Wrong voltage for phase converter. 1

[melleryg]

I ordered an ARCO M230XD phase converter for a customer who was moving his printing press from his old shop (with 120/240 three phase) to a new shop (with 120/240 single phase). When we got access to the new shop it turned out to have 120/208. The shop is in a 12 unit mini-mall.
Can I make this phase converter work?

 

[dV8r]

I do not know, what is the voltage input requirement for your phase converter?

 

[waross]

I would investigate the possibility of a three phase service.
With 120/208 volts, the mall will be supplied with 120/208 three phase and there will be three phase at the main metering center. You may already have three phase in the panel.
To use the phase convertor on 208 volts, you may have to add more capacitance. At 208 volts, the motor will draw more current. The current draw of the phase convertor will increase even more. The phase convertor may be overloaded running at 208 volts.
Then again, if the motor is lightly loaded and the phase convertor is oversized the operation may be acceptable.
It depends.

 

[dV8r]

You may be able to add a buck/boost tx.

 

[melleryg]

Thanks for the tips. The Model M Roto-Phase is rated for 230 volts input, and will drive up to a 3 HP motor.

The local power company told me that the mall was supposed to be 120/240 with a delta bank. But the customer mistakenly ordered a 12 unit metering package that was wired for 120/208 wye. I will take another look at the meter panel and see if there are any 3 phase sockets.

Probably the lowest cost option is to add a boost transformer.

Thanks.

 

[waross]

If you can return the phase convertor for credit I would try to go for a three phase service.
If the cost of three phase is prohibitive, then I would add a boost transformer. I wouldn't like it but I would use it. It will put your phase convertor and motor back to rated voltage and avoid derating issues.
I would use a 240:32 volt transformer rated for boost service.
This should give you 235.7 volts when fed from a 208 volt source.
If this is not available use a 240:24 volt transformer. If it has voltage taps, set them for all the extra voltage you can get. This should give you 228.8 volts when fed from a 208 volt source.
Remember that 230 volt motors are normally fed from 240 volt sources.
To determine the capacity, use the rated input current of the phase convertor/motor combination.
Select a transformer with the 24 volt winding rated for this current. One of the advantages of the autotransformer boost connection is that the transformer size is roughly the inverse of the boost ratio. That is, a 1KVA transformer used to boost the voltage 10%, will boost 10 KVA of power.
In your case, I suspect that a transformer of about 500VA to 750 VA may be adequate, but please do the math yourself with the actual nameplate values. If in doubt about the size, go to the next larger size.
respectfully