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# 8 tips for air switch rated current selection

By：Nader Updated：September 09,2020 11:32AM

The general selection principle of automatic air switch is:

(1) Determine the type and protection form of the circuit breaker according to the protection requirements of the line-determine the choice of frame type, device type or current limiting type.

(2) The rated voltage of the automatic air switch ≥ the rated voltage of the line.

(3) The rated current of the automatic air switch ≥ the line calculated load current.

(4) The setting current of the thermal release = the rated current of the controlled load.

(5) The instantaneous tripping setting current of the electromagnetic tripping device ≥ the peak current when the load circuit is working normally.

(6) The rated voltage of the under-voltage release of the air switch = the rated voltage of the line.

(7) The protection characteristics of the upper and lower circuit breakers in the distribution line should be coordinated, and the lower protection characteristics should be located below the upper protection characteristics and do not intersect.

(8) The long-time tripping current of the circuit breaker should be less than the allowable continuous current of the wire.

The air switch leakage and short circuit protection trip current selection of household air conditioners can be calculated according to the air conditioner power and supply voltage (220V single-phase power or 380V three-phase power), and then add a certain safety margin current. It is the air switch leakage and short circuit protection trip current. Example: If your current air conditioner power is 3P, 220V voltage power supply, the loop current of the air conditioner normally working is: 735W*3/220V=10A (1P is equal to 735W), plus a certain safety margin current, Then the air conditioner leakage and short circuit protection trip current can be selected as an air switch with a rated current of 16A or 20A. If the air conditioner power is 3P, 380V voltage power supply, the normal working loop current of the air conditioner is: 735W*3/380V=5.8A, plus a certain safety margin current, then the air conditioner leakage and short circuit protection trip current should be rated An air switch with a current of 16A is sufficient. At this time, an air switch with a rated current of 20A is too large. Your air conditioner can refer to the above example for calculation and select the air switch with the corresponding rated current.