Supply voltage frequency

The mains voltage is an alternating voltage. It means that the value is alternately positive and negative. The usual waveform of alternating current is a sine wave (Fig. 1).

A single period of the alternating voltage waveform. The period lasts 20 milliseconds, which means that in one second it is repeated 50 times, i.e. its frequency is 50 Hz (Fig. 2). In other words, 1 hertz corresponds to 1 cycle per second.

In Europe any many non-European countries, the mains voltage is 50 Hz. There are numerous exceptions, e.g. in most North and Central American countries (USA, Canada, Mexico etc.) the mains voltage is 110 V at 60 Hz. A noteworthy fact is that in the eastern Japan, the mains frequency is 50 Hz and in its western part it is 60 Hz, and both systems are connected via special converters.

Most power supplies offered by Delta can operate at 50-60 Hz, and for most users, the mains frequency is not an issue. It is worth remembering that an asynchronous motor (squirrel-cage motor) speed can easily be adjusted by changing the frequency. Change in mains frequency also affects the velocity of the magnetic field rotation which, as a result, reduces or increases the rotor speed - a part that rotates inside the motor. This function is provided by the inverters. Those devices gain popularity in many industries since they provide highly efficient speed adjustment.