Definition: The switch whose contacts open in the air and quenching of an arc achieves by compressed air, such type of switch is called an air break switch.The air acts as a dielectric medium for the air-break switch. It is more effective and reliable as compared to another switch.The air break switch is operated manually when their handle is placed on a ground level.
The air break switches install in outdoor and mainly use for switching and isolation. The air break switch is mostly installed in the distribution network as a switching point. It interrupts the small excitation current of a transmission line or the capacitive charging current. The maximum voltage for the switches is up to 35kV. The air-break switches are classified into two types. They are Single-Pole Air-Break Switch and the Gang Operated Air-Break Switch.
Single pole air-break switch uses for the opening of only one conductor. And for the opening of more than one conductor at a time gang operated air break switch is used. The switches which opened together are called the gang switches. The air-break switches are installed in two ways, i.e., either horizontally or vertically and it is placed on the pole top or in pad mounted metal enclosure.
Working and Construction of an Air-Break Switch
The air-break switch has both the blade and the contact furnished with arcing horns. Arcing horn is the type of metal between which the arc induces due to interrupt current. When the switch is open, the arc spreads farther and farther apart, and the arc lengthens until it finally breaks.
Air break switches are of several designs. Some switches operate from the ground by a holder on the end of an insulated stick; some others are through a system of linkages and opens by a crank at the foot of the pole.
When more than one conductor open, there may be several switches arrange on the same pole. They may be opened singly or all together in a group. Some switches are mounted so that the blade opens downwards and these may be provided with latches to keep the knife blades from jarring open.