converting motors to voltages used outside the US 1

[HBtheElectrician]

I have a 240volt 60HZ motor, I believe it is a 5 horse, however the name plate states it is "Special" and is continuous duty . The motor goes on an air compressor that is in Togo Africa. When I received it the start capacitor was blown and it appeared that the start windings had gotten warm. The power in Togo is 230volt 50hertz. It is my understanding that to keep the motor from overheating one would have to bring the voltage down to 80percent of the nameplate, so this was my first thought. I have not ever dealt with power in other countries and I am not how it is used. I was looking into voltage converters, but when it started to talk about converting from 110/120 to 230/240 I got a bit confused. Here in the US when you are speaking of 240 single phase you are speaking of 2 hot wires. So, when you are speaking of 230 in Togo Africa are you still speaking of 2 wire single phase?

 

[itsmoked]

Yes, still two wires. There are lots of problems with attempting this.

Check out the FAQ: faq237-1224 which discusses them all.

The biggest problem with an air compressor is starting. You have a reduced starting toque that can dial-up excessive starting times that blitzes the windings and the capacitor. Often your system can't get up to speed so the centrifugal start switch can't transition out of start and this toasts everything - the very first time.

You need a way to reduce the speed at which the switch transitions the start winding out. Not easy to do...



Keith Cress
kcress -

http://www.flaminsystems.com

 

[HBtheElectrician]

Ok so the user of this motor claims that he has someone who can switch this motor over to a 50 hertz motor. How is this done? Is this a good idea?

 

[VEBill]

Developing nations tend to have plenty of people that can (for example) completely rewind a motor to meet a different spec. Obviously there's some risk that they don't actually know what they're doing.

It's a possibility worth exploring. Carefully.

 

[MikeHalloran]

If you're producing motorized goods for export, you really need to engineer the included drives and control systems to cover at least a few of the voltage/ frequency combinations to be found worldwide, rather than relying on end users to hack your products.



Mike Halloran
Pembroke Pines, FL, USA

 

[waross]

First the voltage: The optimum voltage is 83%. That would be 200 volts IF your motor is rated at 240 Volts. Be wary. The standard North American motor voltage is 230 Volts, not 240 Volts. However 200 Volts should be within the motor tolerance.
As itsmoked says, starting may be an issue.
I would try doubling the size of the starting capacitor. I was in a situation where 1/2 HP motors were ordered instead of 3/4 HP motors and the motors stalled instead of starting. The time and place was such that if the 1/2 HP motors could not be used they had little or no value. With nothing to lose we doubled the size of the starting caps and the motors have been starting well for years now.
If the motor doesn't start immediately disconnect it and go to plan B.
Plan B: You may also try reducing the size of the pulley on the motor.

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

 

[LionelHutz]

Ok so the user of this motor claims that he has someone who can switch this motor over to a 50 hertz motor. How is this done? Is this a good idea?

I expect this someone will just install a new 50Hz motor. The compressor will run at 83% speed.

 

[Higgler]

Amazon product (link below), $400, 50 hz input (single or three phase), output 60 hz(3 phase only)(4 kilowatts, 5 hp).

Description
5hp 4kw 220-250v Variable Frequency Drive Inverter VFD with Extremely Strong Anti-jamming Capability

http://www.amazon.com/220-250v-Freq...&keywords=5+kilowatt+frequency+inverter+60+hz

Inpute Voltage: 220±15% (+/- 33 volts, so 187 to 253 VAC) (We also stock 380±15%, please contact us for item stock)

Output Voltage: 208 to 240VAC (analogous to Input Voltage)

Input Frequency: 48 to 63 Hz

Outpute Frequency: 0 to 400 Hz

Inpute Phase: 1 or 3 phase as you like

Outpute Phase: 3 phase

 

[LionelHutz]

That VFD will require a new 3-phase 60Hz motor. Just making sure there is no misunderstanding about it working with the original motor.

I should expand on what I wrote last time and add that the person could also change the pulley ratio to bring the compressor back to full speed.