Standard for measuring insulation resistance of control cabinet
Sign posts table for a total of three: a "L" is the end of the line, a "E" is to end, a "G" end shield (also called protection rings), generally measured insulation resistance are connected between "L" and "E" end, but when the measured insulator leakage serious, shielding ring must be measured or not should be measured in partially connected with "G". In this way, the leakage current flows directly through the shield terminal "G" to the negative end of the generator to form a loop instead of the measuring mechanism (moving coil) flowing through the ohmmeter. This will fundamentally eliminate the influence of surface leakage current, special attention should be paid to measure the insulation resistance between the cable core and appearance, must take good screen end button "G", when the air humidity is big or the cable insulation surface and not clean, the surface leakage current will be large, in order to prevent the object to be measured by leakage of the internal insulation effect caused by measurements, a metal shielding ring and cable in appearance, connected with the megohmmeter "G" end.
Correct measurement methodModern life is changing with each passing day, and people can not live without electricity. In the course of power consumption, there is safety in electricity, in electrical equipment, such as motors, cables, household appliances, etc.. One of their normal operations is the degree of insulation of their insulating material, i.e., the value of the insulation resistance. When heated and damped, the insulation ages. Its insulation resistance is lowered. Thus causes the electrical equipment leakage or the short circuit accident occurrence. In order to avoid accidents, the insulation resistance of all kinds of electrical equipment is often measured. Determine whether the insulation meets the equipment requirements. The measurement of general resistance is usually done in two ways: low voltage measurement and high voltage measurement. The insulation resistance due to the general value of higher (usually a trillion European level). Measurements at low voltage cannot reflect the true insulation resistance at high voltage conditions. The ohmmeter is also called an insulated resistance meter. It is the most common instrument for measuring insulation resistance. It has a high voltage power supply when measuring insulation resistance, which is the difference between it and the resistance measuring instrument. The ohmmeter is used to measure insulation resistance, which is convenient and reliable. However, if it is not used properly, it will cause unnecessary errors in measurement, and we must correctly use the ohmmeter insulation resistance to measure.
When the ohmmeter is working, it generates high voltage itself, and the object of measurement is electrical equipment, so it must be used correctly, otherwise it will cause personal or equipment accidents. Before use, we must first do the following preparations:(1) the power supply of the tested equipment must be cut off before the measurement, and short circuit discharge to the ground shall not be allowed. The equipment shall be electrified to measure, so as to ensure the safety of the personal and equipment. (2) it is possible to eliminate the possibility of measuring the possibility of high voltage electrical equipment. (3) the surface of the tested object should be cleaned, and the contact resistance should be reduced to ensure the correctness of the measurement results. (4) before checking, check whether the European watch is in normal working condition and check its "0" and "the" two points. That is, shake the handle to make the motor reach the rated speed. When the short circuit is in short circuit, it should mean "0" position and open the circuit. (5) the European watch should be placed in a stable and secure place, away from the large current conductor and the external magnetic field.
