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What are the possible causes of the SCF fault of a variable speed drive from the Altivar range?

An SCF fault is generated by the drive if a motor short-circuit fault (to ground or phase-to-phase) occurs.  Because of the nature and the destructive effects of this fault, this information is treated as a priority and is handled locally by the power bridge of the drive, which immediately disables activation of its IGBT power components.

This fault cannot be configured or reset; it can only be stored for indication purposes.

Diagnostics
The fault normally occurs in the motor or cables and can usually be found using a 1000V Megohm meter .
 
To do this, first remove the supply from the drive and allow time for the voltage to decay, then remove the motor cables from the drive and check them with the Megger. To earth this should be infinity.   The Phase to Phase value depends on the motor but the readings but it should be the same for all windings
 
On very rear occasions it could be a drive problem, to check this turn off the OPF and with the motor cables disconnected from the drive run the drive if you get the SCF fault appear it is a drive problem and you should contact Schneider Electric Technical support 

On the larger drives the ATV61 and ATV71 you can test the IBGT module by following the instruction in the programming manual, which can be down loaded from our web site
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