Baldor 12 wire motor

[leitmotif]

What about Motors that are 480 and have a 120HZ or 90 HZ rating on the nameplate?

Do you lose torque when you run those at 120HZ?

My bakery has 2 100 HP motors like that.

Tim

I think you will find the motor rated for a baseline of 60 Hz. You can verify this by RPM rating and poles. The 90 or 120 Hz rating indicates (I believe) the motor is built for VFD duty and is designed / rated to go above baseline.

Send photo of a motor nameplate to confirm my thoughts please.

Dan Bentler

 

[allscott]

I believe you are correct Dan, I have seen these nameplates before as well and that is my interpretation.

 

[DickDV]

You have to determine from the nameplate what the base frequency is. Typically, it will be 60hz which is the point where the voltage reaches the nameplate value, typically 460V. The available torque will be constant from zero to 60hz.

From 60hz up to 120hz, the voltage cannot rise any further so the torque starts to drop off at rate equal to the inverse of the overspeed.

If the motor nameplate has data for 120hz, that is a sign that it is rated for constant horsepower from 60 to 120hz (decreasing torque) and that it is safe to operate at those speeds.

There is a small possibility that you have a very special motor that has a 460V rating and a 120hz base speed. That motor will develop constant torque from zero to 120hz but it will be only half of that of the 60hz motor from 0 to 60hz.

 

[briancr]

OK guys, we are deviating a bit from my initial problem, although some very good points are coming out of this thread.

Here is my setup. It is an American built machine, so our voltages are different, we use 380V three phase here. Two 11Kw motors connected to one 22Kw drive. Nothing spectacular about the setup, it has a jog speed and a run speed. The operator has access to a speed control pot, product A runs at X speed, product B runs at Y speed etc, he sets the speed by a rpm meter, speed control is not critical, 10rpm either way is no train smash. This machine was built for our European sister company, but relocated to us.

My problem is this, the blown drive is rated at 230V three phase and the motors are wired for 230V three phase. The way we were running before is having a 380V / 230V three phase transformer to give us the required voltage. Yes it is a fairly large transformer. This drive is the only one rated at that voltage we have in our entire plant, hence my desire to change it to our standard make of drives we use, only 380V three phase drives. I could change the motors as I said previously, but if I don't have to would be a bonus and wire them for 460V, use a 380V drive, and then tweak max frequency to negate the speed loss obtained to get my required rpm out of the machine. I have no need to go above 50Hz to the motors

Our supply is 50Hz and the motors are rated 60Hz

I hope this makes better sense of my situation

Once again, thanks guys for the input, some very interesting thoughts and views

 

[jrwb4gbm]

Go ahead and wire the motors for 460 volts. Install a drive rated for 380 volts input. Adjust the Volts per Hertz if necessary so that the VFD is set for 380 volts at 50 Hertz.

 

[Tom@Pton]

Does this work as well for a 240v 3ph that I want to run at 120hz? 2hz/volt? I think I am missing something here because I can't wire this motor at the peckerhead for 120v.

 

[allscott]

OK guys, we are deviating a bit from my initial problem, although some very good points are coming out of this thread.

Here is my setup. It is an American built machine, so our voltages are different, we use 380V three phase here. Two 11Kw motors connected to one 22Kw drive. Nothing spectacular about the setup, it has a jog speed and a run speed. The operator has access to a speed control pot, product A runs at X speed, product B runs at Y speed etc, he sets the speed by a rpm meter, speed control is not critical, 10rpm either way is no train smash. This machine was built for our European sister company, but relocated to us.

My problem is this, the blown drive is rated at 230V three phase and the motors are wired for 230V three phase. The way we were running before is having a 380V / 230V three phase transformer to give us the required voltage. Yes it is a fairly large transformer. This drive is the only one rated at that voltage we have in our entire plant, hence my desire to change it to our standard make of drives we use, only 380V three phase drives. I could change the motors as I said previously, but if I don't have to would be a bonus and wire them for 460V, use a 380V drive, and then tweak max frequency to negate the speed loss obtained to get my required rpm out of the machine. I have no need to go above 50Hz to the motors

Our supply is 50Hz and the motors are rated 60Hz

I hope this makes better sense of my situation

Once again, thanks guys for the input, some very interesting thoughts and views

Are you sure the drive is only rated for 230V? That is the key here, I would suspect the drive is actually rated for 480V and the motor wired for 230V.

 

[briancr]

@ Allscott. Yes definitely 230v three phase, see attached picture of drive rating. I did mention in my last post that we are using a 380 / 230 V transformer

I have been doing some googling, doesnt look like that size drive is made anymore. Now my problem compounds, we have a few more motors (DOL) on the machine, also wired 220V three phase.

Its now up to management to decide, its either a complete retrofit or scrap the machine. I would hazard a guess a retrofit will happen, these machines cost approx. R15 million, thats $2 million.

This is what happens when production guys get involved in purchasing of equipment and dont involve the engineering guys. What used to be a pet peeve of mine, production guys purchase new machinery, dont care what type of control systems are installed, I have to live with whatever gets delivered. Luckily I have managed to get them to see the light on that one, I now get involved in the purchasing

 

[DickDV]

Briancr, I would caution you that some of the advice you are getting in this thread is bogus, at best.

Let's start with the basics: available motor torque is a function of the V/hz ratio.

The motors you have are 60hz base speed and are dual wound for 230VAC and 460VAC. This means that the insulation is good to at least 460V.

Your supply is 380V 50hz and you want to run the drive and motor at this voltage and frequency.

You want to preserve the torque producing capacity of the motor which, in effect means that the V/Hz ratio must be preserved.

OK, with those principles in mind, why not keep the existing motors, keep them connected for 230VAC 60hz (3.83V/Hz), buy a 380V drive with the ampacity needed for the motor connected for 230V 60hz, and set the drive up with the motor data being entered into the drive modified to 380V and 99Hz. That's still a V/hz ratio of 3.83 and the voltage is also under the 460V capability of the insulation. This would give you a motor with the same available torque from zero up to 99hz. You don't want that much speed? OK, set the speed or frequency limit on the drive to 50hz.

You've just created a 380V 50hz system with the 230V 60hz drive.

Now, what did I leave out?

 

[briancr]

Now, what did I leave out?

A beer for the master

Thanks DickDV, your advise is always of the best, its no wonder people listen to you

 

[brandoncosta]

Baldor's 50Hz motors

http://www.ctiautomation.net/Baldor-50Hz-Motors.htm

 

[Thomas Sullens]

Briancr, I would caution you that some of the advice you are getting in this thread is bogus, at best.

Let's start with the basics: available motor torque is a function of the V/hz ratio.

The motors you have are 60hz base speed and are dual wound for 230VAC and 460VAC. This means that the insulation is good to at least 460V.

Your supply is 380V 50hz and you want to run the drive and motor at this voltage and frequency.

You want to preserve the torque producing capacity of the motor which, in effect means that the V/Hz ratio must be preserved.

OK, with those principles in mind, why not keep the existing motors, keep them connected for 230VAC 60hz (3.83V/Hz), buy a 380V drive with the ampacity needed for the motor connected for 230V 60hz, and set the drive up with the motor data being entered into the drive modified to 380V and 99Hz. That's still a V/hz ratio of 3.83 and the voltage is also under the 460V capability of the insulation. This would give you a motor with the same available torque from zero up to 99hz. You don't want that much speed? OK, set the speed or frequency limit on the drive to 50hz.

You've just created a 380V 50hz system with the 230V 60hz drive.

Now, what did I leave out?

NOTHING AND IT`S SOME GOOD ADVISE !!!