14 STALL PROTECTION
Comprehensive features are available to protect the motor during the critical starting sequence. Measurements
and diagnostics ar
e also available to help you with the maintenance of the electrical process. For example, last
start time and last start current can be displayed on the HMI of the relay.
14.1 PROLONGED START
The following criteria can be used to detect a motor start.
Single criteria: a change in the interr
upting device position is detected. This is from open to closed or detection of a
starting current of more than the starting current threshold. The start criteria is set to 52a or I in the STALL
DETECTION menu settings.
Extended criteria: a change in the interrupting device position is detected, along with the detection of a starting
current of more than the starting current threshold, 52A+I. Both criteria have to be present within a 90 ms time
period.
Once a start has been detected, using one of these methods, and the current fails to fall below the current
threshold before the normal starting time threshold, a trip is initialized.
The diagram below shows detection of a successful start with the use of the extended criteria.
0
1
0
1
Start
Successful
Current
90 ms
Time
90 ms
Time
Time
Logic Input
CB Closed
0
Prol. Start Time
Starting
Current
P4968ENa
Figure 72: Start successful
An alarm (Pr
olonged Start) is generated if the current fails to fall below the starting current threshold before the
end of the starting timer.
Chapter 6 - Current Protection Functions P24xM
148 P24xM-TM-EN-2.1
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