The 2 most practical ways to use multimeters to troubleshoot circuit faults
1. Voltage measurement method.
First, energize the control loop, and adjust the multimeter's gear switch to the AC voltage range of 750V. According to the circuit schematic diagram, one test lead of the multimeter is kept at line 9, and the other test lead measures 8-7-6-5-4- respectively. On line 3, when the switch is not closed, the two test leads are in phase and the voltage is 0V. When measuring line 2-1, the two test leads are out of phase and the voltage is about 380V. This is the normal state of the circuit. If during the measurement , the voltage value of which line and point does not match the circuit schematic diagram, then in most cases, the point with the wrong voltage value is the fault point!
2. Resistance measurement method.
First, you need to power off the circuit, check the power, and after confirming that there is no power, adjust the multimeter switch to the buzzer or resistance position, and place the two test leads of the multimeter at line 1 and line 9 respectively: Under normal circumstances, respectively Press the SB1 or SB2 button, or manually press the two AC contactor springs respectively (that is, manually close the normally open point of KM1 or KM2). At this time, 1-9 are conductive, the circuit is open, and the multimeter will have The corresponding coil resistance. If there is no resistance value, it proves that the circuit is blocked. It is necessary to measure and analyze the continuity point by point according to the circuit schematic diagram. The measurement method is similar to that of voltage.
3. The multimeter's resistance measurement method and voltage measurement method are the two most commonly used methods in circuit troubleshooting. It can be said that each has its own benefits and conveniences. The key is which one you habitually use. Use a multimeter to measure using the method you are most familiar with.
