In an ideal world, a cent-percent of the current reaches its intended destination whereas in the real world, some of the current escapes along the way. And thus, the wires are insulated with a resistant sheath to ensure the proper conductivity of the wire. However, it is necessary to know the requirement of these resistance sheaths by understanding the nature of insulation.
Broadly, insulation is of two types- Good insulation and Bad insulation. Good insulation is the optimal amount of resistance which is necessary for the flow of current in a conducting wire in that particular conducting path. However, in various degrees, the enemies of insulation are at work and are combined with the electrical stresses that exist. As pin holes or cracks develop, moisture and foreign matter penetrate the surfaces of the insulation, providing a low resistance path for leakage current.
These leakages may be detrimental to the electrical circuits and machinery, which over the period of time may deteriorate, especially when it is exposed to harsh operating environments such as extreme temperatures, moisture or chemical contamination which might further compromise personnel safety and operating reliability. Therefore, it is critical to always know the electrical condition of the insulation in the equipment all the times.
Thus, Megger insulation testers are a unique type of ohmmeters that are used to evaluate the electrical resistance of insulators. They are engineered to provide preventative maintenance and troubleshooting solutions for various different, high-voltage equipment applications. In low voltage circuit breakers, insulation tests are carried out to make sure the level of resistance between various phases and the phase and ground is of sufficient level.
The main purposes of performing insulation resistance testing include:
1. Used as a quality control measure at the time a piece of electrical equipment is produced;
2. Used as an installation requirement to help ensure specifications are met and to verify proper hookup;
3. Used as a periodic preventive maintenance task;
4. Used as a troubleshooting tool.
Thus, resistance testers are important for maintaining electrical safety, which is critical phenomenon.