What is a Rotary Generator?

Rotary phase converters create the 3rd electrical phase by using a specially designed rotary generator. Electram has spent a considerable amount of time engineering our generators to ensure they create and maintain the 3rd electrical phase under all load conditions.

Some rotary phase converter manufacturers will simply use an electrical motor. Many 3 phase motors, when used as a generator, will have their output voltage collapse when placed under load.

Electram has built rotary phase converters for 30 years. We specifically engineered these rotary generators and they are custom built for us.

How to Compare Rotary Generators

When comparing the rotary converter of one manufacturer to another, it is important to look at the largest and total HP that it can run. To validate the largest HP rating of a rotary converter, the most reliable method is to compare the frame size of the rotary generator.

There is no governing body to determine the size of a rotary converter. This means a rotary converter manufacturer can claim whatever they want about the capacity ratings of their unit. Rotary generators, however, do have standardized sizing. The Frame size of the generator tells you its size and allows you to compare it across other brands.

Frame Size - Bigger is Better

The rotary generator needs to be large enough to start your motor. When you turn on your 3 phase motor, it will place a load on the rotary generator. If you have a big generator then it will keep on spinning when you add on the load. However, if the generator is too small then it will slow down and possibly stall out as it tries to start your motor. The more mass your generator has the bigger the “punch” it can deliver when you turn on your motor.

To compare generator sizes, look at its frame size. This is a standardized measurement system. A generator with a frame size of 256T is bigger than a 254T. If this information is not readily available, the shipping weight will provide a decent proxy because a heavier rotary converter will have a larger rotary generator.

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