Powerflex 4m

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jomamma1

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Modesto, California, USA
Background: I am replacing an obsolete Allen Bradley 160 VFD with a PowerFlex 4M. Older 160 used a dynamic braking resistor. When we powered up the PFlex, the dynamic braking resistor burned immediately. I have ordered a new resistor for the new drive, but before I power it up again I want to make sure that all setting are correct. Have any of you had this problem? Any advice?
Thanks,
Joe in Modesto
 
Odd that it would energize the resistor at all on power up as there can't be excess voltage on the DC bus.

I would be inclined to reset the drive to its default parameters and then set whatever parameters need setting.
 
ptonsparky said:
Looking at the terminal locations on the VFD, it would appear to be an OS moment by the installer. The OS moments, I have experience with. Braking resistors, I do not.
Click to expand...

After I got my BS degree, I entered the workforce and got my OS degree...

I'll bet I know exactly what the OS moment was on this one. The PF4M in the sizes below 7-1/2HP at either voltage do not have internal Dynamic Braking transistors. If you connected the resistor to DC+ and DC-, you connected directly to the DC bus in the drive. Hopefully you didn't damage the drive. Probably not though, the resistor would have acted like a current limiter until it became a fuse, and hopefully the current limitation was below the damage curve of the diode bridge.

If you need the braking, you need to change to the PF523. It has a mounting accessory that adapts the 523 for feed through wiring like the 160 had. Then double check your resistor values befor using it.
 
Jraef said:
I'll bet I know exactly what the OS moment was on this one. The PF4M in the sizes below 7-1/2HP at either voltage do not have internal Dynamic Braking transistors. If you connected the resistor to DC+ and DC-, you connected directly to the DC bus in the drive. Hopefully you didn't damage the drive. Probably not though, the resistor would have acted like a current limiter until it became a fuse, and hopefully the current limitation was below the damage curve of the diode bridge.
Click to expand...

That would do it. I never even considered someone would do that.
 
Where in the heck is our LIKE button???

Where in the heck is our LIKE button???

ptonsparky said:
Looking at the terminal locations on the VFD, it would appear to be an OS moment by the installer. The OS moments, I have experience with. Braking resistors, I do not.
Click to expand...

Not only the likely reason, but so eloquently stated!!

Thank you for making my day!
 
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