Brief introduction of main components used in surge arrester
Let’s give you a brief introduction of main components used in surge arrester.
Arc chopping/spark gap
Principle: is shaped like a horn two electrodes separated by an insulating material, each other a short distance. When the potential difference between the two electrodes reaches a certain level, the charge will pass through the two angle-sparking discharge space, whereby the over-current release into the ground.
Advantages: large discharge capacity (more than can be achieved 100kA), low leakage current;
Disadvantages: residual pressure (2-4kV), slow reaction time (≤ 100ns), have to follow the current (continuous flow).
Metal Oxide Varistor
Principle: The element at a certain temperature, the conductivity increases with the voltage increases sharply. It is a main component of zinc oxide varistor metal oxide semiconductor. No pulse was high resistance state, once the response pulse voltage, the voltage limit immediately to a certain value, the impedance is low mutation.
Advantages: low residual voltage, fast response time (≤ 25ns), no follow current (freewheeling);
Disadvantages: leakage current is large, relatively fast aging.
Gas Discharge Tube
Principle: it is a ceramic or glass packages, filled with low pressure inert gas protection device, generally two electrodes and the three-electrode two structures. The basic working principle is a gas discharge. When the electric field strength between the poles exceeds the breakdown strength of the gas, it caused the discharge gap, thereby limiting the voltage between the poles, so that the gas discharge tube in parallel with other devices to be protected.
Advantages: pass flow capacity, high insulation resistance, leakage current;
Disadvantages: higher residual pressure, slow reaction time (≤ 100ns), operating voltage accuracy is low, there is follow current (continuous flow).
Transient Voltage Suppressor
Principle: is a special component for suppressing over-voltage. The core part has a larger cross-sectional area of the PN junction, the PN junction operating in the avalanche mode, a strong pulse absorption capacity.
Advantages: low residual voltage, the action of high precision, fast response time (<1ns), no follow current (continuous flow);
Disadvantages: poor resistance to flow, flow capacity is small, usually only a few hundred amperes.