VLT 5000 Danfoss inverter

[choota]

hi guyz. i have a problem with my vlt 5000 danfoss inverter. whenever i start the motor it brings the "overcurrent alarm" while the current is well below the nominal value (at 18A while the nominal current is 38.4Amps). i ve tried to replace the card but that didnt help as well. would you please help me anyone.

Thanks in advance!

 

[DickDV]

The overcurrent fault is very fast, in the range of milliseconds. You may have a starting inrush condition that doesn't last long enough for the display to capture it.

I would first check to see if the starting voltage boost is set too high. Set it down to zero and see if you get the fault. If it goes away, slowly increase it until you either get enough starting torque for the application or the fault comes back. Setting it just below the fault level is about the best you can do.

I am assuming the drive is in V/Hz mode, not sensorless or flux vector.

 

[nightex]

As you already know overcurent function measures curent transformator current and compares it to nominal curent set in certain parameter. So there is three posibilities one of them is mechanical problem as DickDV states, other is incorectly set current or voltage or other motor parameters, faulty current measuring system of drive or induction of other electromagnetic fields, or maybe there is problem with motor windings isolation which may result of decreased winding resistance which is automaticly result of high curent. So there is 4 possibilities as I see it.

 

[Michal_dk]

The VLT5000 is not one I'm familiar with, but did you try to initialize the VLT?
Par. 1-07 is the automatic motor adaptation (AMA on the FC series VLT).
Par. 6-20 is the initialize mode.

Both parameters will reset the current transformers in an FC302, I'm guessing they will do the same on a VLT5000.

Best regards,

Michal