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What can cause an SCF1 fault on an ATV320?

Published date: 02 August 2019

Issue:
What can cause an SCF1 fault on an ATV320?

Product Line:
Altivar 320

Environment:
All

Cause:
Motor short circuit

Resolution:
Except real short circuit at ATV output (motor, motor cables) SCF1 can have another reason:
It can be due to high magnetizing current (motor saturated), low motor inductance (real vs measured), unsymetry in motor ciurcuit, problem in motor cabling, or the motor itself.
The best way is to record scope (fast scope) with LCR, SLCR, RFR to see the moment when SCF1 occurs. Autotuning data can affect occurence of SCF1.
Try to lower LFA a little and record the same somove scope again (fast scope, sampling time 10 ms or faster if it reveals anomalies) . Compare the results at different LFA. IT is recommended to apply same load cycle to find comparison relevent.
Also Check if magnetizing current IDA measured by the ATV correposnds to reasonable value. (In * sqrt (1-(cos phi)^2)
Try different motor control law.
Change switching frequency, sometimes it helps when increaeing Sfr, sometimes when decreasing.
Think about adding motor choke as this choke can reduce riplpes in motor current and so higher probablity that SCF1 threshold will not be exceeded.

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