Problems between Frenquecy Invertor & Motor

[eMpty]

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.

yep,sounds so strange but some ppl say it gonna works......,so,is that a choice?

 

[DickDV]

Damian, the effective voltage to the motor may be limited to 220V but the PWM pulse height is 600VDC, just the same as if you were making 400VAC. That's the concern since the 220VAC motor insulation may not be able to withstand the pulse voltages.

 

[DamianInRochester]

Damian, the effective voltage to the motor may be limited to 220V but the PWM pulse height is 600VDC, just the same as if you were making 400VAC. That's the concern since the 220VAC motor insulation may not be able to withstand the pulse voltages.

Hi Dick, I agree completely. One of the many reasons I hate seeing it done. Most people just assume the windings insulation can handle the extra voltage.

 

[DamianInRochester]

yep,sounds so strange but some ppl say it gonna works......,so,is that a choice?

My suggestion is call up SEW, give them the serial # of your motor, and see if they give you their blessing.

 

[eMpty]

Hi Dick, I agree completely. One of the many reasons I hate seeing it done. Most people just assume the windings insulation can handle the extra voltage.

yep,that's the weak point.If it can stay until i finish this huge project.that's not my problem then,

 

[DamianInRochester]

yep,that's the weak point.If it can stay until i finish this huge project.that's not my problem then,

Only your reputation!

 

[eMpty]

Only your reputation!

sad......,ppl who selected this motor don't agree to change another one,'cuz it costs a lot of time to carry the huge thing to China oversea.so i can't do the magic.

 

[OkiePC]

sad......,ppl who selected this motor don't agree to change another one

Welcome to our world.

If I had a nickel for every time I had to program around someone else's poor hardware choice or decision not to stock spare parts...

For a small HP motor this is usually not too big of a concern. Typical Boss eaction, "So the $180 motor only lasted a year? And you want to pay $400 for one that is supposed to last longer?"

Now in your case, the motor won't be so cheap, but should still be suggested as your replacement part. If you are responsible for the electrical drawings, put a note on there with the correct part number for inverter rated motor or a note...a little CYA.

I admit I know nothing of the manufacturing practices in use by Sew, but it would not surprise me if the motor insulation was more than adequate for 600V peaks. So, the motor might last a decade and we worry for nothing.

 

[eMpty]

Welcome to our world.

If I had a nickel for every time I had to program around someone else's poor hardware choice or decision not to stock spare parts...

For a small HP motor this is usually not too big of a concern. Typical Boss eaction, "So the $180 motor only lasted a year? And you want to pay $400 for one that is supposed to last longer?"

Now in your case, the motor won't be so cheap, but should still be suggested as your replacement part. If you are responsible for the electrical drawings, put a note on there with the correct part number for inverter rated motor or a note...a little CYA.

I admit I know nothing of the manufacturing practices in use by Sew, but it would not surprise me if the motor insulation was more than adequate for 600V peaks. So, the motor might last a decade and we worry for nothing.

i'll call SEW 4 certain details,if so,i'll be very glad,if not......,

 

[DickDV]

OkiePC, you bring out an interesting point. I've heard several manufacturers say unofficially that they only stock and use one type of insulated wire and one type of insulation system for all their motors regardless of the Low Voltage voltage rating.

If that is true, then, while each ratings' coils would be wound differently, they would have the same voltage withstand capacity (600VAC in North America, 690VAC elsewhere).

I'd be leery about actually using that rule unless there is some kind of official statement to that effect but it is more than likely true.

 

[DamianInRochester]

If you do end up going that route, for the sake of all who will come across it or service it in the future, please put tags/signs/stickers and some other documentation on both the motor end and the drive end to explain that it was done intentionally and why. If something ever goes wrong with it down the road, the first thing people are going to look at is the wiring and the parameters. They are going to see strange parameter settings and the mismatched wiring and assume it is wrong and start to fiddle with it and make things worse.

 

[DamianInRochester]

OkiePC, you bring out an interesting point. I've heard several manufacturers say unofficially that they only stock and use one type of insulated wire and one type of insulation system for all their motors regardless of the Low Voltage voltage rating.

If that is true, then, while each ratings' coils would be wound differently, they would have the same voltage withstand capacity (600VAC in North America, 690VAC elsewhere).

I'd be leery about actually using that rule unless there is some kind of official statement to that effect but it is more than likely true.

Dick, I almost wonder whether that should also be on the motor nameplate as well. I'm suprised it isn't.

 

[nonuke]

We have been using the 87Hz system for a long time, and it works.
This way, we buy a lower power motor (30KW)and a 1.73 times the power drive (55kW).
Siemens has a good explanation and drive configuration.

https://support.automation.siemens....lib.csinfo&lang=en&objid=21139232&caller=view

 

[eMpty]

Things got more interesting.I've received an E-Mail from Sub-contractor who provides me the whole hydraulic drivers:

"Hello!
Our technician replied to your request:
The hydraulic power pack is designed to be driven with a frequency of 87 Hz to achieve the nominal lifting speed and lifting time. To run the motor with 87 Hz it has to be connected in delta connection as supplied.
If it would be wired to star connection with 400 V it could be ran with 50 Hz only.
With that connection and the reduced current a lifting speed of approx. 145 mm/s instead of 250 mm/s could be achieved (resulting total lifting time approx. 13 s)
Please let us know if you need more details"



Don't really know what "a frequency of 87HZ" means,telling me i can drive the motor with a frenquecy convetor whose Standard Ouput Frenquecy is 87HZ and the actual output frenquecy should be setted at 50Hz so the actual output Voltage is 220VAC?

Professional Help,buddies!

 

[Pego]

50Hz 230V motor driven at 87Hz 400V

Have a look at this document:

http://www.sew-eurodrive.de/s_training/teachware/pdf/WB_Grundlagen_Antriebstechnik_en.pdf

and read page 32 - 34.