Why 3-phase voltage is 440V instead of 660V?

Answer 1

Three-phase is transmitted at many different voltages but a 440 v 3-ph supply has 440 v between the phase wires by convention and is used in supplying power to groups of houses or small businesses.

The voltage between any of the phases and neutral is 440/sqrt(3) which equals 254 v.

A typical 440 v 3-ph transformer might be able to supply 700 amps, which gives 180 kVA, enough for about 90 houses.

Answer 2

You would use 440 v 3-phase in a large house or business where the need for electric power is more than can be supplied by a normal single-phase circuit.

A very large business needing more than about 700 kVA might use 11 kV 3-phase.
A 3-phase supply allows more power to be used than with a single-phase supply. 3-phase is the usual way of transmitting electric power efficiently. For domestic supplies a street might have a 3-phase supply running along it with each property using one of the three phases.

Answer 3

A standard voltage for 3-phase suppies in Europe is 440 v. That gives a line-to-neutral voltage of 254 v. 690 v is not used, mainly because it is higher than is considered satisfactory because it is more dangerous.

Answer 4

The standard voltage for 3-phase power systems is usually set to 440V to balance the need for efficient power distribution with equipment safety requirements. This voltage level allows for adequate power delivery while also helping to minimize risks associated with higher voltages, such as insulation breakdown and electrical accidents.

Answer 5

at generation one phase is positive, one phase is negative and another is zero simeltaneously

Answer 6

Because 3 phase voltage is not algebraic sum it is the vectorial sum. Vijaye Raj A.I.E.M.D