1. Before measuring, keep the megohmmeter in a horizontal position, hold the watch body with your left hand, and shake the handle of the megohmmeter with your right hand. The rotation speed is about 120r / min. The pointer should point to infinity (∞), otherwise the megohmmeter is faulty.
2. Before the measurement, the power supply of the electrical appliance and the circuit under test should be cut off, and the related components should be temporarily grounded to ensure the safety of the person and the megohmmeter and the accurate measurement results.
3. Must be correctly wired during measurement. The megohmmeter has 3 terminals (L, E, G). When measuring the resistance of the loop to earth, the L end is connected to the bare conductor of the loop, and the E end is connected to the ground wire or metal shell; when measuring the insulation resistance of the loop, the first and tail ends of the loop are connected to L and E respectively; the insulation of the measurement cable In the case of resistance, in order to prevent the leakage current of the cable surface from affecting the measurement accuracy, the shield of the cable should be connected to the G terminal.
4. The insulation of the measuring cord drawn from the terminal of the megohmmeter should be good, and an appropriate distance should be maintained between the two conductors and between the conductor and the ground, so as not to affect the measurement accuracy.
5. When shaking the megohmmeter, do not touch the terminals of the megohmmeter and the circuit under test to prevent electric shock.
6. After shaking the megohmmeter, the terminals should not be shorted to avoid damage.
Fu Shun Dewen Xu Jingxiang Excerpts II. Usage and requirements of electronic megohmmeter
1. Check whether the meter is normal before measurement
A. Start-up inspection display, normal display OL;
B. See if the gear can be converted normally (generally there is gear selection, that is, voltage selection)
C. Press the test button to check whether there is corresponding voltage output, method:
Use a common multimeter to select the highest DC voltage, then insert the test lead into the output terminal of the megohmmeter, press the test key of the megohmmeter to observe whether the corresponding voltage value is displayed on the multimeter;
2. Enter the field measurement after the pre-measurement preparation work is completed
A. If OL is displayed during measurement, it is possible that the measured resistance exceeds the measurement range of the instrument and the gear can be switched (MΩ, GΩ, according to the function configuration of the instrument itself);
B. The instrument cannot be tested without voltage output, and can be tested according to the relevant introduction in the first paragraph;
3. Electronic megohmmeters mostly use voltage multiplier circuits, and the power supply current required by the 5th battery or 9 volt battery is relatively large, so they must be shut down when not in use (even if the automatic shutdown function is recommended, manual shutdown is recommended. );
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