1336 impact drive

[mikie2243]

I would guess from your description that changing out motors is not a trivial task. There are things that you can do though. Check the axle driven by the problem motor for mechanical issues. Bad bearings, (Dragging Brakes?) bad gearboxes if fitted etc. If you don't have a spare 1336 VFD, try swapping two of them, and see if the problem stays on the same axle, or moves with the VFD. Bring in your nearest motor shop with better test equipment, and have them do a test of the motor. If the motor can be uncoupled easily from the axle, uncouple it, and spin the motor looking for mechanical problems like bad bearings etc. The shaft should spin freely without any tight spots or bad noises.

You only really have 3 choices, either there is a mechanical problem with the axle causing the overload condition, there is a problem with the motor, or there is a problem with the VFD, which could also include its power and motor wiring, inline inductors etc. For instance, a bad connection on one of the phases to the motor could cause higher current on the remaining two phases.

Since you describe it as a motor overload, in my experience that is almost always a problem in the connected load. The next most common problem is the motor, wiring issues surrounding the VFD, and very rarely, a problem with the VFD (failed internal component etc).

Others may have had different experiences, but that has been my experience working on well over a thousand Motor Systems, and hundreds of VFD/Motor systems.

Stu.....

Thanks for the input, I'll have them jack up the tires and spin them tonight. Its a 15 hr operation to get the axle and motor out and back in.

 

[OZEE]

We have used drive observer to compare all 4 drives and the parameters on all 4 are the same.

There's not a single one of us here who is concerned about the parameters - unless the parameters are wrong across all four drives, which none of us are concerned about. The VFD is generating that fault to protect itself. To put it bluntly - forget about the parameters!! They're not the problem...

The only thing you see when it fails is a spike in current.

THERE'S A CLUE!! That's what's causing the fault! That's EXACTLY what that fault is designed to detect!! The drive is doing its job!

NOW - what's causing the spike in the current? Is it a spike on one phase or on all three phases? How high of a spike? One way to think of it: The current spike itself is not the problem -- it is the SYMPTOM of the problem. What sorts of things would cause a current spike? Most of them are mechanical: a problem with the load or a physical problem with the motor itself.

If it were me, I'd be trying to schedule that 15 hours of downtime before it schedules itself for you...

 

[JeffKiper]

Look for mechanical issues. I am not saying that it is not a drive or motor. I like several others would use this as a troubleshooting tool. Think of this as a fever. If you don't pay attention to it you may land in the Hospital.
Don't put to much faith in the guy before you. We have all seen PLC, HMI, & various other components that have been setup wrong. I did a small job with some signal conditioners. It was a replacement so no big deal just copy and paste the numbers. The guy before me did scaling in the signal conditioner and PLC. The signal was getting rounded in 2 places. I just did it in the PLC. My numbers where a little bit closer. I am sure there are guys that have followed something I did and said why would you do it like that or have seen where I tweeked a number to make the process run.

Double check the numbers in the drive like others have said they could be wrong. Have these motors ever bee changed? Make surethat motor and drive par. are the same.

I think I saw where you used drive explorer to compare parameters. Do a complete compare and see if the ALL of the numbers are the same. Make sure somebody didn't copy and paste all of the motor parameters. Each motor will have it's own special numbers for after an autotune.

 

[DickDV]

Noting your comment about seeing a current spike, a motor overload fault, if properly set up, will not respond to a short current spike. "Motor Overload" takes the motor current and integrates it over a period of time to estimate heat accumulation in the motor. Response to a short spike, if high enough, is intended for "Drive Overcurrent" or "Short Circuit" fault.

Noting OZEE's comments, there are those of us that are concerned about how the parameters are set up, even tho the four drives are set up identical. All four could be set up wrong. The observation that a "spike" causes a motor overload fault tells me that the time curve in the drive software may well be set too short. As the trams gain operating hours, the motors and machinery wear differently so you no longer have identical motors and loads. The one that is tripping may just be the first sign that the programming is not optimal. With a traction motor on a tram, I would think that the overload time curve would be minutes, not seconds. If the current spike rises so high that the fault is nearly instantaneous, then a flash in the motor is a strong possibility.

Please understand that I am not proposing that the drive programming is the most likely cause. Certainly, mechanical and motor electrical issues are. But, don't rule out the drive setup. Your tram just might be wearing normally and the changes are starting to cause nuisance faulting.