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Parameter
Number of Starts:
Number of Warm Starts (Nws):
Temperature of Warm Start (Tws):
Reset Time (t rst):
14.7.3.4.1 Operation criteria
If the Thermal Overload protection is not enabled the estimated machine temperature is not available
and the Warm counter is not increased (the Warm counter is frozen on zero). In this case, all
counted starts are classified as cold.
When the Thermal Overload protection is enabled the estimated motor temperature is compared
with the setting temperature threshold (Temperature of Warm Start Tws). Above Tws temperature
threshold a start is assumed to be "warm", below this it is assumed to be a cold start.
With every motor start, depending on the type of start (i.e. warm or cold start), the relative counter
is incremented by one unit. With every warm start, both the warm counter and the cold counter
are incremented.
If no start has occurred after the set time interval (Reset Time, t rst) it is assumed that the motor
had time to cool down and both cold and warm start counters are decremented by one unit.
If the preset number of warm (Number of Warm Starts, Nws) or respectively of cold starts (Number
of Starts, Ncs) is reached, then the protection function is started and the relative Start signal will
be activated. If there is another start, the protection function will enter the TRIP status and the trip
signal will be activated.
The protection function is in trip status and the trip signal remains active until the reset period t rst
has expired; then both cold and warm start counters are decremented and the trip signal is cleared.
The protection function will exit start status, return to passive status and the start signal will be
cleared if the cold and warm counters fall below the respective maximum setting values Ncs and
Nws, i.e. after the reset period t rst has expired.
Values
Default
Step
1 ... 10
10
1
1 ... 10
10
1
20 .... 200
100
1
1 ... 7200
30
1
Unit
Explanation
-
Number of starts above Tws.
-
Number of starts below Tws.
°C
Temperature threshold
to define a warm start.
s
Time to cool down
after a start.
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