Failure Alarms; Circuit Breaker Condition Monitoring; Binary Input Setting For Cb Condition Monitoring - Toshiba GRE110 Instruction Manual

Circuit Breaker Condition Monitoring

Periodic maintenance of the CB is required for checking the health of the trip circuit, the operation
mechanism and the interrupting capability. Generally, maintenance is based on a time interval or a
number of fault current interruptions.
The following CB condition monitoring functions are provided to assist in determining the
appropriate time for maintenance of the CB:
• The number of trips is counted for maintenance of the trip circuit and CB operation mechanism.
The trip counter increments the number of tripping operations performed. An alarm is issued
and informs the user that maintenance is due when the count exceeds a user-defined setting
TCALM.
The trip count alarm can be enabled or disabled by setting the scheme switch [TCAEN].
• Sum of the broken current quantity ∑I
CB. The ∑I
y
counter increments the value of current to the power 'y', recorded at the time of
issue of the tripping signal, on a phase by phase basis. For oil circuit breakers, the dielectric
withstand of the oil generally decreases as a function of ∑I
changes, etc., may be required. 'I' is the fault current broken by CB. 't' is the arcing time within
the interrupter tank and it cannot be determined accurately. Therefore, 'y' is normally set to 2 to
monitor the broken current squared. For other circuit breaker types, especially those for HV
systems, 'y' may be set lower, typically 1.0. An alarm is issued when the count for any phase
exceeds a user-defined setting ∑I
setting the scheme switch [∑I
• Operating time monitoring is provided for CB mechanism maintenance. It checks CB operating
time and the need for mechanism maintenance is informed if the CB operation is slow. The
operating time monitor records the time between issuing the tripping signal and the phase
currents falling to zero. An alarm is issued when the operating time for any phase exceeds a
user-defined setting OPTALM. The operating time is set in relation to the specified interrupting
time of the CB. The operating time alarm can be enabled or disabled by setting the scheme
switch [OPTAEN].
The maintenance program should comply with the switchgear manufacturer's instructions.
The CB condition monitoring functions are triggered each time a trip is issued, and they can also be
triggered by an external device via binary input EXT TRIP3PH (EXT3PH) or EXT TRIP∗PH
(EXT∗PH) as shown in Figure 3.3.4. (Refer to Section 4.2.6.8.)
(+)
(−)
Figure 3.3.4

3.3.5 Failure Alarms

When a failure is detected by the automatic supervision, it is followed with an LCD message, LED
indication, external alarm and event recording. Table 3.3.1 summarizes the supervision items and
alarms.
y
is counted for monitoring the interrupting capability of
ALM. The ∑I
y
y
AEN].
External trip
GRE110
three-phase
BIa
External trip
A-phase
BIb

Binary Input Setting for CB Condition Monitoring

 73 
2
t, and maintenance such as oil
y
count alarm can be enabled or disabled by
Binary input setting
[EXT3PH]
BIa command
"ON"
[EXTAPH]
BIb command
"ON"
6 F 2 T 0 1 7 2
EXT3PH
EXTAPH