voltage is within a prescribed range.
The alarms are issued when the failure continues for a predetermined time. The times for each
monitoring item are as follows;
• A/D accuracy checking, memory monitoring, Watch Dog Timer, DC supply monitoring:
less than 1s
• AC input imbalance monitoring, sampling synchronization monitoring : 15s
3.3.3
Trip Circuit Supervision
The circuit breaker tripping control circuit can be monitored by a binary input. Figure 3.3.3.1
shows a typical scheme. A binary input BIn is assigned to No.1548:TCSV signal by PLC. When
the trip circuit is complete, a small current flows through the binary input and the trip circuit. Then
logic signal of the binary input circuit BIn is "1".
If the trip supply is lost or if a connection becomes an open circuit, then the binary input resets and
the BIn output is "0". A trip circuit fail alarm T_FAIL is output when the BIn output is "0".
If the trip circuit failure is detected, then "ALARM" LED is lit and "Err: TC" is displayed in LCD
message.
The monitoring is enabled by setting the scheme switch [TCSPEN] to "ON" or "OPT-ON". When
"OPT-ON" is selected, the monitoring is enabled only while CB is closed.
(+)
Trip
output
CB trip coil
3.3.4
Differential Current (Id) Monitoring
The DIFSV element is provided to detect any erroneous differential current appearing as a result
of CT circuit failure. The tripping output signal of the DIF elements can be blocked when the
DIFSV element output is maintained for the setting time of TIDSV. To block the tripping output
with DIFSV operation, set scheme switch [ IDSVEN ] to "ALM&BLK". To alarm only, set to
"ALM".
3.3.5
Telecommunication Channel Monitoring
The telecommunication channel is monitored at each terminal by employing a cyclic redundancy
check of the received data. The check is carried out for every sample.
If a communication failure is detected continuously for ten seconds at a terminal, a communication
failure alarm "Com fail" is issued at the terminal.
BIn
By PLC
BIn command
1548
CB CLOSE
"OPT-ON"
[TCSPEN]
+
Figure 3.3.3.1 Trip Circuit Supervision Scheme Logic
Trip circuit supervision
TCSV
1
≥1
&
"ON"
⎯
⎯
61
6 F 2 S 0 8 2 8
t
0
1359
TC_FAIL
&
0.4s
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