Measure the leakage current of the switchgear using a clamp meter
The steps for measuring the leakage current of the
switchgear with a clamp meter are as follows:
1. **Preparation Work**
- Check whether the appearance of the clamp meter is damaged and whether the display screen shows normally.
- Confirm whether the range of the clamp meter is suitable for measuring the leakage current of the switchgear.
Generally, select an AC current range with a relatively large range, such as 200A or higher.
- Ensure that the operator wears insulating gloves and insulating shoes to guarantee personal safety.
2. **Measurement Steps**
- Open the door of the switchgear and find the circuit line that needs to be measured. For a switchgear with a
three-phase four-wire system, measure the three phase wires and one neutral wire separately.
- Open the jaws of the clamp meter and put it over the measured line. Note that the jaws should be completely
closed without any gaps to ensure the accuracy of the measurement.
- Read the current value displayed on the display screen of the clamp meter. If the measured value is zero or very
small, it indicates that there is no leakage current in this line; if the measured value is obviously not zero and exceeds
the normal operating current range, there may be a leakage situation.
- To ensure the accuracy of the measurement, you can measure the same line multiple times at different positions,
take the average value or observe the change of the measured values.
- After the measurement is completed, close the door of the switchgear and store the clamp meter properly.
3. **Precautions**
- Keep focused during the measurement to avoid electric shock or other safety accidents caused by misoperation.
- Do not open the door of the switchgear for measurement when it is in operation, unless necessary safety measures
are taken, such as power outage and voltage testing.
- If a leakage phenomenon is found in the switchgear, stop its operation in a timely manner, carry out maintenance,
and resume operation after troubleshooting.
- The clamp meter can only measure AC current. For the measurement of DC leakage current, a special DC clamp meter
or other measuring tools are required.
It should be noted that the clamp meter is mainly used to measure the current in the line, and the detection of leakage
current is only an indirect method. If you want to accurately measure the leakage current of the switchgear, special leakage
current testers and other equipment are still needed.