How to maintain a clamp watch
A clamp type ammeter is an instrument used to measure the current level of an operating electrical circuit, which can directly measure the working current of equipment in operation without disconnecting the power supply and circuit. In addition, it can also measure AC and DC voltage, resistance, and pass tests.
There are many models of clamp type ammeters, but their appearance is basically similar, as shown in Figure 9-13. The usage method is as follows:
(1) Precautions for using clamp type ammeters
① Before measurement, the initial measurement current should be estimated and an appropriate range should be selected.
② The measured current carrying wire should be placed in the center position of the clamp during measurement to avoid errors. For the measurement of wires with less current, in order to improve accuracy, if conditions permit, the measured wire can also be wound a few more turns and then placed in the clamp for measurement. The actual current value is equal to the reading of the instrument divided by the number of wire turns.
③ If there is noise during the measurement process, it is due to poor contact between the jaws and the wire. The jaws can be reopened and closed again. If the noise still exists, the jaws can be cleaned with gasoline before measurement.
(2) Measurement operation method
① AC power measurement. Turn the switch to position ACA1000A. Keep the switch in a relaxed state. Press the trigger to open the jaws, clamp a wire, and read the value. If the reading is less than 200A, the switch should be turned to ACA200A to improve the accuracy of the reading.
② Measurement of AC and DC voltage. When measuring DC voltage, turn the switch to the DCV1000 position. When measuring AC voltage, turn the switch to the ACV750V position to keep the switch in a relaxed state. Connect the red lead to the "V Ω" terminal and the black lead to the "COM" terminal, and then connect the red and black lead in parallel to the circuit under test. The value read is the actual voltage of the circuit.
③ Measurement of resistance. Turn the switch to the appropriate resistance range. Keep the switch in a relaxed state. Press the "V Ω" end for the red lead, and connect the "COM" end for the black lead. Connect the red and black probes to both ends of the measured resistance, and the read value will be the actual resistance value of the measured resistance.
Attention: When measuring the online resistance, the circuit should be powered off and the capacitor connected to the resistance should be discharged.
④ On/off test. Turn the switch to the 200 Ω position, connect the red lead to the "V Ω" end and the black lead to the "COM" end. If the buzzer inside the meter sounds, it indicates that the resistance between the red and black probes is less than 50 ± 2.5 Ω.
