Method for Finding Electrical Control Circuit Faults with a Multimeter
1、 Voltage measurement method.
Firstly, power on the control circuit and adjust the multimeter gear switch to the AC voltage range of 750V. According to the circuit schematic, one probe of the multimeter is kept at line 9, and the other probe is used to measure lines 8-7-6-5-4-3. Without closing the switch, the two probes are in phase and the voltage is 0V. When measuring line 2-1, the two probes are in different phases and the voltage is around 380V. This is the normal state of the circuit, The voltage value of which line and point does not match the circuit schematic, so in most cases, the point where the voltage value is incorrect is the fault point!
2、 Resistance measurement method.
Firstly, the circuit needs to be powered off, verified, and confirmed to be dead. After confirming that there is no power, set the multimeter gear switch to the beep or resistance position, and place the two probes of the multimeter at Line 1 and Line 9 respectively. Under normal circumstances, press the SB1 or SB2 buttons respectively, or directly press the two AC contactor springs manually (i.e. manually close the normally open points of KM1 or KM2). At this time, 1-9 is connected, and the circuit is open, The multimeter will have a corresponding coil resistance value. If there is no resistance value, it proves that the circuit is not working. It is necessary to compare the circuit schematic to measure and analyze the on/off point by point, and the measurement method is similar to the voltage.
3、 The resistance measurement method and voltage measurement method of a multimeter are the two most commonly used methods in circuit fault diagnosis. It can be said that each has its own advantages and convenience, and the key is which method you are accustomed to using. Use the multimeter to measure using the method you are most familiar with.
Method for Finding Electrical Control Circuit Faults with a Multimeter
There are generally voltage method and resistance method for finding circuit faults. The voltage method is to use voltage measurement to detect fault points, while the resistance method is to use resistance measurement to find faults. They each have their own advantages. If you are not familiar with the circuit, we recommend using the resistance method to determine the fault, which is relatively safer.
