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Gibbons jargon buster #15: What is frequency?

Here’s the latest straight-talking blog clearing up terminology from our industry. Today we ask “what is frequency?” and reveal how it affects electric motor selection.

Frequency is the rate at which alternating current (AC) makes a complete cycle, and it is expressed in cycles per second or Hertz (Hz). In the case of electric motors, the frequency of the AC current is one of the factors that determines speed.

In the early days of electrification, there were many different frequencies used across the world and even within countries. In fact, in 1918 there were 10 different frequencies used in London alone. Globally, several frequencies between 16 2/3 Hz and 133 1/3 Hz were used until standardisation in the early 20th century allowed electrical equipment to be traded internationally. The majority of countries now use 50 Hz power, although in the US, Canada and parts of South America the standard is 60 Hz.

Like any other electric appliances, electric motors are manufactured specifically to be powered by a certain frequency. However, with the use of a variable-speed drive (also known as a variable-frequency drive or inverter), input frequency can be adjusted to control motor speed.

We hope that’s cleared it up, and if you’d like some more information on Gibbons’ range of electric motors and ABB variable-speed drives, give us a call on 01621 868138 or email

Variable-Speed Drives, Electric Motors

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