How to check the air switch with multimeter
Let's take this 3P open circuit as an example. First, let's turn the open circuit to the open position, and use a multimeter to measure whether the three circuits are connected. It is good if they are not connected. Then push it to the open position and measure whether it is good or not.
Because of the low accuracy of ordinary multimeter, it can only be used as an auxiliary appliance at ordinary times. Can't be used as a device to issue specific data. Therefore, there is a certain error in detecting the quality of air switch with multimeter. However, there is no special instrument in ordinary families, and it is also good to have a multimeter to measure voltage, current or resistance.
The air switch has two automatic protection functions: overload protection and short circuit protection. In addition, it can also connect the breaking circuit to isolate the power supply. The functions of overload protection and short-circuit protection can't be checked by multimeter, and a large current generator is used to detect overload performance in the laboratory. Short-circuit performance needs transformer, short-circuit impedance and data acquisition system to complete the detection. But at home, you can use a multimeter to check whether the contact is consistent with the position indicated by the handle. Sometimes the air switch is energized for a long time, or the contact will be welded after a fault occurs. When welding, even if the handle is in the off position, one or several poles of the contact will be in the on state. At this time, the state of the contact can be checked with the multimeter resistor.
In the same way, if the mechanism fails or a large short-circuit current is broken, the contact may not be able to connect the circuit. When we turn the handle of the air switch to the closed position and there is no electricity on the load side of the switch. You can also use a multimeter to measure the voltage on the load side, or measure the resistance after disassembly. To determine whether the contact is connected to the circuit.
