VFD Malfunction
VFD Malfunction
(OP)
I was recently called to look at a problem at a well pump facility. Installed is an Eaton SVX9000, a TCI KMG Sine Wave Filter, 4400 feet of motor wire in buried PVC conduit and a 20 HP submersible well pump. The system has operated since 2008 without any problems. Four weeks ago it was found that the pump/VFD would not operate above about 48 hertz. That is, the drive could/would not operate at full speed either on remote or local (potentiometer). I verified that the remote input was 100%. I removed the load wiring from the VFD and operated it at 60 HZ both in remote and local. The current settings look OK, with no current limiting of speed. There is an identical unit, working, less the sine wave filter, about three feet away, with about 150 feet of motor supply wiring. I took the operator interface from that unit, inserted it into the malfunctioning VFD and downloaded the settings from the working unit with no luck. Anyone have any reason for the drive logic to limit the hertz output?
Thanks
Steve
Thanks
Steve





RE: VFD Malfunction
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RE: VFD Malfunction
Emphasis added.
"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> FAQ731-376: Eng-Tips.com Forum Policies
RE: VFD Malfunction
RE: VFD Malfunction
If this is on a pump and has been working fine for a long time but suddenly changes, it could be an indicator of a flow problem because flow = load in a pump. So if for example you have a pipe break or a severe leak, your flow is increasing and thus the load on the motor. The drive is responding to the added load by reducing the commanded speed. Up to 48Hz the motor load is within the drive's parameters, but above that it is overloading and if you have that feature enabled, the response is to drive the speed down artificially.
"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> FAQ731-376: Eng-Tips.com Forum Policies
RE: VFD Malfunction
Keith Cress
kcress - http://www.flaminsystems.com
RE: VFD Malfunction
RE: VFD Malfunction
Thanks All
Steve