The alternator converts rotating energy (from the engine) into electric energy. Depending on the load, you need a single-phase or a three-phase generating set. Three-phase generating sets also have single-phase sockets. For the conversion we mainly use two kinds of plugs.
Single-phase plugs are used for household appliances and other apparatus. These plugs vary from one country to another.

Three-phase plugs mostly are red and have 4 (3 phase wires + earth wire) or 5 connection points (3 phase wires + neutral + earth wire). These are connected in Y (star) or in Δ (delta).


In industry, plugs with specific colors are used. In Europe, they are also called CEE-plugs.


Single-phase connection (1*230V)

Only one winding (coil) is used.

Three-phase connection (3*400V)

Here, we use three windings (coils) that can be connected in two different ways.
A three-phase generating set can be connected in Y (star) or in Δ (delta). The difference lies in the connection of the windings. If the generating set is connected in Y, there are two possible voltages: phase voltage (VP = 230V) and line voltage (VL = 400V). We can say that VL = √3*VP en IP = IP. If the generating set is connected in delta, the line voltage VL equals the phase voltage VP and IL = √3*IP. ‘IL’ stands for line current and ‘IP’ stands for phase current.
Besides, the star configuration has 4 wires (3 phase wires and 1 neutral wire starting from the star point), while the delta configuration has no neutral wire.

Attention: If you use one of the single-phase sockets of a three-phase generating set, you may only charge the generating set with maximum 1/3 of the total power, unless stated otherwise.

Ssingle-phase ≈ 1/3*Sthree-phase or Psingle-phase ≈ 1/3*Pthree-phase
Example: if a three-phase generating set has a power of 6kVA, one winding can produce 2kVA.



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