# Altivar drive wont start motor



## varmit

These VFDs are not normally repairable. If the drive is 10 years old, it has lasted longer than average. Time to replace.


----------



## Cow

I've only messed with altivars enough to know I don't like how they program or their menu structure. So I'll just give you some basic troubleshooting advice based on what I'd try.

I'd hook up a different temporary motor(a known good one of course), any size you have laying around and see if it'll run that. I've been known to string THHN right across the ground from one MCC bucket to another for testing purposes, if that's what it takes.

If it still won't start it, I'd reset the drive back to factory defaults and then reprogram it back to what it was. If it still didn't run the temporary motor, I'd replace the drive.


----------



## frenchelectrican

farlsincharge said:


> 208 3 phase motor running centrifugal pump on water distribution system. Approx 10 years old. Operator says he came in one morning and the motor wouldn't run.
> Altivar drive with very slow ramp time. Ramps up to 5 hz and just sits there. If I give the motor a kick by hand it takes off, and everything is normal.
> 
> The motor checks out, its definitely a drive issue.
> Just looking for some ideas on where to start.
> Feedback parameters in the drive? I have played with altivars a little bit, but nothing too advanced.


Cow did bring up few good pointers on the basic grist of troubleshooting it.,

I been wondering if you change the ramp up time window to more tighter ? if you allready know what it is set up on the exsting VSD ? ( I would make a note of the setting before you tweak it further or reboot back to factory default.) 

I am leaning toward to bad VSD unit .,, You did not mention how big this motor it is ., if that is a small one ( less than 5 HP ) I would get a new VSD drive.

Most centrifugal pump useally are pretty fast ramp up on ramp up time unless a specfic reason then it will be slower ramp up time.


----------



## WiredCanadian

No faults showing on the drive? Is it perfectly happy struggling at 5hz?


----------



## varmit

Probably input side caps have died. Can you access the parameter to read the DC buss voltage? I don't have my manual handy.

Again, what size drive / motor is this?

Other items/ parameters to check:

commanded frequency ( the speed the drive thinks it's speed reference is)
output torque percent ( the amount of load on the VFD)
VFD output amps (on display, not with clamp on meter)

Check all three incoming phases for voltage and current.

Take ALL motor leads apart, at motor, and take an ohm reading on all 6 windings.


----------



## varmit

If you have a meter with an accurate diode test function, you could check the power sections of the VFD.

FIRST, POWER DOWN THE VFD AND DISCONNECT THE MOTOR FROM THE VFD.

Check from each line terminal to the DC buss terminal, then swap meter leads positions and test with the other polarity. Do the same test on the VFD output (T lead) terminals to the DC buss. On one polarity the reading, depending on brand and model, will be about .200 to .600. The opposite polarity should read 0. the actual values are not as important as your want them to be very close to the same reading in the same polarity.

I hope that this makes sense.


----------



## JRaef

farlsincharge said:


> ... If I give the motor a kick by hand it takes off, and everything is normal...


This part concerns me a lot. Can you explain exactly how you are giving the motor a kick by hand?

The only thing I can think of is that you have a broken rotor bar inside, and that is interrupting the rotor current flow when the drive is trying to start, so it is not creating torque or reacting with the stator correctly, the stator current is high but with no torque, so the VFD is going into Current Limit and not allowing the frequency to increase. Once you spin it, the bad rotor bar becomes less relevant.

VFDs are exceptionally good at finding motor internal defects that you can't easily see with simple tools. A broken rotor bar doesn't show up at all with any tests you can do on a stator.


----------



## paulengr

I’ve seen VFDs do this when single phasing / current imbalance tripping is turned off. So no torque at max current. Also could be a blown transistor. The diode test will test the anti parallel diodes but not the transistors. Those are best seen with a scopemeter.


Sent from my iPhone using Tapatalk


----------



## paulengr

JRaef said:


> This part concerns me a lot. Can you explain exactly how you are giving the motor a kick by hand?
> 
> The only thing I can think of is that you have a broken rotor bar inside, and that is interrupting the rotor current flow when the drive is trying to start, so it is not creating torque or reacting with the stator correctly, the stator current is high but with no torque, so the VFD is going into Current Limit and not allowing the frequency to increase. Once you spin it, the bad rotor bar becomes less relevant.
> 
> VFDs are exceptionally good at finding motor internal defects that you can't easily see with simple tools. A broken rotor bar doesn't show up at all with any tests you can do on a stator.


I can find them. It's called a rotor influence check. Time consuming compared to online testing but works like a charm. You basically measure inductance of the rotor every few degrees and chart it. I wouldn't ever do it by hand though (without a pdma).

Sent from my SM-T350 using Tapatalk


----------



## AK_sparky

paulengr said:


> I can find them. It's called a rotor influence check. *Time consuming* compared to online testing but works like a charm. You basically measure inductance of the rotor every few degrees and chart it.* I wouldn't ever do it by hand though (without a pdma)*.





JRaef said:


> VFDs are exceptionally good at finding motor internal defects that *you can't easily see with simple tools*. A broken rotor bar doesn't show up at all with any tests you can do on a stator.


I don't think "time consuming" and "wouldn't ever do it by hand" fall under the aforementioned "easily...with simple tools".


----------



## paulengr

AK_sparky said:


> I don't think "time consuming" and "wouldn't ever do it by hand" fall under the aforementioned "easily...with simple tools".


OK, how about wrenches and just take the end bells off and look? Fine under about 25 HP. Not so easy as the motor gets really large, On little ones actually tearing one down takes only a couple minutes.

Sent from my SM-T350 using Tapatalk


----------



## frenchelectrican

paulengr said:


> OK, how about wrenches and just take the end bells off and look? Fine under about 25 HP. Not so easy as the motor gets really large, On little ones actually tearing one down takes only a couple minutes.
> 
> Sent from my SM-T350 using Tapatalk


I just have one 15 HP motor that have broken rotor bar and it was making soft knocking noise and I knew what that sound came from and I pull the motor apart and behold it was broken rotor bar and end up replace the motor.


----------



## John Valdes

He says it runs after he kicks the motor. How could the drive be at fault. He's not kicking the drive. He's kicking the motor.

I'm with Cow. Get another small motor, hook it up and see if it runs on the drive. Or if its just a standard Volts/Hz drive, run the control without a motor.

I like to keep things simple, until they become not simple anymore.


----------



## JRaef

I used to have what was called a "growler" we used for checking rotors. They are made for DC armatures, but they work on AC rotors, just a little differently because there are no windings. It was essentially half of a stator frame with a V shaped crotch in which you rested the rotor. With the DC armatures you would rest it in the crotch and energize the stator to induce current flow in the armature windings. they you would put an old hacksaw blade on it and wherever there was an open armature winding, the blade would vibrate, or "growl". You can see them in action on Youtube. On an AC rotor when you energized that half-stator, it induced the current flow in almost all of the the rotor bars at the same time so the hacksaw blade thing was less obvious. So we would place a piece of white paper around the rotor and sprinkle iron filings over it. The iron filings would clump around the magnetic fields of the rotor bars, so any bar that wasn't conducting would show up as a gap on that paper. I lost that in my business sale long ago, it was too big and heavy to haul away. Too bad...


----------

