Testing Alarms in Danfoss VFDs

Hi-  Recently a customer asked about how to test alarms-- they wanted to commission the system and verify that VFD alarms are being seen at the front end.

We can use an open digital input, and program the vfd to think that there should be a jumper there-- typically used for a smoke detector or freezestat---no jumper means that the VFD would go into alarm.

Here is one way to do it:

1.       Verify Input 29 has no wires connected to it, if so pick another open input.  We used input 29 in this example because it is usually open in both bare drives and drives with bypass.

2.       Change parameter 5-13 “Digital Input 29” from [14] Jog* to [7] External Interlock.   *It might also be currently set for [0] no operation, that’s fine the point is that input 29 isn’t currently being used and has no wires connected to it.

3.       After you hit OK, the drive will immediately go into “Alarm 60, External Interlock”, and the motor will stop.  This alarm is usually used for external devices--smoke detectors or freezestats and would have to be jumpered to stop the alarm from happening.

4.       Verify that the alarm annuciates correctly at the front panel etc.

5.       Set parameter 5-13 setting to [0] no operation.  The VFD alarm should clear.  If it doesn't clear after a few seconds push the reset button on the VFD.  This just means that your parameter 14-20 Reset mode isn't set to automatically reset after the fault clears.

See Video Below