VFD question

GE/Fuji AF300-G11 drive with a 5K pot connected to terminals 11, 12, 13 of the drive. The only other control connection is a contact closure between FWD and CM to run the motor.

The problem is that when the pot is turned all the way down while the motor is running, the keypad unit shows an output frequency of around 15 Hz. Looking at the I/O monitor on the keypad shows 0 volts at terminal 12, although I didn't have a voltmeter with me to verify that. If I switch to keypad control of the output frequency, I can reduce the speed below 15 Hz.

Parameter F15 (High Limit) is 70 Hz, parameter F16 (low Limit) is zero, parameter F17 (Frequency Gain) is 100% and parameter F18 (Bias Frequency) is zero, all factory default settings.

Any ideas as to what else I should be looking at?

Many drives have an overall drive max and min parameter group and, in addition, max and min hz parameters specific to a particular input. That way the input can be scaled and offset independent of the overall drive limits.

Take a look thru your parameter list and see if there is anything that looks like max and min settings just for the speed pot input.

It sounds like your pot is not going to "0". Did you try disconnecting the wire on T12?

Reset to factory defaults and then re-parameterize it.

Dick, thanks for that. I don't see any parameters other than the four I cited that might affect the speed reference. The F parameters are supposedly the basic, general purpose setup. The "F" is supposed to mean "fundamental". Of course the manual is a typical case of being translated from Japanese to English by a person whose native language is Japanese.

Russ, I didn't disconnect the wire, and unfortunately I didn't have a meter available to measure the voltage, but the drive's keypad monitor told me that the voltage was zero.

Paul, in the absence of any specific parameters to check, that was going to be my strategy the next time I visit the facility. I plan to upload the current set into the keypad unit, set the parameter that restores to factory default levels, and then modify the ones I think are needed for the application.

Steve, do you have an instruction manual in electronic form that you can post here?

Dick, here's a link

http://www.hvacc.com/pdf/saftronics/GEI-100363.pdf

Steve, take a look at F18 and F23. It looks to me like either or both of these could force a minimum frequency onto the analog input value.

F18 and F23 were both at factory default values of zero and 0.5 Hz respectively.

As Russ suggested, first try disconnecting the pot. If that makes it go to zero, then the analog input may be picking up noise. If that's the case, you might want to try increasing the value of the 'Reference Filter' (C33). The default value is 0.05 sec., which should be adequate. Since you're just using a pot for speed control, you probably don't need a fast response to changes.



-Eric

I would record as many of the parameters as possible that are changed from default for your application and then do a default reset. Looking thru the parameter set on that drive, there are a number of other places where things could go wrong.

C31 - Analog input bias

I'm pretty sure I didn't see any parameters outside of the "F" series that nad been changed from factory default.

I haven't been back to the facility since my original post in this thread, so there is still no resolution to the problem.