# VFD not reaching 60hz



## MikeFL (Apr 16, 2016)

How long did that used one sit out of service?


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## Swanny (Jul 21, 2021)

MikeFL said:


> How long did that used one sit out of service?


I don't have any information on the replacement drive, but it looks like **** to be honest. A lot of fine dust on it.


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## micromind (Aug 11, 2007)

If the replacement VFD sat unpowered for more than a couple of years and the capacitors were not reformed, most likely they have failed and the inverter side cannot handle the excessive DC ripple. 

Often the caps will simply explode when powered up but sometimes they fail without any external indication.


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## Peewee0413 (Oct 18, 2012)

You might want to try and wire the fan to line voltage and check the current.


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## splatz (May 23, 2015)

Is it possible you have to do some scaling of the 4-20ma input in the drive's programming?


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## John Valdes (May 17, 2007)

Whats the max frequency set at? I would disconnect the motor leads at the drive and see if you can achieve 60 hz.
I have been out of the loop for a good while now, but in my day standard VFD will run without a motor connected. You may have the option to change a parameter to allow this as well. Just a thought.


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## gpop (May 14, 2018)

Vfd is trying to get to 60 but its either bumping the amp limit and backing off the hertz to allow it to recover or the caps are shot and the dc buss is dropping off causing the drive to back off to recover. 
If it was mine i would flash the program back to factory and start again especially if someone has already run a autotune on the drive.


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## Flyingsod (Jul 11, 2013)

All of what was said plus… remove the belt from the pulley and run it. If it works ok you prolly need to lengthen the ramp up. On big air handlers 2 mins is not inappropriate. 


Sent from my iPhone using Tapatalk


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## paulengr (Oct 8, 2017)

I don’t care how “good” your connections are. Do not assume that just because you are reading 20 mA that the drive does, too. This is mistake #1 especially with digital inputs. Always verify signals with what the drive sees.

Go into the monitor menu of the VFD and visually check the input signals and output signals and compare to what you measure. If there is something different it often indicates a problem.

Very likely though as others mentioned either the drive is detecting a mechanical or electrical overload or the programming is set too low somehow or the input signal as the drive sees it is low. So with the monitor menu you can narrow down your problem. 

Also before you even get that far with it off, grasp the motor shaft with your hand and try to turn it. A fan or pump should spin freely. If not, there is your problem. You can’t troubleshoot a mechanical problem electrically. Another test you should have done before connecting the motor is Megger it. Of course we know the motor looks good but if it was dropped hard enough in shipping that might not matter. And these are both things any motor tech knows and does on every motor install before spending time doing mechanical alignment and electrical connections. I’m sure your installers took a minute to do this?

I know this all sounds very basic but most issues are very basic most of the time. Once in a while I see something goofy. A customer last week had a drive indicating “ground fault” meaning a big current imbalance. Everything Meggered good. When they stopped trying to run at 60 Hz and measured at 10 Hz it was obvious. I tested coil inductance on it and it was very clear there were shorted turns in the windings, not ground fault. Motor was bad. That’s another test you can do, too.


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## JRaef (Mar 23, 2009)

gpop said:


> Vfd is trying to get to 60 but its either bumping the amp limit and backing off the hertz to allow it to recover or the caps are shot and the dc buss is dropping off causing the drive to back off to recover.
> If it was mine i would flash the program back to factory and start again especially if someone has already run a autotune on the drive.


I totally agree.

_*"...ended up buying a used powerflex 523 ..."*_

Used is the clue here, someone may have entered a low Current Limit setting and the VFD is just doing what it was programmed to do. Perform a full reset to factory defaults and start over. Go to Parameter P053, load a value of "2" and press Enter, it will flash and take everything back to the factory default settings, clearing out all weirdness.

I ALWAYS recommend doing that when starting with a used VFD, you can end up chasing your tail for days not knowing that the person before you had done something goofy.


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## sayedmhussein (11 mo ago)

What is the control method you are setting the drive, is it v/f or vector control, also when you get a stall error do the fan at that moment rotating or stuck? 

1. Make sure that all the mechanical parts are good like bearings and gears.
2. Check if the drive output power matches the system.
3. Check for some parameters of the drive related to the maximum frequency output.


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