# Danfoss VLT 2800, Error code 16



## Cow (Jan 16, 2008)

Have you visually inspected the conduit/wiring to the motor as well as opened up the motors j-box to take a look?


I've had wiring vibrating and every once in a while a spot that had been rubbed through from a poorly done termination would make contact with the motor j-box.


I've also had an AB drive once give me a ground fault on 30HP motor. Everything megged perfect. But it wouldn't run the motor without throwing a ground fault, I believe it was. Turned out the motor was bad and only the highly sensitive drive electronics could pick it up, not a megger. In 10 years of megging, I think I've only seen this once though.


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## JRaef (Mar 23, 2009)

Yes, VFDs are often better at "fault finding" than most test instruments, mainly because they are on-line all the time, not just when you connect the meter.


Intermittent SC faults are, as Cow says, often associated with movement / vibration, which is something you cant simulate when connected to a meter. The other thing I have encountered is moisture in the conduit, especially from condensation, because it takes specific conditions to replicate it and those conditions are inconsistent. It also is something that can take place as a result of long term degradation of the conductor insulation if they used THHN. You can get Partial Discharge (PD) faults where there is a phase-to-phase burn through between conductors. That will not show up on a basic megger test to ground because the leak is not to ground. What fits about that is that most VFDs differentiate between SC and GF faults.


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