Comparison of varistor and gas discharge
The volt-ampere characteristics of the varistor are continuous and incremental, So it does not exist continued flow, cut off the problem.
Varistor junction capacitance is generally in the order of several hundred to several thousand Pf, In many cases should not be directly applied to the protection of high-frequency signal lines,When applied in the protection of the AC circuit,Because the junction capacitance will increase the leakage current,In the design of protective circuits need to be fully considered.
2, the gas discharge tube includes diodes and Triode discharge tube,Voltage range from 75V-3500V, more than 100 kinds of specifications, In strict accordance with the CITEL standards for production, monitoring and management. Discharge commonly used in multi-level protection circuit of the first stage or the first two stages, From the leakage of lightning transient overcurrent and limiting the role of over-voltage.
Gas discharge tube has the advantage of large current capacity; Parasitic capacitance is small; Residual pressure is low, Generally about 900V;
3, the gas discharge tube can only be placed between N and PE, Because the gas discharge tube conduction delay and conduction after the need for continuous flow, Make the circuit easy to short circuit. So it can not be used between the three phases.
4, varistor is a pressure-limiting components, Discharge tube is a switch-type components! The reaction time is nanosecond discharge tube slower than the varistor! Varistor reaction time is ≤ 25NS,Discharge tube is ≤ 100NS, Varistor has a problem of attenuation! Discharge tube will not!
5, each has its advantages and disadvantages: Varistor is mainly used for power system lightning protection. Gas discharge tube is mainly used for signal lines such as data lines, telephone, cable television, satellite communications and other lightning protection.