How to use a multimeter to check whether the air switch is in good or bad condition
We can only use a multimeter to measure the air switch simply to see if it is turning on and off well.
We take this 3P air switch as an example, we first hit the air switch to the disconnect position, using the multimeter resistance file to measure whether the three circuits are connected, not pass is good. Then push it to the open position, measure the pass-through, pass is good not pass is bad.
Due to the low precision of the ordinary multimeter, usually can only be used as an auxiliary tool. Can not be used as equipment to produce specific data. So using a multimeter to detect the good and bad air switches also have a certain degree of error. However, ordinary families do not have a special instrument, a multimeter to measure the voltage, current or resistance is also very good.
Air switch has overload protection and short circuit protection two automatic protection function. In addition, it can also connect and break the circuit, play the role of isolation of the power supply. Overload protection and short-circuit protection function we use a multimeter can not check, in the laboratory test overload performance using high-current generating device. Short-circuit performance requires the use of transformers, short-circuit impedance, data acquisition system to complete the test. But at home you can use a multimeter to check whether its contacts are consistent with the handle indication position. Sometimes the air switch is energized for a long time, or after a fault, the contacts will melt and weld, and when melting and welding, even if the handle is in the breaking position, the contacts will have one pole or several poles in the on state, and then the resistance of the multimeter can be used to check the state of the contacts.
By the same token, if the mechanism fails or after breaking a large short-circuit current, the contacts may not be able to connect the circuit. We hit the handle of the air switch to the closed position when there is no power on the load side of the switch. You can also use a multimeter to measure the voltage on the load side, or remove it and measure the resistance. To determine whether the contacts have turned on the circuit.
