5/10

AN579 APPLICATION NOTE

Gas tubes: These components are made by two metallic electrodes in a sealed case. Generally the

sealed tub contains a low pressure gas.

Figure 8. Carbon gap based primary protection

Figure 9. Gas tube characteristics

The major disadvantage of this kind of device is its response time, in fact the maximum voltage across the

gas tube depends on the dv/dt of the surge.

Zl

Zl

LINE

EXCHANGE

V

3

1

2

1: Sparkover voltage.

2: Glow discharge voltage.

3: Remaining voltage in switch on mode.