A switching transients of unloaded transformer in power system / Mohd Azmi Zainuddin

This thesis is to studies the switching transients of unloaded transformer in power system during switching operation and PSPICE software was used to determined the voltage at the unloaded(stub) cable. Switching over voltage frequently occurs in electrical power system such switching overvoltage can damage many expensive electrical items such as transformers, cables, motors and others. The effect of overvoltage comes from a sudden increase in magnitude of the travelling wave propagation in a conductor such as transmission line. Damages to power transformers are unwelcome since continuity in power delivery may be seriously disrupted. Furthermore, repairs or replacement, are expensive and time consuming. An example of damage to a transformers is the switching on of unloaded transformers. When the frequencies of the line and transformer matched, very high voltage may appear at the secondary terminals of the transformer. This can damage the insulation of the transformer winding, and finally lead to a flashover from winding to core.