Problems between Frenquecy Invertor & Motor

eMpty · Sep 30, 2011

it seems not that difficult but it's really hard for me.

i've got a Rockwell PowerFlex 700 380VAC-3Phase Frenquecy Invertor and a SEW 220VCA-Delta 3Phase Motor.How can i drive this motor.Change wiring from delta to star is forbiddened by the motor supplyer,so any help?

DickDV · Oct 1, 2011

Without the delta to star conversion, you've got an incompatible VFD and motor. Whatever your main supply voltage is, your VFD and motor should be the same.

sthompson · Oct 1, 2011

eMpty said:
it seems not that difficult but it's really hard for me.

i've got a Rockwell PowerFlex 700 380VAC-3Phase Frenquecy Invertor and a SEW 220VCA-Delta 3Phase Motor.How can i drive this motor.Change wiring from delta to star is forbiddened by the motor supplyer,so any help?

Most SEW Motors are Dual Voltage set by Jumpers. I presume yours is a 220/380VAC. While it would be possible to set up the VFD to run the Motor at 220VAC, you have to realize that it will require more Current to do the same work. Your VFD might not be up to the job.

What is the Supply Voltage? 380VAC 3PH 50Hz?

What is the exact PF700 Model and Ratings?

Why is it a problem to set the Motor up in Star?

As Dick stated, the setup you have described is very poor.

Stu....

bce123 · Oct 1, 2011

Stu, Dick, Long ago I did a deep well down hole pump app that required the output of the drive to be around 4160? its been quite a while these were typically feed from a 480 to 4160 xfmr and a 4160v drive the down hole pump motor was 480v . In late delivery situation we decided to use a temporary 480v drive and feed the xfmr with it. It worked so well that the company started using this setup on other locations because of the cost savings not having to buy the 4160 line side equipment never done it since but it does work. any feed back on this and could it help the OP?

eMpty · Oct 2, 2011

sthompson said:
Most SEW Motors are Dual Voltage set by Jumpers. I presume yours is a 220/380VAC. While it would be possible to set up the VFD to run the Motor at 220VAC, you have to realize that it will require more Current to do the same work. Your VFD might not be up to the job.

What is the Supply Voltage? 380VAC 3PH 50Hz?

What is the exact PF700 Model and Ratings?

Why is it a problem to set the Motor up in Star?

As Dick stated, the setup you have described is very poor.

Stu....

Supply Voltage is 380VAC 3PH 50Hz,You're right.

PF700 Model is 20BC030A0AYNANC0,15KW.The motor is 11KW with an oil pump

Problem with change wiring is that it only shows 220VAC Delta on the nameplate,so i'm not quite sure that Changing jumper is OK.I've uploaded the nameplate so you can check it out.Thx.

sthompson · Oct 2, 2011

The PF700 you listed is rated at 30A, and the FLA listed on the Motor Plate is 37.5A. According to the Motor Plate, it is 230VAC 3PH Delta only, too bad. The only choice I see is replacing the 230VAC Motor with a 380VAC Motor. This should bring the Current down to within the rating of the PF700 VFD.

Stu....

sthompson · Oct 2, 2011

bce123 said:
Stu, Dick, Long ago I did a deep well down hole pump app that required the output of the drive to be around 4160? its been quite a while these were typically feed from a 480 to 4160 xfmr and a 4160v drive the down hole pump motor was 480v . In late delivery situation we decided to use a temporary 480v drive and feed the xfmr with it. It worked so well that the company started using this setup on other locations because of the cost savings not having to buy the 4160 line side equipment never done it since but it does work. any feed back on this and could it help the OP?

I have never tried it. I am not sure how the Transformer would respond to PWM Input, and the varying Frequency. Maybe DickDV has seen this.

Stu....

eMpty · Oct 2, 2011

sthompson said:
The PF700 you listed is rated at 30A, and the FLA listed on the Motor Plate is 37.5A. According to the Motor Plate, it is 230VAC 3PH Delta only, too bad. The only choice I see is replacing the 230VAC Motor with a 380VAC Motor. This should bring the Current down to within the rating of the PF700 VFD.

Stu....

Not too bad 'cuz i've got a backup VFD which is 15KW Heavyload,FLA is 37 Amp.so current may not the problem.
But I've heard from someone else that the BUS DC in this VFD is too high(about 580 VDC),it may do some harm to the motor coil when running.Is this true or just fake?
Another,someone said setting the standard Hz to 87Hz then give 50Hz with 380VAC,the volt can be lowered to 220VAC,is that right?

BTW,thx 2 much 4 answering!

sthompson · Oct 2, 2011

eMpty said:
Not too bad 'cuz i've got a backup VFD which is 15KW Heavyload,FLA is 37 Amp.so current may not the problem.
But I've heard from someone else that the BUS DC in this VFD is too high(about 580 VDC),it may do some harm to the motor coil when running.Is this true or just fake?
Another,someone said setting the standard Hz to 87Hz then give 50Hz with 380VAC,the volt can be lowered to 220VAC,is that right?

