S-JXB Series Transformer Neutral Point Over voltage Protection Device is specially used in 110kV, 220kV transformer neutral point return circuit, which will prevent the neutral point insulation from overvoltage damage, and realize the conversion of earthing running and earthing-free running of transformer neutral point.
Required by the operation of electric power system, most transformer neutral points of 110~220kV effective earthing system adopts earthing-free operation method. The transformer mainly adopts grading insulation structure, whose insulation level is relatively low. So lighting overvoltage, operation overvoltage and work frequency transient overvoltage protection shall be adopted in earthing-free transformer neutral points.
Presently, the neutral point overvoltage protection mainly adopts protective gap, arrester protection and parallel connection protection of gap and arrester. The protective gap mainly restricts work frequency overvoltage, operation overvoltage and resonance overvoltage. It can also restrict lighting overvoltage to some extent. Zinc oxide arrester protection can mainly restrict lighting overvoltage; when it is required to protect lighting, work frequency and operation overvoltage, the parallel connection protection of gap and arrester can be adopted. At this moment, the gap can protect both the neutral point of transformer and the arrester. It can also prevent the arrester from explosion because of insufficient flow.
a) Ambient temperature: -40℃～+40℃；
b) Altitude: not exceed 2000m;
c) Wind speed: no more than 34m/s;
d) Iced thickness: no more than 10mm;
e) Earthquake: intensity no more than 9 degree;
f) Dirtiness condition: suitable for pollution region IV class and below;
g) No heavy shock frequently, no explosive substance, inflammables or caustic;
h)Sun-ray： 1000W/m2（It is a fine day at noon）