3-phase convertible motor

[Farad]

Good day!

The 5 HP, 230 V, 60 Hz, 3-phase water pump motor in our office is convertible to 460 V. But the supply voltage in the new building that it'll be used is 400 V only. Is it possible to just convert the motor to 400 V instead of 460 V? Would this have an effect to the performance of the motor? I have another solution, but it would be costly, that is to convert the motor to 460 V and buy a step down transformer to 400 V. The conversion to 460 V is free of charge because it got covered in the rewinding fee. Thank you.

 

[winnie]

Is your supply voltage 400V 60Hz or 400V 50Hz?

My understanding is that the Philippines uses 60Hz power but 400V is more common with 50Hz supplies.

A 460V 60Hz motor will run quite well at 400V and _50Hz_, but at roughly 5/6 its normal rated speed.

A 460V 60Hz motor operated at 400V and _60Hz_ will have reduced starting torque and starting current, but will likely draw more current at full speed, and may not have enough torque to reach full speed, depending upon the load.

If you are getting a motor rewound it is possible to adjust its optimal voltage to any required value. In other words at the rewinding stage (not simply re-connecting wires to switch between dual voltages, but actually pulling the copper windings out and replacing them) you can adjust the voltage to suit the available supply.

-Jon

 

[Besoeker3]

Good day!

The 5 HP, 230 V, 60 Hz, 3-phase water pump motor in our office is convertible to 460 V. But the supply voltage in the new building that it'll be used is 400 V only. Is it possible to just convert the motor to 400 V instead of 460 V? Would this have an effect to the performance of the motor? I have another solution, but it would be costly, that is to convert the motor to 460 V and buy a step down transformer to 400 V. The conversion to 460 V is free of charge because it got covered in the rewinding fee. Thank you.

Or just buy a new motor rated for the voltage and frequency you want it to run at?

 

[growler]

Or just buy a new motor rated for the voltage and frequency you want it to run at?

That's normally the cheapest and best solution for the long run.

A lot of motors are not even worth having rewound these days.

 

[kwired]

for only 5 HP motor most ways of dealing with the problem cost just as much if not more than getting a different motor rated for the voltage. If it is a special design motor that would be difficult or expensive to find a 400 volt replacement for then maybe you consider other options.

 

[Besoeker3]

I think we need some feedback from OP, Farad.

 

[Farad]

Is your supply voltage 400V 60Hz or 400V 50Hz?

My understanding is that the Philippines uses 60Hz power but 400V is more common with 50Hz supplies.

A 460V 60Hz motor will run quite well at 400V and _50Hz_, but at roughly 5/6 its normal rated speed.

A 460V 60Hz motor operated at 400V and _60Hz_ will have reduced starting torque and starting current, but will likely draw more current at full speed, and may not have enough torque to reach full speed, depending upon the load.

If you are getting a motor rewound it is possible to adjust its optimal voltage to any required value. In other words at the rewinding stage (not simply re-connecting wires to switch between dual voltages, but actually pulling the copper windings out and replacing them) you can adjust the voltage to suit the available supply.

-Jon

Hi Sir, the supply voltage is 400 V, 60 Hz. So if we're going to just rewind the motor to 400 V even though it's originally designed to 460 V, is it still safe to use?Thank you.

 

[Besoeker3]

Hi Sir, the supply voltage is 400 V, 60 Hz. So if we're going to just rewind the motor to 400 V even though it's originally designed to 460 V, is it still safe to use?Thank you.

I don't see safety as an issue. Not sure it is the best way to deal with it commercially............

 

[ptonsparky]

What is the cost to rewind vs a new motor? Labor may be less expensive for you.

 

[Besoeker3]

What is the cost to rewind vs a new motor? Labor may be less expensive for you.

Or a small auto transformer. It is quite a close ratio of voltages.

 

[kwired]

What is the cost to rewind vs a new motor? Labor may be less expensive for you.

Quality of the rewind could possibly reflect that as well, just beware.

 

[Jraef]

I don't see safety as an issue. Not sure it is the best way to deal with it commercially............

Yes, I cannot imagine that it is less expensive to rewind a 5HP motor than it is to just buy one with the right specs, or just buy a transformer for it. Or, if you are buying a transformer anyway, just get a 400-240V transformer and don't touch the motor at all.