Clamp ammeter for measuring three-phase current
1. Firstly, select the voltage level of the clamp type ammeter correctly, check whether its appearance insulation is good, whether there is any damage, whether the pointer swings flexibly, and whether the clamp mouth is corroded. Estimate the rated current based on the motor power to select the range of the meter.
2. Before using a clamp ammeter, carefully read the manual to determine whether it is an AC or AC/DC dual-purpose clamp ammeter.
3. Due to the low accuracy of the clamp ammeter itself, the following method can be used to measure small currents: first, wrap the wires of the tested circuit a few times, and then place them into the clamp of the clamp ammeter for measurement. At this point, the current value indicated by the clamp meter is not the actual value being measured. The actual current should be the reading of the clamp meter divided by the number of turns the wire is wound.
4. When measuring, the jaws of the clamp type watch should be tightly closed. If there is any noise after closing, the jaws can be opened and reset once. If the noise still cannot be eliminated, the joint surfaces on the magnetic circuit should be checked for smoothness. If there is dust, it should be wiped clean.
5. The clamp meter can only measure the current of one phase wire at a time. The measured wire should be placed in the center of the clamp window, and multiple phase wires cannot be clamped into the window for measurement.
6. The voltage of the tested circuit should not exceed the value indicated on the clamp meter, otherwise it may cause grounding accidents or electric shock hazards.
7. Measure the working current of the cage type asynchronous motor during operation. Based on the current level, it is possible to check and determine whether the motor is working properly to ensure safe operation and extend its service life.
8. When measuring, it is possible to measure once in each phase or once in three phases. At this time, the number on the meter should be zero (because the sum of three-phase current phasors is zero). When there are two phase lines in the clamp, the displayed value on the meter is the current value of the third phase. By measuring the current of each phase, it can be determined whether the motor is overloaded (the measured current exceeds the rated current value), and whether there is a problem with the power supply voltage inside the motor or (a device that converts other forms of energy into electricity is called a power supply), that is, whether the three-phase current imbalance exceeds the limit of 10%.
9. Before measuring with a clamp meter, the magnitude of the measured current should be estimated before deciding which range to use. If it is impossible to estimate, you can first use the maximum range range range and then adjust it appropriately to obtain an accurate reading. Low current range cannot be used to measure high current. To prevent damage to the instrument.
