60Hz means the power waveform cycles 60 times per second, and 50Hz means the power will cycle 50 times per second.  These 2 frequencies are the primary reason for frequency conversion.  Before the 1900’s there were many frequencies produced worldwide utilizing Water and Steam Turbines ranging from 16Hz to 133Hz.  However in the early 1900’s, the electric power grids standardized on 50Hz and 60Hz AC power.  The origins and actual inventors has been a topic for conversation, but it is clear that Edison, Tesla and Westinghouse were all involved.

frequency conversion

The Graph above shows the difference in waveform and why Frequency Conversion is necessary.

Presently, the Electric Utilities in the United States, Canada and Central America produce power at a frequency of 60Hz. This excludes some of the very old and still in operation Hydro Plants that produce power with at 25HZ.  Most of the other countries throughout the world produce power at a frequency of 50Hz.  Japan is both 50HZ and 60HZ.  South America is split with Brazil and the North Eastern countries being 60HZ.  The rest of the region is operating with 50HZ. 


Small components like computers and small electronics operate with switch mode power supplies.  These operate at both 50HZ and 60HZ and as such, the only item you may need is a plug converter as 50HZ outlets are not the same as 60HZ outlets for the following reason.  As 60Hz and 50Hz operate at different frequency, you do not want to plug equipment into the wrong power source or you run the risk of damaging equipment and or harming yourself.  Once you let the smoke out of the equipment, you cannot put it back in…Larger and 3 phase equipment cannot operate on the wrong frequency as the incorrect frequency can cause damage or premature wear on the equipment. 

50 Hz equipment incorrectly connected to 60 Hz power will operate outside its design criteria.  This will most likely damage the equipment immediately (remember the smoke) or causing it to fail over time from overheating.  Due to the ever growing global economy and worldwide sourcing, equipment must adapt.  This usually results in the need of Frequency Conversion (also called a frequency changer) to change the local utility’s frequency (and sometime its voltage) so it will be compatible with the power requirements of the equipment you are trying to operate (also called the load).


Specific industries have unique frequency requirements and this is based on how they supply power to their equipment.  Aviation and some Weapons systems requires 400Hz.  These systems create 400HZ power internally.  So what happens when the equipment is not operating and providing the internal 400HZ?  A ground power unit, also called a GPU produces 400HZ for this purpose.  Electrical systems used on the ground required the Ground power support.

400Hz is used in many airport and military radar applications. Rail utilize 25, 91.66 or 100Hz to run their signaling systems. Ship yards and boat docks require frequency conversion for shore power.  Ships built in 50HZ countries have electric power systems for 50HZ.  Therefore, the electrical system requires a frequency converter to match the power.  There are also many unique and/or variable frequencies needed in laboratories and testing facilities. 


Some applications are better suited for Rotary Frequency Conversion (also called Motor Generator Sets or Rotary Converters), while others may be more suitable for Static Frequency Conversion (also called Solid State Converters). Each type has its benefits and shortcomings. That is why some companies will build both types of equipment.  By offering both topology’s, the customers can select what they need.  And avoid not dealing with a company that has a vested interest in recommending one version over another.  These result is a more reliable source that will recommend the best possible conversion solution for a given application. Frequency Converters are usually built to any size, which is based on the load 

A Rotary Frequency Converter utilizes a generator to produce a true output sine wave at the desired frequency – much like the power companies. A Static Frequency Converter utilizes a double conversion process with a rectifier that changes the AC input to DC.  After that, the inverter converts it back to an AC output.  And Finally, wave shapes the frequency (and output voltage if necessary) which results in a re-created sine wave. The resulting frequency and/or voltage conversion from either type of unit is suitable for most applications. Price, design life, serviceability, size, and noise are the deciding factors when purchasing a Frequency Converter system.