380/60hz motor on 380/50hz circuit
380/60hz motor on 380/50hz circuit
(OP)
So knowing what I know about electric motors, which is nothing, why wouldnt this work with a VFD? Can I just "turn the knob" on the VFD to give the motor the 60hz its looking for to negate the 17% loss I would normally occur without a VFD?
My bet is its not that easy since nothing is that easy.
My bet is its not that easy since nothing is that easy.





RE: 380/60hz motor on 380/50hz circuit
RE: 380/60hz motor on 380/50hz circuit
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If we learn from our mistakes I'm getting a great education!
RE: 380/60hz motor on 380/50hz circuit
Is there a single load that couldn't be VFD run? Note: I'm asking 'couldn't' not 'shouldn't'.
Keith Cress
kcress - http://www.flaminsystems.com
RE: 380/60hz motor on 380/50hz circuit
Some bearings don't behave well at low speeds - white metal types can't form the oil wedge or example - and anything which drives its own lube pump from the main shaft may not be too happy with prolonged running at low speed.
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If we learn from our mistakes I'm getting a great education!
RE: 380/60hz motor on 380/50hz circuit
In other words, if you are running a 380V 50Hz motor at 60 Hz, search for the recent thread on this topic.
rmw
RE: 380/60hz motor on 380/50hz circuit
Are you sure that the motor is rated for 380 Volts at 60 Hertz? Much of the 60 Hz world is also NEMA world and NEMA standard motor voltages are multiples of 115 Volts.
115 Volts
230 Volts
460 Volts
575 Volts
380 Volts at 60 Hz is not a standard voltage.
Bill
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"Why not the best?"
Jimmy Carter
RE: 380/60hz motor on 380/50hz circuit
The issue is I already this motor in 60hz. Buying another explosion proof motor in 50hz clothes means going up a frame size and adding 2000 bucks to the cost. If I can save about $11k - I would like to.
RE: 380/60hz motor on 380/50hz circuit
RE: 380/60hz motor on 380/50hz circuit
Im hung up on this. Since HP is calculated by (Eff X V X Amps)/746 I wouldnt be losing any HP when hooking this motor up to 50hz. I would still lose torque though because I would lose speed BUT if I make the VFD provide the motor with 60hz then I should be running the motor as it was designed right?
RE: 380/60hz motor on 380/50hz circuit
Bill
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"Why not the best?"
Jimmy Carter
RE: 380/60hz motor on 380/50hz circuit
RE: 380/60hz motor on 380/50hz circuit
You either have to de-rate the motor or use a VFD to get back to 60Hz.
RE: 380/60hz motor on 380/50hz circuit
A motor is DESIGNED around a voltage and frequency and thereby the RaTIO of the voltage and frequency becomes critical. If you mess with that ratio, you mess with the motor's performance and capabilities.
You said this is going to China, they are 380V 50Hz. No problem.
But you ALSO said that you have a 380V 60Hz motor. That is what we are saying is unlikely. There are only a small number of countries that actually have 380 or 400V 60Hz power; Brazil, parts of South Korea, parts of Tahiti, parts of Suadi Arabia, the Philipines and several of the Leeward Island Nations of the Carribean. With the exception of Brazil and South Korea, most of those countries do not manufacture motors for export, and the two that do make the 380V 60Hz versions pretty much just for domestic use. So if you do indeed have one, it's an oddball.
But if you investigate it, a 460V 60Hz designed motor has a V/Hz ratio of 7.67:1, and a 380V 50Hz motor has a V/Hz ratio of 7.6:1, so close we consider it the same. Those motors will each put out the same torque. So if you have a 380V 50Hz supply, you can use a 460V 60Hz designed motor just fine. But it will spin 17% slower (50/60) and therefore put out 17% less power (same torque, lower speed). BUT THE TORQUE REMAINS THE SAME in both cases.
So if your motor is doing work that is related to torque, you don't need to do anything. If the work is directly related to POWER, as in kW or HP, then you have to do something; it all depends on the type of load you have. Screw Extruders tend to be torque related loads, meaning you are not necessarily sizing the motor to maintain a particular speed, you are more concerned with having the right amount of shaft torque at the opearting end of your gearbox. You may end up extruding a little slower, but you will not stall the motor.
Now a SEPARATE issue brought into the fray by ScottyUK is that, REGARDLESS of the fact that it is an "Inverter Duty" motor, the regulations for "Explosion Proof" applications in some countries require that SPECIAL motors be used for inverter use in explosive areas. We don't have those rules here in the US, so you may not have been aware of that. But ScottyUK, being NOT in the US, is giving you fair warning that this may in fact rear up to bite your backside when it arrives in China, where the solution will cost you FAR more than whatever you have to spend here to deal with it ahead mof time.
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RE: 380/60hz motor on 380/50hz circuit
jref
I noticed this on a lot of motor nameplates. Most motors I see have a 50/60hz stamped on them. So I assuming the motor is made to work at the lower freq since it has to be bigger in size for ths 50hz frequency.
So basically the poster could of bought a explosion proof 460vac motor, and just raised the frequency on the VFD to get the necessary speed out for this torque application?
RE: 380/60hz motor on 380/50hz circuit
Bill
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"Why not the best?"
Jimmy Carter
RE: 380/60hz motor on 380/50hz circuit
rmw