How to Measure Line Current Using a Clamp Meter
A clamp meter is a meter used to measure the magnitude of the current in a running electrical circuit, which can measure the current without interruption of power supply. The clamp meter is actually a current transformer. The stuck wire is equivalent to the primary coil of the transformer. When there is current in the wire, a magnetic flux will be generated in the iron core of the meter, and then in the secondary coil of the meter. The current is induced, which is equal to the current in the primary coil multiplied by the number of turns of the primary coil (that is, a wire, so it is one turn) divided by the number of turns of the secondary coil, and then according to this relationship, the wire can be converted in the current.
How to Measure Current Using a Clamp Meter
1. The clamp meter should be zeroed mechanically before measurement;
2. Select the appropriate clamp meter range: adjust from large to small range or look at the nameplate value estimation;
3. When the minimum range of the clamp meter is used to measure, and the reading is not obvious, the measured wire can be wound around a few turns, and the number of turns should be based on the number of turns in the center of the jaw, then the reading = indicated value × range / full Offset × number of turns;
4. When measuring, the wire under test should be in the center of the jaws, and the jaws should be closed tightly to reduce errors;
5. After the measurement is completed, the switch of the clamp meter should be placed in the range.
In layman's terms, the clamp meter has digital display and pointer display. When measuring, roughly estimate the approximate range of the measured current, pay attention to the selection of the clamp meter range, and try to choose the appropriate range to reduce errors. In addition, try to clamp the wire in the middle of the jaws of the clamp meter. If the measured current is too small, you can wind the wire into multiple wires, and then divide the measured value by the number of wires. Also, be careful not to measure the bare wire to avoid electric shock. Danger.
If it is a clamp meter that can measure voltage and other functions, unplug the test leads when measuring current. Furthermore, in a three-phase load, clamping one wire in the jaws measures the current of the own wire, and clamping two wires measures the current of the third wire.
Matters needing attention when clamp meter is measuring current
1. The voltage of the line under test should be lower than the rated voltage of the clamp meter;
2. When measuring the current of the high-voltage line, wear insulating gloves, wear insulating shoes, and stand on the insulating mat;
3. The jaws should be closed tightly and the range cannot be changed while the power is on;
4. Before measuring the resistance, the circuit to be tested must be completely discharged and completely isolated from the power circuit;
5. If the test pen or power adapter is damaged and needs to be replaced, it must be replaced with a test pen and power adapter of the same model and the same electrical specification;
6. Do not use the instrument when the battery indicator indicates that the power is exhausted. If the instrument will not be used for a long time, please take out the battery and store it;
7. Do not store or use the clamp meter in high temperature, high humidity, flammable, explosive and strong electromagnetic field environment;
8. Please use a damp cloth or detergent to clean the clamp meter shell, do not use abrasives or solvents;
9. When the instrument is wet, please dry it before storing it.
