The polarisation index test of electrical insulation is the key criteria for testing the healthiness of electrical system.
The failure of the insulation cause the device to fail. The insulation resistance value goes down as the temperature increases. The insulation resistance gets halved with every increase in temperaure by 10 degree centigrade.The moisture also cause the insulation failures. The checking of insulation resistance is one of the method for ensuring healthiness. However,…
The CTs must be grounded at the single point. The grounding of the CTs at the multiple points lead to the voltage of different magnitude at two points. The realy used for the differential protection may operate when the fault is outside of the protection zone.
The knee point voltage(KPV) of the current transformer tells the information about the magnetization characteristics of the current transformer. According to IEC,the knee point voltage is defined as a point where 10% increase in the secondary voltage cause an increase in the secondary current by 50%. The current transformer gets saturated at this point.…Continue