Phase Converters - 1 Phase to 3 Phase

[SanEnr1]

In a sewage pumping station, we have 3 phase power terminated at our property line. I have been told that connecting the 3 phase power to our equipment (designed for 3 phase power) will require a transformer whose footprint does not fit on our site. I can direct the subdivision developer to expand our property, but it was suggested to use a phase converter resulting in a transformer with a smaller footprint.

I'm looking for advice. Are there any drawbacks to using a phase converter? Any long-term issues associate with using the converter vs. the three phase power? Anything I need to be aware of for this application? Power supply is 3 Phase 240 Volt, the pump station motors operate on 3 Phase at 208 Volts. This is a 100 amp service.

 

[SteveKW]

I have seen 20 HP motors on transformer style converters so it can be done! When using that type of converter, consider going with a larger pump and then trimming the impeller so the motor is not fully loaded. The PUMP manufacturer/supplier is who you should talk to. They should have a good idea of what will work!

 

[rbulsara]

Looks like the need for the transformer is due to fact that your motor's rated voltage is much less than the supply voltage.

208V motors are good for 200-220V. Try buying a 230V motor, if you do not want to use a transformer. Tranformer is a better choice than a phase convertor which generally used to convert single phase supply to 3 phase. Transformer can also be mounted on a outdoor pole if it helps.

You may be able to apply a Variable Frequency Drive or a solid state starter than can regulate the voltage to your motor (keep it below 220V). However the the VFD shall be rated for 240V.

You did not mention the HP of your motor so your service size information is not useful.

 

[CHDean]

A 100Amp service at 208Wye would only require a 30-45 KVA transformer depending on how it is applied. These are relatively small units, 30"Hx20"wx15"d. Unless you have an underground lift station there should be a means of hanging it on a pole or structure. How big of a unit were you told you need? And rbulsara has a good point, if the motors are small enough it may be easier just to change them to 230V

 

[advidana]

sewage pumping station.
1. caution-This may be hazardous location that may require hazardous rated equipment.

2. The phase converter (motor generator type) with outdoor enclosure and associated control will have a larger footprint than a transformer of the same size. You will have the loss of the converter that will also mean a larger load. the cost will be twice as much. the convert will need to be serviced the same as any other motor.

3. If you use a soild state converter the cost go thru the roof because you will need to control the temperature a in an insultated enclosure with ventilation , heating and air conditioning. rainproof etc. You will may need a ups for the controls and on and on. There goes you footprint

4. Why can't you mount the transformer on a power pole?

Who is giving you this advice to use a converter and can he show you a typical installtion or is this just water cooler talk.

 

[SanEnr1]

Thanks to all who provided advice. We've decided to tell the developer to supply the 3 Phase power as designed by giving us more property. Our decision was based upon comments that I received implying that the phase converter will result in a decreased efficiency and that it is just an additional piece of equipment to maintain. In the long run, the designer should have spoken to the electrical utility regarding their requirements before the plans were finalized.

To answer questions posed on replies to my thread...

The motors are 5Hp operating at 3phase and 208 volts with 50amp circuit breaker on the motors.

The size of the transformer footprint is small, but the electrical utility requires the equipment to be mounted inside a 10'x10' concrete containment structure. Our pump station site is only 40'x40' and includes the station, electrical cabinet, emergency generator and associated sewer piping, etc.

The transformer cannot be pole-mounted as this is in a typical new residential subdivision with all underground utilities.

I have a phase converter on one of our 25 sewage pumping stations, but only out of shear remoteness of the facility. The converter is a small unit, but the station was built long before I began employment here and I was not involved with design.

The converter for this new station was originally proposed by an electrician as a cheaper way to get power to the station than building this containment structure for the utility supplier.

Thanks again to all.

 

[jbartos]

Suggestion to the previous posting: An additional property will provide more room for potential load growth, if applicable.