2 Pole Vector Duty Motors

Anyone have any suggestions on where to source 2 pole vector duty motors? We have a customer who wishes to direct couple to a load and adjust the speed range between 900 and 4800 rpms. We would require full torque at 4800rpms. Looking to de-rate a 2-pole vector duty motor (460VAC, 60hz,5 to 10 hp yet to be determined) and overspeed to 4800. Only problem is it looks like 2-pole vector duty motors are not very popular. Anybody have something they would like to recommend?

DamianInRochester said:

Anyone have any suggestions on where to source 2 pole vector duty motors? We have a customer who wishes to direct couple to a load and adjust the speed range between 900 and 4800 rpms. We would require full torque at 4800rpms. Looking to de-rate a 2-pole vector duty motor (460VAC, 60hz,5 to 10 hp yet to be determined) and overspeed to 4800. Only problem is it looks like 2-pole vector duty motors are not very popular. Anybody have something they would like to recommend?

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Automation Direct has 10 hp marathon motors
http://www.automationdirect.com/adc...)/Marathon_Inverter_Duty_Motors_(by_HP)/E2018 They also have 5hp motors
http://www.automationdirect.com/adc...)/Marathon_Inverter_Duty_Motors_(by_HP)/E2012

You are aware that to get full torque at 4800 RPM you will have to have a VFD rated at twice the 480 amps for your motor. Then you will have to make the connections in the peckerhead for 240 volts. Then program a custom V/Hz curve that will deliver 240 volts at 60 Hz and 480 volts at 120Hz.

The method milldrone has given you will work as I have used it in the past but the average maintenance guy will really screw it up if he ever has to troubleshoot it.

If it were me I would consider using a direct drive torque motor and drive http://www.automation.siemens.com/m...t-drives/torque-motor/Pages/torque-motor.aspx

I use these quite a bit here and they perform well.

Forget my first post the siemens torque motors speed does not go above 900 rpm.

Assuming the term "full torque" means the nameplate torque of the motor at base speed extended out to the 80hz, 4800rpm point, that would mean that the motor needs to develop 1/3 more hp at 4800rpm than at 3600rpm.

In my opinion, the easiest way to do this is to buy a two pole motor at least 1.33 times larger than the normal hp at 3600rpm. So, for example, buy a 7.hp motor for the 5hp application, a 10hp for the 7.5hp, and a 15hp for the 10hp. Run the motor into field weakened range at 80hz with the motor reaching 460V at the normal 60hz.

You will have all the torque you need. The wiring and control will be normal. The motor will handle the load and cool better at all speeds. The drive will have to be sized to the larger hp rating. The only real disadvantage of this is that the motor may be a frame or two larger. If you've got room for it, you've got your solution,

You could do what milldrone suggests with wiring a 10hp 9 lead dual voltage motor in its 230V configuration and setting the drive to 230V at 60hz and 460V at 120hz. This would work just as good but, while the motor would stay at 10hp, you would need to double the drive current rating to about double hp.

I think my way might be a bit cheaper and would preserve the conventional look to the wiring, etc. but either would be a workable solution, if properly done.

Hi Dick, your assumption is correct. I was basically just going to go up a size so that at 80Hz I would have at least the HP I did at 60Hz with the smaller motor.

Reading back through this I realized that I failed to mention a critical detail. I want to run this thing in closed loop vector mode. I wanted to get the motor with a rear mounted encoder. Like the Marathon BlackMax or the Baldor ZDNM series, etc.

If I went with a BlackMax Y545-A772 for example, it lists the max safe rpm as 4200RPM. Probably because the base speed is 1800RPM. I just don't understand why I can't find a vector duty motor with rear mounted encoder with a base speed of 3600 (2 pole).

Thanks everyone.

Would baldor be okay?

http://www.baldor.com/products/prod...vw_ACMotors&phase=3&rpm=2800-3600&voltage=460

I had some situations at a previous employer where I needed motors that were not commonly offered with encoder, but had to purchase separate kits to install in-house. Those were reliance motors, IIRC, but your favorite company may offer a separate encoder mounting kit option.

The Turck A02H encoder fits on the back of Baldor or Marathon motors and is rated @ 6000 rpm
http://www.turck-usa.com/Products/Encoders/Incremental,_Shaft~Hollowshaft/Heavy_Duty.htm

In constant horsepower loads, the same amount of horsepower is required by the load from base speed to maximum speed. As machine speed increases, the amount of torque required decreases.
>Maximum speed is the most RPM that can be produced by a motor. It is based on the motor's electrical limitations.
>Running above the motor base speed the motor will enter into a so called "field weakening point" where the torque decreases significantly.

What vector drive are you going to use
If a Powerflex 755 then use a servo motor, base speed could be 5000 rpm

This exercise has forced me to re-evaluate my understanding of what the difference is between the construction of an Inverter Duty motor as opposed to a Vector Duty motor. I am having difficulty finding any clear distinction between the two. Is it to a large degree that "Vector" motors are just "Inverter Duty" motors with an encoder?

They mean the same thing just different terminology from different companies.

The only thing that makes a motor vector,inverter,VDD duty is the insulation type which is rated for a higher temp and to take higher voltage spikes.

Just like premium efficent motors are primarily better ironm and lamination methods, better magnet wire,closer air gap,and better cooling.

A drive though can be a inverter /vsd but not be a vector drive.

Non vector drives are caled volts per hertz or scalar drives or just VSD.

The tem VSD can be used for vector and non vector drives.

Unfortunately, Damien, the terms "inverter ready", "inverter rated" and "inverter duty" are undefined and many marketing departments of motor manufacturers have run AMOK with these terms. They are meaningless.

What is carefully defined, however, is MG1 Part31 of the NEMA motor specification. MG1 Part31 requires that the motors pass an insulation test on PWM pulse power of 1800V (normal motor testing is on sine wave power at 1200VAC). In addition, the motor must have high temp grease in its bearings. That's a real spec and one you can trust.

What is not included in any of these specs is motor cooling limits. You can have an ODP motor capable of turndown only to 30hz at full rated torque or an auxiliary cooled or TENV motor capable of developing full rated torque at zero speed. The cooling aspect you have to define for your application and pick your motor type accordingly.

The pulse power test of the MG1 P31 motors doesn't define just how a manufacturer acheives this higher level of insulation integrity. That's left to the manufacturer and may or may not include extra phase paper, concentric winding, special wire enamel, etc etc etc. They all have something "special" that they will use as a marketing tool. But the bottom line is the spec. If it has the MG1 P31 endorsement, you've got a much better motor when used on PWM power.

Of course, there are limits to that motor too but that's another thread!