Rotary Phase Converter Comparison

What should be considered when comparing rotary phase converters?

The first item to consider is the NEMA (National Electrical Manufacturers Association) HP rating of the converter. Converters manufactured in North America (both Canada and USA products), can be referenced in terms of NEMA frame sizes.

As a general example, consider a PhaseMAXX - 5T rotary converter. The 5T is supplied in a 215T frame (of which the NEMA equivalent is 10 HP), hence, it will generally be referred to as a "10 HP converter".

While the 5T is commonly referred to as a 10 HP converter, the model number will not necessarily reflect the converter HP. Ask the converter supplier to provide the converter's NEMA HP rating.

Once you have the HP rating of the suggested converter for your application, check with other manufacturers for their converter recommendation and get the HP rating of these converters also.

If each of the various converter manufacturers you discussed the application with all suggest the same HP rating for your application, then the rest is easy:

  1. Compare price. Include any US/CAD dollar exchange + US/CAD Brokerage charges.
  2. Compare warranty.
  3. Compare Cast Iron benefits versus Cold Rolled Steel for the rotary generator.
  4. Consider the manufacturer's testimonials, history, staff knowledge, and helpfulness.
  5. Consider if the converter comes complete with a magnetic starter or if you need to purchase this separately (fusible disconnect c/w time delay fuses).
  6. Consider the converter's available soft-start magnetic starter option.
What if two manufacturers suggest a different HP requirement for your application?

Certain loads require different amounts of starting torque to be brought up to their rated speed. When an electric motor driving a particular load is connected to a phase converter that is undersized, the motor's overload relay will trip before the motor has reached its rated speed.

Some converter manufacturers fail to recognize the speed/torque characteristic of the motor and load for your specific application, and subsequently undersize the converter.

Other factors can also influence converter sizing. Each of these additional items to be considered by the converter manufacturer will also affect their suggestion for a particular phase converter HP rating.

When the converter HP ratings suggested by various converter manufacturers differ, then you must simply decide which converter manufacturer seems to have the best expertise on the subject and has provided you with the best information.

At Electram, we manufacture phase converters but our real job is to get your application up and running smoothly. We will likely talk through your scenario with you to have a well-rounded understanding of what is needed before we suggest a phase converter solution.