Can a motor rated for 460VAC 3-Phase 50Hz be used with 400VAC 3-Phase 60Hz Power 8

[colombo7]

Motor Data:
7.5 kW 230/460V 50 Hz.(Delta or Y Configuration)

Does the above mean if Plant supply 460VAC (more than likely 480VAC) is connected to the motor using a DELTA connection that it is running at 230VAC and if connected in a "Y" configuration motor is being supplied 400VAC?

Can this motor be used with incoming power (Plant power) set at 400VAC at 60 HZ using a VFD?

Thanks.

 

[LionelHutz]

Does this mean I need 230VAC line power if I want to run this motor using the DELTA connection and 400VAC incoming line power to connect it using the Wye configuration? I was under the assumption if I had incoming power at 400VAC I can still use that to run the above motor configured in a DELTA configuration and the motor would see 230VAC as its supply voltage.

Regarding your last sentence...

With a VFD, you could. But the VFD created motor supply voltage wouldn't simply be 230V, it would vary in voltage and frequency as you started and stopped the motor and when you changed speeds.

Without a VFD, the motor connection has to match the incoming voltage, or to be more exact you need to make sure the V/Hz ratios of the motor and source match. Hence why 480V @ 60Hz could work as the source.

Read my and the other posts again since it was explained already. If you can't get that to connect then you need to get some books on the subject of using VFD's because this isn't a teaching site.

Bonus points to the person who correctly guesses why I setup the VFD to produce 460V@6.7Hz.

 

[colombo7]

LionelHutz

Thanks for the help.

Just curious...

this isn't a teaching site.

So if everybody here knows everything, what exactly is the purpose of this forum? I see people asking questions all the time on this section. It is more like 95% asking for some sort of help vs. Sharing new ideas.

Is there a disclaimer that I missed before i registered?

 

[RRaghunath]

Colombo7, Just to clarify -
# when you apply 400V to the motor with 'star' connected windings, what is the voltage across each of the phase windings: 230V (i.e. 400/sqrt3). Isn't it!
Now,
# when you apply 230V to motor with 'Delta' connected windings, the voltage across each of the phase windings is 230V.
What is important here is the voltage applied across the windings and that should remain constant (for a given frequency).
Hope the explanation is helpful.

 

[colombo7]

Hi RRaghunath,

Thanks for the reply. I never thought of it in that that way (just didn't know the math involved until you pointed it out.) I've realized that I have got a lot of reading to do on the subject of Induction motors and 3 Phase AC in general. So with my limited to non existence knowledge on the subject matter, is it suffice to conclude from the information given so far that Delta connection is used for light duty tasks where as Wye connection is used for heavy duty tasks in simplistic terms? OR, do they do the same amount of work based on the available supply voltage at either 230 or 400 vac with the same motor configured either in Delta (for 230VAC) or in Wye (for 400VAC)?

Thanks again. Much appreciated.

 

[waross]

Lionel; Was that set up as a torque motor to take up slack or was it inching operation.
Gee V/Hz = 0.01457, The rated voltage at 60 Hz = 4120 Volts
Probably inching a 4160 Volt motor for alignment. Too big for a torque motor.

columbo7 The thing is; when we ask the questions we understand the answers.
You have been lucky. We usually don't do this much teaching.
Many are bounced after the second or third post.
Be grateful for the help that you have been given.

p.s. Re the 100 Hz operation. that may be a trick more often used by compressor skid builders.
By running a motor at double voltage and double frequency, you double the HP.
This is sometimes done so as to use a smaller motor.
BUT
The manufacturer has to use a pump that will not overload the motor at 6000 RPM.
Yes, it can be done at the design stage, but you can not generally overspeed a centrifugal pump by very much.

And yes I have seen something similar done in a special case.
We needed a head of about 200 feet. The smallest pump capable of producing that head was much too large for the application.
The pump shop extrapolated a pump curve to find the RPM needed to develop the head required. They then calculated the HP required.
A suitable motor was selected and the pump was belt driven above the motor speed to get the 200 foot head.
That pump would normally have a motor of about 15 HP or 20 HP. At the increased speed, we needed 30 HP.
When you start talking about pump drives you must consider the pump as well as the motor.
Oh, and by the way, I haven't seen everything but 400 Volts @ 60 Hz is pretty rare in North America. What type of plant is this?

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[LionelHutz]

Bill - Yes, inching a ball mill.

colombo7 - OK, this isn't the site to get taught a complex subject from scratch. For example, you should have done some Google learning to know how wye vs delta worked.

Regarding your last question. By now you should already know:

- that the motor HP remains the same so the motor can do the same amount of work at either voltage.

- that the voltages need to be matched when the motor is directly connected to the source.

- that with a VFD you could use either voltage connection along with the matching source voltage to run the motor up to 50Hz.

- That the lower voltage connection using a higher voltage source allows the motor to run up to a higher frequency (and speed) that matches the source (using the V/Hz ratio) without losing motor torque.

Something not yet made clear is that you generally pick the higher voltage possible at the site for motor installs since a higher voltage lowers the current which makes the wiring and the equipment cheaper.

I haven't posted anything about the load because it could take another book or two to fully explain what various loads do as the speed changes.

 

[ZaraSailor]

Hi Colombo7,

Here is an overview video about the differences between WYE and Delta :

https://www.youtube.com/watch?v=3ktxtDW6UAE

Here is some Basic information about stepper motors:

https://www.accu.co.uk/823-motors

We still don't know your application and I'm guessing that there might be a fan connected to the supply. Therefore, I'd like to mention that a decrease in power could have a detrimental affect on the performance of the fan system, which will cause your machinery to overheat.

Kind regards,

Zara