As a standard practice installer or contractor shall arrange for the witnessing of the following tests on the fully equipped switchboards (main, submain distribution boards and Motor Control Centers MCC) including primary bus bars and connections at the factory, in accordance with IEC 439-1: High voltage power frequency tests on main and auxiliary circuits Dielectric/insulation… Read More »
Cable sizing is done based on three parameters: Load current, Short circuit current carrying capacity, Voltage drop. Below are given simple steps for performing cable sizing calculations. Step 1 – Calculate Load Current: Calculate the load current from the load data available. Formula is: I=Load (in kW)/(sqrt(3)V(in kV)p.f) (A) The current obtained has to derated… Read More »
A circuit breaker is a mechanical switching device, capable of making, carrying and breaking currents under normal circuit conditions. It is also capable of making and carrying currents for a specified time and breaking currents under specified abnormal circuit conditions, such as those of a short circuit. Air Blast Circuit Breaker is one of major component… Read More »
A tap changer is a device fitted to power transformers for regulation of the output voltage to required levels. On-load tap-changers (OLTCs) are indispensable in regulating power transformers used in electrical energy networks and industrial applications. OLTC changer alters the turn ratios of the transformer on the system by altering the number of turns in… Read More »
The rated voltage ratio of the transformers at no load normally is specified at 50 Hz, this being related to the principal tapping of the transformer. Tapping shall be provided on the primary winding to provide a ratio variation of +7.5% and –2.5% in steps of 2.5%. The tap charge mechanism is of the off load… Read More »