What is AC Generator?
Modern AC sources are, almost exclusively, induction generators, where the principle of work is based on electromagnetic induction. In this case, the electromagnetic current is obtained by rotating the conductors in the magnetic field. Today, almost all alternating current generators are three-phase. This means that in their movable part, which is called a rotor, they have three separate coils, placed between each other at an angle of 120◦, in which three EMC are phase-shifted precisely by 120◦, or in time sequence for a third period.
Coils are usually indicated by the letters R, S and T, each of which defines a single phase. Depending on the binding of these coils, the transmission of electricity from the generator to the consumer is carried out with 4 or with 3 conductors. If at the beginnings of all the coils are bound at one point (the so-called zero point), then we are talking about star connection. In that case, the other ends of each coil, are connected with one phase (or line) conductor, and one additional conductor from the zero point – the zero conductor, and the transmission is carried out with 4 conductors. If the coils are bound so that one end of one conductor is connected to the beginning of the next, and so to the end, then such a connection is called a triangle connection. For a star connection, the voltages between the individual phase conductors and the zero conductors are called phase voltages. All phase voltages of evenly loaded network are the same and have an effective value of 220 V: On the other hand, in case of a triangular connection, the voltages between the individual phase conductors are called inter-phase or line voltages. Inter-phase voltages are URS , UST and URT and they are √3 times the phase voltage. Their effective value is √3 · 220 V ≈ 380 V:
Comments
Post a Comment