PowerFlex 753 Short UV

n.costasilva

Member
Join Date
Jun 2017
Location
Michigan
Posts
6
Hello Colleagues,

I`m facing some problem with my new Powerflex 753, seems after sometime running, i try start the motor again and i have the message fault "short U/V", it happens with different motors i tried, the drive is not the problem, seems some parameter need to be changed or its to much sensitive.
I already have tried change the motors, and its running fine for sometime but later the fault back, it happens with different units also, I have 4 in the total, but just 2 have this small problem.
the motors and cables was tested many times, also it was replaced, but seems nothing really fix the problem.
Any ideas about this issue?
 
You say you tried it with different motors, but then you say the drive is not the problem. How do you know that? That fault means it is detecting high current flow between motor output terminals U (T1) and V (T2). It's going to be either the motor, a problem in the cables (see below), or a shorted transistor. If you have changed the motor and cables, but not the VFD, then it likely IS indeed the VFD. No parameter changes are going to fix this.

Was it brand new, or has it been working and this just began happening? Because if it is brand new, there is a small possibility that your cables are too long and/or too capacitive so the capacitive charging current of the cables is too high. But that only shows up at first, it doesn't really change over time. If it is a new installation and you want to test out that theory, you can "roll" the conductors. Move U to V, V to W, W to U. The phasing does not change, just the conductors do. If the fault changes to say "short V/W", then it's in the cable.
 
Last edited:
Hello Jraef,

the drives is brand new, to better understanding its a new installation and I have 5 Drives and 5 motors + 2 spares motors, seems when I change the motors by a new one it runs perfect, but after some hours it start have a problem, I already did the test you had suggested, and yes the faults move with the cable, but the strange is that I already replaced the cables and it is happening in the 3 of 5 modules.
I had switched the bad motor to a good drive, and the faults follow with the motor, all bring me to bad motor, but is not possible a new motor start be bad after some hours.
for make sure i tried a different type of motor and I have it running for some hours, and the same problem back.
maybe some parameter is wrong or too much sensitive.
I will let you know if we find out a solution for it.
 
Hello,

Thank you for your help, I'm using 50mt (1968.5 inches) cable, the drive is 750 series 250KW.
I will study the link you send me and see if we figure out the problem.

Thanks
 

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