Is it necessary to use a clamp watch when installing a motor?
A clamp type ammeter is used to measure the actual current of a phase line, as it is equivalent to a CT with an open circuit in the primary winding. The detected current will be reflected in the second display, independent of the connection of the three-phase motor.
The first step is to measure the phase separately, which can directly measure the phase voltage on the secondary side of the voltage transformer (as described above) or directly measure the phase voltage (at the input end of the clamp meter). However, it is necessary to insert the probe and select the appropriate measurement range. Its "bayonet" can only be a specialized clamp type meter for measuring AC current. Keep the pointer on the right side and use the same method as a regular multimeter to gradually change from high to low gear when the voltage level is unknown;
The second step is to measure the voltage in parallel with the probe. The clamp meter cannot directly "clamp" the voltage with its accompanying multimeter, and the conversion switch should be adjusted to the appropriate range.
The use of digital clamp watches
1. Mechanical zero adjustment is required before measurement.
2. Choose an appropriate range, first select a large range, then select a small range or estimate the nameplate value.
When using the minimum range measurement, when the reading is not obvious, the measured wire can be wound several times. The number of turns should be based on the number of turns in the center of the jaw, and the reading=the indicated value × Range/full deviation × Number of turns.
After measurement, place the transfer switch in the maximum range.
When measuring, the measured wire should be in the center of the clamp, and the clamp should be tightly closed to reduce errors.
Precautions for digital pliers watches
The voltage of the tested circuit should be lower than the rated voltage of the clamp meter.
When measuring the current of high-voltage lines, wear insulated gloves, insulated shoes, and stand on an insulated pad.
3. The jaws should be tightly closed and the range cannot be changed by electricity.
Using a clamp ammeter to measure the current of a single winding of a motor is phase current, but it may cause trouble in actual measurement, or all three pairs of winding wires may be externally connected. The current on the power line is always the line current; Calculating the power of an electric motor is both difficult and impractical. Power factor is an uncertain factor, unless you connect a power factor meter, but you should be aware that power factor can vary depending on the load.
