OT strange drive problem

I am having a strange problem with an installation I just did. I recently replaced some old 10HP DC drives with SSD 690 vector duty drives and Marathon Black Max TENV motors.

The application is an extrusion line for jacketing big (up to 1000MCM) undergroud cable. These motors drive belt caterpullers that pull the cable through the line. The cat closest to the takeup reel is run in tension mode and the the cat before the extruder is run in speed mode. Both drives have isolation transformers, both are setup in closed loop vector. I installed a DBR on the metering cat because I knew this was going to be somewhat of an overhauling situation.

Everything is running fine.

The problem is that the motor on the metering cat is getting really hot. I know the 5 second rule really isn't valid anymore but this motor is failing it. The drive is only displaying about 55% current and the torque demand is hovering right around 0, freq is about 50HZ. The DBR comes on occasionally but not for very long and it isn't generating any heat at all.

So my question is what could be causing this motor to get so hot when it really isn't doing that much work?

Calling DickDV..........

Have you done the motor-model tuning? ("Stationary Tune" usually).

55% doesn't seem out of range for Vector Mag Current, but it's possible the mag current is too high.

With the SSD it's a rotating tune and yes I did it and it seemed to tune fine.

A TENV motor is designed to run really hot. That's why the Black Max line is all Insulation Class H. Class H insulation is good for 40 degree C plus another 135 degree C rise totalling 175 degrees C.

That tells me you could cook on that motor! As long as the current and torque are within specs, I wouldn't worry about it.

The Marathon Black Max line is a most excellent motor and I doubt anything is wrong.

Black Max motors, being black the way they are, will drink heat like crazy. Is the motor being radiantly heated by the extruder?

Also, are the drive PWM frequencies set the same? Higher frequency PWM will produce a net increase in high frequency content (more pulses per second). All that content will get chewwed up as heat in the motor.

Keith

Thanks guys.

There isn't any radiant heat around the motor, it's about 70 degF and it's out in the wide open. The carrier frequency is whatever the default was, I didn't change it.

I checked the temp with a probe and it is about 67 degc between the fins. But I guess if it's good to 175 degC then I won't worry about it. It just seems odd because we have lots of these out there that are under fairly high load and they never seem to get anywhere near this hot.

allscott said:

With the SSD it's a rotating tune and yes I did it and it seemed to tune fine.

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You probably did but ill chuck it in anyways.......

Did you do the rotating autotune with the load disconnected ?

I normally do it 2 or three times as the figures seem to fine tune after the first autotune.

Class H is fry an egg job over here, and i have seen it done!!

I just came from an installation that had the same motor and it ran too hot to touch. It was driving a simple incline conveyor, so I wouldn't be too concerned. However, is this a C-face motor connected to a gearbox? If so, I have seen heat transferral from a poorly lubed gearbox to the motor attached. But, my gut is your installation is fine.

Robertmee, No this is a belted application so that's not the problem. 504Bloke, I've never thought of tuning more than once. Once it completes it once I've always just carried on, I don't even look at the numbers but now I will.

Edit: and yes there was no load when I tuned it.

allscott said:

504Bloke, I've never thought of tuning more than once. Once it completes it once I've always just carried on, I don't even look at the numbers but now I will.

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Remember to do a Paramter Save as well

You can also go online with CEDlite+ and see nice pretty colour meters of torque, current etc etc