Hydropower Plant,Substation/Electrical Machine Repair and Maintenance

GIS (Gas Insulated Switchgear) Typical Arrangement.....

Transformer Differential Protection Scheme..........

Are you filling Oil in to the transformer? Check your Oil insulating properties. The Oil minimun BDV(Break Down Voltage) value should be 30kV/2.5mm otherwise your transformer may cause considerable demage.

Do you know ? the short circuit current generally 10 times of normal rated current.

What is corona?
Ans: The phenomenon of voilet glow,hissing noise and production of ozen gas in an overhead transmission line is known as Corona.
Factors affecting Corona:
1.Atmosphare
2.Conductor Size
3.Spacing between conductor
4.Line voltage
Advantage of Corona:
1. Due to corona formation the air sourring the conductor becomes conducting and hence virtual diameter of conductor is increase. And increase diameter reduces the electrostatic stess between conductors.
2.Corona reduces the effects of transients production by surges.
Disadvantage
1.Corona accompanied by a loss of energy and effects transmission efficiency of line.
2.Ozen is produces by corona which may cause corrosion of conductor due to chemical action.
3.Corona cause inductive interfarance with neighbour communication line.

An ideal transformer is one that has:
1.No winding resistance.
2.No leakage flux(same flux links both winding).
3.No iron losses in the core.