In practice, due to limitations in size, space and cost, rotating machines are not insulated to the same impulse levels as oil Insulated apparatus of same voltage class.
These machines when connected to system are subjected to surge voltage hazards.
The major insulation of any machine is stressed by magnitude of the surge voltage to ground and is protected by a lightning arrester.
The minor insulation of any machine is stressed by rate of rise of Surge Voltage, which can be limited by Surge Protection capacitor.
For the above purpose, normally 0.1 µfd to 0.5 µfd value is used & voltage up to 45 KVAC. YESHA Surge Capacitors are made from highest quality material and every capacitor is subjected to rigid quality control at every stage of production to ensure a quality product. All Surge capacitors are subjected to following tests:
- Tan Delta
- 4.3 times the rated voltage as D.C. Voltage test for 10 Sec.
- Sealing Test for oil leakage
- Surge protection capacitors are normally are a following ratings:
Capacitance: 0.1 µfd to 0.5 µfd;
Voltage: Up to 45 KVAC,
Phase: Single or Three With or without series resistance