How to use a digital multimeter to check if the circuit is grounded
Set the digital multimeter to a resistance range of 20K or higher and measure the insulation between phases separately.
Measure the grounding of the measurement line, which measures the outer shell of the electrical equipment. If the grounding of the line touches the outer shell of the equipment, the resistance value is usually several hundred ohms or more, or even zero.
That's how I measure the crane control line.
If measuring the resistance of the circuit to the ground simply, a multimeter is not easy to measure. It is recommended to use an ohmmeter for measurement.
Method 1 for determining whether the ground wire socket is grounded:
1. First, separate the live line and neutral line. Ground wire: Set the multimeter to the AC voltage range, and the range should be higher than 220V. Insert the red probe into the voltage port, do not insert the black probe, and then insert the red probe into one of the sockets to observe the reading. The line with the highest reading is the live line, the line with the lowest reading is the neutral line, and the line with almost no movement is the ground line. If two readings are small and one reading is large, it means that the ground wire is not grounded and the ground wire is also connected to the neutral wire. The second step behind does not need to be measured.
2. Measure the ground wire: After separating the live wire, neutral wire, and ground wire, the multimeter remains in the previous gear (AC gear above 220V), with the red and black probes inserted into the voltage and COM holes, respectively. Use two probes to measure the voltage between the live wire and the neutral wire, as well as the voltage between the live wire and the ground wire. If these two voltage values are basically the same, it indicates that the ground wire is grounded; If the voltage value between the live wire and the ground wire is basically zero or particularly small, it indicates that the ground wire is not grounded.
Method 2:
1. Set the digital multimeter to a resistance range of 20K or higher and measure the insulation between phases separately.
2. Measure the grounding of the measurement line, which measures the outer shell of the electrical equipment. If the grounding of the line touches the outer shell of the equipment, the resistance value is usually several hundred ohms or more, or even zero.
3. This is how the control line of the crane is measured.
4. If measuring the resistance of the circuit to the ground simply, a multimeter is not easy to measure. It is recommended to use an ohmmeter for measurement.
