Flexpak 3000 DC drive

Hello everyone,

We have a problem on one of our Flexpak DC drives. It was newly installed but when we commissioned it, an IET overcurrent fault occurred. We checked everything as stated in the manual and noted that all parameters & jumpers are correct.

We swapped the DC motor from the other machine, but the same problem occurred in this Flexpak drive. We even replaced the motor armature cables but the fault still occurred. The motor would just turn for a few seconds then the fault would occur.

We tried the Armature Phase Fire test, first, with the motor armature leads still connected (we locked the motor armature and disconnected the field supply as stated in the manual). But we could not proceed with the armature phase fire test because the same IET overcurrent fault would occur. Then we disconnected the motor armature leads and replaced it with a dummy load (bulbs in series). This time no fault occurred and we were able to proceed with the phase fire test. We noted through the oscilloscope that the SCRs are operating well since there were no missing "bumps" in the waveform generated. When we repeated the armature phase fire test with the motor armature leads connected, it won't proceed with the test again since the IET overcurrent fault would occur.

We had also tried swapping the boards, i.e., the Regulator board, the power supply board, the FCR, and even the Power Interface board. But it did not solve the problem either. On the other hand, the boards from this drive worked well in the other machines.

Please also note that there were no fuses blown in the AC nor in the DC line.

We are now contemplating on checking the SCRs again and test it individually.

We really are wondering what could be the problem with this Flexpak 3000 DC drive. We have e-mailed Rockwell but unfortunately, until now there was no reply. Hope you guys could help us in any way possible.

Thanks. Godbless.


Mafe

You seem to have been quite thorough in your testing but, without meaning any offense I have to ask the obvious. Have you done the current loop and field loop tuning properly?

These determine how the drive electronics manage the armature and field and are basic to any commissioning process.

Can you repeat for us what the drive Instruction Manual says concerning the fault you are having.

you getting a high mechinical load through a short period of time , what you need to do is to increase the acceleration time , first try that, then , second , reduce the armature voltage and limit it to a lower value,
you don't have any problem with the drive , nor with the machine , it is just wrong set up, for me same if you start you car and your gad pedal is all the way to the floor.