Cumulative Start-Up Time Counter; 10.Circuit-Breaker Failure Protection - ABB REM 610 Technical Reference Manual

REM 610
4.1.4.9.
4.1.4.10.
34
Motor Protection Relay
Technical Reference Manual

Cumulative start-up time counter

The cumulative start-up time counter detects too frequent start-up attempts, which
cause overheating of the motor.
The start-up time of every motor start up is added to a register, Σt
register's value exceeds the set restart inhibit value, Σt
motor will be inhibited.
The time to the next possible motor start up depends on the countdown rate of the
start-up time counter, ∆Σt
For instance, if the motor manufacturer allows a maximum of three 60 s' motor start
ups in four hours, Σt should be set to 2 x 60 s + margin = 121 s and ∆Σt
si
s/4 h = 15 s/h; see the figure below.
åt s
[s]
150
Start 3
120
90
Start 2
Restart inhibit activated >St
60
30
Start 1
0
Fig. 4.1.4.9.-1 Cumulative start-up time counter operation
Note!
The register's value will decrease during motor start up as well.
Note!
If the emergency start has been activated, a motor start up will be allowed even
though the register's value exceeds the set restart inhibit value.
Circuit-breaker failure protection
The circuit-breaker failure protection (CBFP) detects situations where the circuit
breaker remains closed although the circuit breaker should have operated.
If a trip signal generated via output PO1 is still active and the current has not been
cut off on expiration of the CBFP set operate time, the CBFP will generate a trip
signal via output PO2.
/∆t, i.e. the rate at which the register's value decreases.
s
4 h
Next start possible
s
1MRS 752263-MUM
. When the
s
, any attempt to restart the
si
/∆t to 60
s
(121 s)
i
CumCount_a
t