What Is 3 Phase 400Hz?

Delivery

• Where 400Hz 3-phase electricity supply is available, it is typically delivered via a distinctive 5-pin connector, with a larger earth pin and four smaller pins. One of the smaller pins carries a common neutral, and the remaining three carry live voltages at different phases.

Voltage

• The voltage in an alternating current system can be described as a sinusoidal waveform ̵1; a waveform of single constant frequency and amplitude that completes one oscillation in 360 degrees. A 3-phase system consists of three separate phase conductors, or wires, in which the voltages are 120 degrees out of phase with each other. In other words, the voltage in the first phase conductor is at 0 degrees in its cycle when the voltages in the second and third conductors are at 120 degrees and 240 degrees, respectively.

Frequency

• The term "400Hz" means 400 hertz, or cycles per second, and refers to the frequency at which the sinusoidal wave repeats itself. Most AC power is generated at a frequency of 50Hz or 60Hz, but some high-performance applications found on aircraft and spacecraft, for example, use a frequency of 400Hz to achieve lighter, higher speed motors.

Advantages

• The advantages of 3-phase 400Hz over other forms of electricity supply include that power is supplied by three wires carrying the same current rather than one large single-phase wire that is difficult to handle. This allows smaller, lighter wires to be used, which can be practical, for example, in aerospace applications, where weight is all-important. According to the Historic Naval Ships Association, the 3-phase 400Hz system used by naval aircraft not only allows smaller wiring but also a lighter AC generator and control and protection components.

Electricity Distribution

• Producing 3-phase current in a single generator is more efficient than using single-phase generators. Furthermore, 3-phase 400Hz electricity supply produces a smooth waveform capable of transmitting high power, which is one reason why it is also used in large-scale electricity distribution systems such as the National Grid.