BTW,thx 2 much 4 answering!

Bus Voltage:

Yes, it is a valid concern. The SEW Motor Plate says it is Inverter Rated. This usually involves better Winding Insulation, and better support of the Winding in the Stator. With PWM the VFD Output Voltage is switched from 0VDC to the DC Bus Voltage pretty quickly. For 230VAC 3PH I believe the DC Bus Voltage would be about 350VDC or so compared to the 580VDC you quoted. So, over time the Higher Voltage and fast switch rate could cause damage to the Motor Windings.

Lower Output Voltage:

Yes, you can Program the VFD to limit the Effective Output Voltage to 230VAC. However, this does not address the higher Bus Voltage concern. The VFD will still switch from 0VDC to the 580VDC Bus Voltage.

Stu....

eMpty · Oct 2, 2011

sthompson said:
Bus Voltage:

Yes, it is a valid concern. The SEW Motor Plate says it is Inverter Rated. This usually involves better Winding Insulation, and better support of the Winding in the Stator. With PWM the VFD Output Voltage is switched from 0VDC to the DC Bus Voltage pretty quickly. For 230VAC 3PH I believe the DC Bus Voltage would be about 350VDC or so compared to the 580VDC you quoted. So, over time the Higher Voltage and fast switch rate could cause damage to the Motor Windings.

Lower Output Voltage:

Yes, you can Program the VFD to limit the Effective Output Voltage to 230VAC. However, this does not address the higher Bus Voltage concern. The VFD will still switch from 0VDC to the 580VDC Bus Voltage.

Stu....

So at last,i can drive this motor in this way,but it will be breaked down sooner or later,maybe several years later......,

DickDV · Oct 2, 2011

sthompson, I've seen 480V drives inserted into 4160V systems via a 4160/480V transformer on the input and a 480/4160V transformer on the output but those systems had 4160V motors. It sounds like the system described above has a 4160V transformer output feeding a 480V motor down the well casing.

That I've never seen and can't imagine how that would be a good idea unless the motor leads are so long that the 60Hz voltage drop was so large that the 4160V you start out with is down to 480V at the motor. Imagine the lost energy in the motor leads doing it that way.

Something just doesn't seem right in the original description of the system.

bce123 · Oct 2, 2011

the motor leads are so long that the 60Hz voltage drop was so large that the 4160V you start out with is down to 480V at the motor. Imagine the lost energy in the motor leads doing it that way.

Dick this was used on a deep oil well If I recall it was around 4000 to 5000 feet We used armor shielded high voltage cable 5kv stuff.I believe it was a REDA pump made in OK.
But I don't know If this Would be worth trying for the OP or for anyone as the cost of the xfmr would be about the same as the drive and I am not sure what effects it would have on the motor?
Best regards, Steve

sthompson · Oct 2, 2011

DickDV said:
sthompson, I've seen 480V drives inserted into 4160V systems via a 4160/480V transformer on the input and a 480/4160V transformer on the output but those systems had 4160V motors. It sounds like the system described above has a 4160V transformer output feeding a 480V motor down the well casing.

That I've never seen and can't imagine how that would be a good idea unless the motor leads are so long that the 60Hz voltage drop was so large that the 4160V you start out with is down to 480V at the motor. Imagine the lost energy in the motor leads doing it that way.

Something just doesn't seem right in the original description of the system.

I had to read it twice, but what I took away from it was that they were sending 4160 down to hole to 480VAC Motor. I am as mystified as you are about that, but I have no experience with that kind of operation.

Stu....

bce123 · Oct 2, 2011

Yes, it was a Long time ago and I'm not sure about the brand we used several different brands but REDA sticks out maybe because my brother was a drive tech for them at one time. I think nowadays they use two xfmrs like you described above.

DamianInRochester · Oct 2, 2011

eMpty said:
But I've heard from someone else that the BUS DC in this VFD is too high(about 580 VDC),it may do some harm to the motor coil when running.Is this true or just fake?
Another,someone said setting the standard Hz to 87Hz then give 50Hz with 380VAC,the volt can be lowered to 220VAC,is that right?

BTW,thx 2 much 4 answering!

This is a game sometimes played with IEC motors.
Here is a good explanation of what this is referring to.

http://www.inverterdrive.com/HowTo/Increase-Motor-Power-Output-and-Speed-by-73-delta/default.aspx

I personally hate seeing it done because it creates considerable confusion. People will see it and naturally think it is a mistake. I hasten to even mention it as an option, although many swear by it.

Problems between Frenquecy Invertor & Motor

eMpty

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DickDV

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sthompson

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bce123

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eMpty

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sthompson

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eMpty

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eMpty

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bce123

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sthompson

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bce123

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