What is a Rotary Frequency Converter?

A rotary frequency converter is a machine that converts power from one frequency to another frequency by means of a motor and a generator, either coupled directly or with belts & sheaves or with a gear box.  This is completed by either changing the rotational speed of the generator in the versions with belts & sheaves or the gear box and by means of motors and generators with a different number of poles operating to achieve the same result of producing the desired output frequency.  A rotary frequency converter is also capable of  producing a different voltage at the same time.  If you are operating at another voltage other than 208V, you will need to change the voltage. 

Power Systems & Controls’ Series RFC is a Rotary Frequency Converter designed to provide equipment to convert utility power into many other frequencies.  The standard frequencies are 25Hz, 50Hz, 60Hz, 100Hz, and 400Hz power. The rotary frequency converter will provide the rated kVA requirements at the output with a high-efficiency motor and common shaft or belt driven, synchronous generator to yield the required frequency and voltage.  PS&C’s rotary frequency converters are built as 2 bearing and 4 bearing solutions, as well as, vertical or horizontal configurations. A precision voltage regulator integrated within the system maintains the output voltage at (+/- .5%) far better than the industry standard.

Motor Generator = (MG set)
Common Shaft = The MG set is built as a direct coupled shaft to shaft
Single Shaft = The MG set is a single forging with motor & generator winding(s) on one shaft
Belt Drive = The MG set is positioned side-by-side and connected via belts and sheaves
Gear Drive = The MG set is connected via gear drive (box), either side by side or direct coupled with offset

Why Purchase a Rotary Frequency Converter?

There are many applications (see below) for frequency converters, however, some applications require the need for industrial grade machines with brute force, while others require the 100% isolation inherently produced by the machine.  Electric isolation is achieved by a mechanically coupled motor generator that will not allow power to pass through the shaft from the motor into the generator and visa versa.  These machines are rugged built and can survive in extreme conditions, where the Solid State equivalent will not be able to operate in the same.  

Rotary Frequency Converter Applications:

  • Aircraft Power
  • Weapons Systems
  • Manufacturing Facilities
  • Rail & Hydro Facilities
  • Sensitive Electronics
  • Test Lab & Research Centers
  • Process Automation Lines

Rotary Frequency Converter Benefits:

  • 100% True Electrical Isolation
  • Precision Voltage Regulation
  • 2 & 4 Bearing M-G Sets
  • Control & Fault Monitoring
  • Transient & Brownout Protection
  • Vertical & Horizontal Configurations
  • Common & Single Shaft Designs

Under normal operation, the Series RFC (rotary frequency converter) acts as a rotating filter with the critical load being protected from utility transients and brownouts. The rotary frequency converter is available with either a synchronous or induction motor, depending upon which product is best for the application.  A synchronous motor creates an exact frequency output with no deviation, which is ideal for testing, flight, and weapon system applications. A low slip induction motor causes the output frequency to deviate (.6Hz), which is better suited for projects that require a more economical solution.

When operated at the rated motor speed, the frequency of the generator is controlled by the RPM of the motor, thus the output frequency can be variable. It is also 100% effective for outages lasting less than 1ooms.  Also the absence of brushes and slip rings in both the motor and generator allows for virtually maintenance free operation.  Furthermore, due to its rugged design the average end of life (EOL) of a rotary frequency converter is well over 20 years. There are also numerous options available ranging from remote controls and color touch screen displays to specialized NEMA and ISO enclosures.