The protector forms the protection circuit together with the
second-grade protection of the switch, which can provide
the following protection against over-voltage and over-current.

Features:
1) The surge voltage caused by lightning on or around the external line.
2) The short-time AC voltage inducted on external lines, when the power
line, the power system or the electric railway system is broken
down in the neighborhood of the external line.
3) The external line directly collides against a 220V power line.
4) Each protector has test eyelet, which can coordinate with the special
test plug to test the external line as well as the components inside
the protector.

Technical Specification:
1) Contact resistance difference between a line and b line: ≤2Ω
2) Lower Voltage Limit: GDT protector (100V/s escalating rate) ≥190V
3) SA protector (100KV/s escalating rate) ≥190V
4) Upper Voltage Limit: GDT protector (100V/s escalating rate) ≤260V
(1KV/us escalating rate) ≤800V
5) SA protectors (100KV/s escalating rate) ≤260V
(1KV/us escalating rate) ≤400V
6) Insulation Resistance ≥1000Mohm(100V DC)