News
① When measuring the insulation resistance of equipment, the power supply must be cut off first. Equipment with large capacitance (such as capacitors, transformers, motors, and cable lines) must be discharged first;
② The megohmmeter should be placed in a horizontal position. Before wiring, first shake the megohmmeter to see if the pointer is at "∞", and then short circuit the two terminals (L) and (E). Slowly shake the megohmmeter to see if the pointer is at "zero". For semiconductor type megohmmeters, short circuit calibration should not be used;
③ The lead wire of the megohmmeter should be multi-stranded flexible wire and should have good insulation;
④ Double circuit overhead lines and busbars that cannot be completely powered off are prohibited from being measured when the induced voltage of the tested circuit exceeds 12 volts, or when thunderstorms occur on the overhead lines and electrical equipment connected to the overhead lines;
⑤ When measuring capacitors, cables, large capacity transformers, and motors, there should be a certain amount of charging time. The larger the capacitance, the longer the charging time. Generally, the reading after one minute of rotation of the megohmmeter shall prevail;
⑥ When shaking insulation, the megohmmeter should be kept at the rated speed. Generally, it is 120 revolutions per minute. When the capacitance of the measured object is large, in order to avoid pointer oscillation, the speed can be appropriately increased (such as 130 revolutions per minute);
⑦ The surface of the tested object should be wiped clean and free of dirt to avoid affecting the accuracy of the measurement.
