VFD or Motor needs vitamins

regoss · Jul 28, 2007

I have an Automation Direct 1HP VFD which is about 3 months old driving the original motor on an M-Head.
This arrangement has roughly 20 hours on it and up until last week all was well. I went to use the mill and the RPM display on the VFD indicated 1095
instead of 1200, which were my Base and Max RPM settings. Decided to let it sit. A couple of days later when turned on the RPM had dropped to 838.
Today, 710. My question is, what's happening.
Motor or VFD?

viper · Jul 28, 2007

SHould be a VFD issue. You are probably running an open loop setup so the VFD will have no idea of actual motor RPM, just commanded RPM based on the frequency sent to the motor.

One thing you might do is get a cheap tach on the motor and verify the motor is turning its indicated speed on the VFD. That would at least indicate that the VFD knows it RPM and you have just have some settings that need changed.

Jraef · Jul 29, 2007

What are you using the change the speed command?

regoss · Aug 4, 2007

Sorry I wasn't clear on my original post. It wasn't that the VFD was indicating the the wrong speed, the spindle rpm was slower. Without going through all the machinations I tried --- I cut the power to the VFD off at the switch box and then switched it back on. It was "fixed". I have no idea, unless it was manufactured in the Twilight Zone.

Thanks for your responses.

Pierce Butler · Aug 5, 2007

Software bug. That happens. Be grateful that the software wasn't written by Microsoft. You would have to "reboot" it once a week.

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VFD or Motor needs vitamins

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