Design of a Portable Digital Megohmmeter and Leakage Current Meter
Keywords
Abstract
Reliability and uninterrupted operation of electrical equipment is ensured by many parameters, one of the most important is the quality of insulation. By the concept of insulation resistance it is necessary to understand the ability of the material of which the insulation is made to resist the electric current flowing in electrical equipment. The condition of the insulation affects the quality of the power supply as a whole. The throughput and durability of the work depends on the insulation material and its quality, as well as on the state in which it is located. Most conductors are in the form of wires of different thicknesses, covered with a layer of insulation. If the resistance of an ideal conductor should be infinitesimal, then the resistance of an ideal insulation should be infinitely large. However, the reality is that the resistance of the insulating layer is not so large that it could not be measured. Under certain conditions, the so-called "leakage current" flows through it. Its value may be unacceptably large. Gradually, however, the properties of the insulation coating can deteriorate quite quickly. Moreover, any additional external impact, for example, mechanical, can violate the integrity of the weakened insulation. Further, there is a high probability of a short circuit at the site of damage, as well as its ignition due to the high temperature in the short circuit zone. Therefore, it is necessary to periodically check the state of insulation for the magnitude of the leakage currents in it to prevent the destructive consequences of its degradation. Checking the degree of protective properties of insulation is carried out using a special measuring device — a megohmmeter, which measures the insulation resistance in electrical equipment. Measurement of insulation resistance and leakage current allows for safe use and operation of electrical equipment, ensuring efficient operation of the entire power supply system. An analysis was made of existing solutions. A portable digital device was developed that included a megohmmeter and a leakage current meter, and provides a rated test voltage of 250, 500, or 1000 V to measure leakage current or insulation resistance.
