A Power transformer should withstand an integer of different abnormal and normal voltage tensions over its anticipated life.
These voltages consist of:
- Operational voltages at the normal frequency.
- Rated frequency over voltages.
- Normal lightning impulses which strike the power transformer or else transmission lines.
- Switching surges which outcome from closing and opening of breakers and switches.
Transient voltages produced owing to resonance amongst the transformer and the system network.
Fast transient voltages produced by vacuum switch actions or by the action of tripping switches in a gas-insulated busbar system
This is a specific arena in which the resultant voltage stresses should be considered in the winding's, and withstand criteria must be well recognized for the diverse voltages and mixtures of voltages. The designer should design the protection (insulation) system to hold out all these stresses.