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The correct use of insulation resistance meter megohmmeter

by:Sure     2021-08-01
Insulation resistance meter Megohmmeter is a commonly used measuring instrument. It is convenient and reliable to measure insulation resistance. It is widely used in many industries. If the megohmmeter is used improperly, it is easy to cause errors, so we need to understand the correct method of use in the process of using, so that we can effectively avoid the generation of errors. Today's insulation resistance meter megohmmeter is a commonly used measuring instrument. It is convenient and reliable to measure insulation resistance, and it is widely used in many industries. If the megohmmeter is used improperly, it is easy to cause errors, so we need to understand the correct method of use in the process of using, so that we can effectively avoid the generation of errors. Today, the editor will give you a specific introduction to the correct use of the insulation resistance meter megohmmeter. I hope it can help you.  When the megohmmeter is working, it generates high voltage by itself, and the measurement object is electrical equipment, so it must be used correctly, otherwise it will cause personal or equipment accidents. Before use, you must first make the following preparations:    (1) Before measurement, the power supply of the equipment under test must be cut off and short-circuited to ground. Never allow the equipment to be charged for measurement to ensure the safety of people and equipment.  (2) For equipment that may induce high voltage, this possibility must be eliminated before measurement can be performed.  (3) The surface of the measured object should be clean to reduce the contact resistance to ensure the accuracy of the measurement result.  (4) Before measuring, check whether the megohmmeter is in normal working condition, mainly check its '0' and '∞' two points. That is, shake the handle to make the motor reach the rated speed. The megohmmeter should point to the '0' position when it is short-circuited, and it should point to the '∞' position when it is open.  (5) When using the megohmmeter, it should be placed in a stable and firm place, and far away from large external current conductors and external magnetic fields.   After the above preparations are done, the measurement can be carried out. When measuring, pay attention to the correct wiring of the megohmmeter, otherwise it will cause unnecessary errors or even errors. There are three terminals of the megohmmeter: one is 'L' which is the wire terminal, one 'E' is the ground terminal, and the other 'G' is the shielding terminal (also called the protection ring). Generally, the measured insulation resistance is connected to Between the 'L' and 'E' ends, but when the surface leakage of the insulator under test is serious, the shield ring of the test object or the part that does not need to be measured must be connected to the 'G' end. In this way, the leakage current flows directly back to the negative terminal of the generator through the shielded terminal 'G' to form a loop, instead of flowing through the measuring mechanism (moving coil) of the megohmmeter. This fundamentally eliminates the effect of surface leakage current. It should be noted that when measuring the insulation resistance between the cable core and the surface, the shield terminal button 'G' must be connected, because when the air humidity is high or the cable is insulated When the surface is not clean, the leakage current on the surface will be very large. In order to prevent the leakage of the measured object from affecting its internal insulation measurement, a metal shielding ring is generally added to the outer surface of the cable. 'End connected. When using a megohmmeter to measure the insulation resistance of electrical equipment, be sure to pay attention to the 'L' and 'E' terminals cannot be reversed. The correct connection method is: 'L' wire terminal button is connected to the conductor of the device under test, 'E' The ground terminal button is grounded to the device shell, and the 'G' shield terminal is connected to the insulated part of the device under test. If the 'L' and 'E' are connected reversely, the leakage current flowing through the insulator and the surface will be collected to the ground through the shell, and flow from the ground to the measuring coil through the 'LThere is a big error. In addition, because the degree of insulation between the internal lead of the 'E' end and the case is lower than that between the 'L' end and the case, when the megohmmeter is used on the ground and the correct wiring method is used, the 'E' end is opposite to the instrument case The insulation resistance between the shell and the ground is equivalent to a short circuit and will not cause errors. When the 'L' and 'E' are connected reversely, the insulation resistance between the 'E' and the ground is connected in parallel with the measured insulation resistance, which will bias the measurement result. If it is small, it will bring greater error to the measurement. Buy resistors on 51gk website www.51gk.com
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