1. First, choose the correct voltage level for the clamp-type ammeter, then examine the device to see whether it looks okay, if there is damage, if the pointer swings freely, and if the jaw is rusted. To choose the meter's range, calculate the rated current depending on the motor power.
2. Before using the clamp ammeter, you should read the manual carefully to find out whether it is an AC or AC/DC clamp meter.
3. Due to the clamp-type ammeter's poor precision, the following technique can be used to measure small currents: first, wind the circuit under test's wire several times before placing it in the clamp-type meter's jaws. The clamp meter's display of the current value currently does not correspond to the measurement being made. The clamp meter value should be divided by the wire's number of spins to determine the actual current.
4. When measuring, the clamp meter's jaws should be shut tightly. The jaws can be opened again and closed once more if there is any noise after shutting. If the noise cannot be reduced, see if the magnetic circuit's junction surfaces are smooth and clean. Clear it off.
5. Only one phase wire's current can be measured at a time using the clamp meter. Multi-phase wires cannot be clamped into the clamp window for measurement; the measured wire must be put in the window's center.
6. The voltage of the circuit under test cannot exceed the value indicated on the clamp meter, otherwise it is easy to cause a grounding accident or risk of electric shock.
7. Measure the working current of the squirrel asynchronous motor in operation. According to the size of the current, it can be checked and judged whether the working condition of the motor is normal, so as to ensure the safe operation of the motor and prolong the service life.
8. When measuring, it can be done in three steps or once for each phase. The reading on the meter ought to be zero at this point (because the three-phase current phasor sum is zero). The meter should read 0 when two phase wires are in the jaws. The third phase's current value is seen in the value shown above. By measuring the current in each phase, it is possible to determine whether the motor is overloaded (the measured current exceeds the rated current value), the internal motor, or the power supply (the component that transforms other forms of energy into electrical energy) is malfunctioning. This is done by determining whether the three-phase current imbalance is above the threshold of 10%.
