GE GL317D Instruction Manual page 26

Opening, continued
Operation
03- 2017
Description and operation
Pole operation
(Interrupting principle)
The table below gives the stages of opening :
Stage
Start of opening When the moving contact (6) separates from the main
contacts (3), the current is switched onto the arc con-
tacts (12). The compression of the (Vp) volume
causes the first rise of pressure.
Thermal effect When the contacts (12) separate, the arc appears and
its energy causes the pressure to rise in the thermal
expansion volume (Vt), closed by the fixed contact rod
(13) and the insulating nozzle (14).
When the rod (13) comes out of the nozzle (14), the
Interrupting and
thermal overpressure in the volume (Vt) is released
assistance
causing an energy blast to occur, just before the cur-
at opening
rent zero passage, ensuring final quenching of the arc.
The (Vp) volume pressure decreases to the ambient
pressure by means of the valve (15) to allow the end
of the opening.
GE Information
Description
3 12
13 14
13 14
6 Vp
12 Vt
Vt Vp 15
Continued on next page.
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