The single control line is 1 line, generally1p. This is a small short circuit breaker. The second stage below 220V is used for 220v, namely 1 control fire line and 1 zero line. Bipolar is rarely used in power equipment, because the equipment is charged due to primary open circuit, lack of phase or eccentricity, unless it is used in a socket.

Generally, it becomes 2P3 level, which is generally used for 380V, that is, three control fire lines 1 zero line, which is generally 3P.

The short circuit breaker used in power equipment is also called three-phase air switch, and there are other short circuits: unipolar leakage protection short circuit breaker, bipolar leakage protection short circuit breaker and tripolar leakage protection short circuit breaker. You can connect several incoming wires, that is, several poles.