The Difference Between A Switching Surge Protector And A Voltage-limiting Surge Protector

First of all, the functions of switch-type SPD and voltage-limiting SPD are the same, both of which are used to discharge overvoltage in the line; their working principles are also the same, high impedance when there is no surge, and suddenly change to low impedance when there is a voltage surge, allowing the lightning current to be discharged smoothly. The differences between switch-type surge protectors and voltage-limiting surge protection device are mainly the following three points:

1. Different components used:

1. Switch-type surge protective device:. Usually an integrated manufacturing method is used, and the components used are gas discharge tubes and gaps (ram horn gaps, graphite gaps), which are usually used for T1 level protection.

2. Voltage-limiting surge protector: Usually a varistor is used as a component, also known as a "clamping type" surge protector, which has continuous voltage and current characteristics and is usually used for T2 level protection.

2. Different installation locations:

Power switch type surge protectors are commonly used for T1 level protection, with a waveform of 10/350μs. They are mainly used at the boundary between LPZ0 and LPZ1 (main distribution box, low-voltage transformer incoming line cabinet) to protect system equipment from surge current damage caused by lightning hitting the line.

Voltage-limiting surge protectors are commonly used for T2 level protection, responsible for limiting the residual surge voltage of the upper level surge protector, with a waveform of 8/20μs. They are used at the boundary between LPZ1 and LPZ2 or later lightning protection boundaries (floor distribution box, meter box or terminal box) to prevent transient surge voltage caused by indirect lightning strikes or switch operations.

3. Different matching backup protectors

The voltage protector level of the switch type surge protector is relatively high, and there is power frequency continuous current, so it cannot be used with SSD. The continuous current of the switch type surge protector will frequently cause SSD to malfunction. If the site is not closed in time, the lightning protection path will be blocked. We usually recommend customers to use fuses for backup protection.

The voltage protection level of the voltage-limiting surge protector is relatively low and has leakage current, so it can be used with SSD.