Overview
Surge arrester is a kind of overvoltage protector, which is mainly used to protect various electrical equipment (transformers, switches, capacitors, arresters, transformers, generators, motors, power cables, etc.) in power systems, railway electrification systems, and communication systems. .) The protection of atmospheric overvoltage, operating overvoltage and power frequency transient overvoltage is the basis of power system insulation coordination.
Operating principle of disconnector
When the arrester works normally, the disconnector will not act, showing low impedance, which will not affect the protection characteristics of the arrester. The arrester with the disconnector is safe, maintenance free, convenient and reliable. There are two types of lightning arrester disconnectors: hot explosion type and hot melt type. The hot melt type disconnector cannot be quickly disengaged in case of failure due to its own structural principle defects, so the hot explosion type disconnector is commonly used today. The early thermal explosion disconnector was used by GE as the silicon carbide valve arrester. Its working principle is to connect a capacitor in parallel on the discharge gap, and the thermal explosion tube is placed in the lower electrode of the discharge gap. When the arrester works normally, the voltage drop of lightning and operating impulse current on the capacitor is not enough to make the discharge gap breakdown, and the disconnector does not act. When the arrester is damaged due to fault, the voltage drop of power frequency fault current on the capacitor makes the discharge gap breakdown and discharge, and the arc continues to heat the thermal explosion tube until the disconnector acts. However, for neutral point directly grounded systems above 20A, this type of disconnector cannot ensure that it acts under small power frequency fault current. The new thermal explosive release device uses a varistor (silicon carbide or zinc oxide resistor) connected in parallel on the discharge gap, and a thermal explosion tube is installed in the lower electrode. Under small power frequency fault current, the varistor heats up, detonates the thermal explosion tube, and the release device acts.
Features
1. It is light in weight, small in volume, collision resistant, fall proof and flexible in installation, and is suitable for switchgear, ring network cabinet and other switchgear.
2. It is integrally formed, without air gap, with good sealing performance, moisture-proof and explosion-proof, and special structure.
3. Large creepage distance, good water repellency, strong anti pollution ability, stable performance, and reduced operation and maintenance
4. Unique formula, zinc oxide resistance, low leakage current, slow aging speed and long service life
5. The actual DC reference voltage, square wave current capacity and high current tolerance are higher than national standards and international standards
Power frequency: 48Hz~60Hz
Conditions Of Use
- Ambient temperature: -40°C~+40°C
-Maximum wind speed: no more than 35m/s
-Altitude: up to 2000 meters
- Earthquake intensity: no more than 8 degrees
- Ice thickness: not more than 10 meters.
- The long-term applied voltage does not exceed the maximum continuous working voltage
