How to use a clamp ammeter correctly? What precautions should be taken when using?
1. Before measurement, the rubber insulation of the clamp iron core should be checked for completeness and undamaged condition. The jaws should be clean, rust free, and have no obvious gaps when closed.
2. When measuring, the magnitude of the measured current should be estimated first and an appropriate range should be selected. If it is impossible to estimate, you can first choose a larger range, then gradually reduce it and switch to the appropriate gear. When switching the range gear, it must be done without being charged or with the jaws open to avoid damaging the instrument.
3. When measuring, the measured wire should be placed in the middle of the clamp as much as possible. If there is any noise on the joint surface of the clamp, it should be opened and closed again. If there is still noise, the joint surface should be treated to make the reading accurate. Additionally, it is not allowed to clamp two wires simultaneously.
4. When measuring currents below 5A, in order to obtain more accurate readings, if conditions permit, the wire can be wound a few more times and placed in the clamp for measurement. The actual current value should be the instrument reading divided by the number of wires placed in the clamp.
5. Before and after each measurement, the switch for adjusting the current range should be placed in the highest gear to avoid damaging the instrument during the next use due to measurement without selecting the range.
matters needing attention
When using a clamp ammeter to detect current, be sure to clip in a wire (wire) being tested. If two parallel lines are inserted, the current cannot be detected.
In addition, when using the center (iron core) of the clamp ammeter for detection, the detection error is small. When checking the power consumption of household appliances, using a circuit separator is more convenient. Some circuit separators can amplify the detection current by 10 times, so currents below 1A can be amplified before detection.
When using a DC clamp ammeter to detect DC current (DCA), if the current direction is opposite, it displays a negative number. This function can be used to detect whether the car's battery is in a charging or discharging state.
True RMS detection
The clamp ammeter with average value method detects the average value of the sine wave through AC detection, and displays the value after amplification by 1.11 times (sine wave AC) as the effective value. Waveforms other than sine waves with different waveform rates and skewed waves are also displayed after being magnified by 1.11 times, resulting in indication errors. Therefore, when detecting waveforms and distortion outside of sine waves, please choose a clamp ammeter that can directly test the true effective value.
Leakage detection
Leakage detection is different from typical current detection, where two (single-phase 2-wire) or three (single-phase 3-wire, three-phase 3-wire) wires need to be clamped together. It is also possible to clamp the grounding wire for testing. The insulation management method for detecting leakage current in low-voltage circuits has become the primary means of judgment. Since its confirmation by the 1997 revision of electrical equipment technical standards, leakage current clamp meters have gradually been used for detection in buildings and factories that cannot be powered off.
