The high voltage outdoor SF6 circuit breakers type 7E1/7E2 use the newly developed interrupter chambers.

The interrupter chamber is puffer type with insulating nozzle and two-stage blast cylinder. Arc thermal energy is used for additional compression needed for breaking of short-circuit currents which means that low-energy motor-wound spring or electrohydraulic drive can be used as a circuit-breaker operating mechanism.

The operating mechanism is designed in that way, that with its accumulated mechanical energy, over the main mechanism and auxiliary control mechanism, ensures that all IEC-prescribed switching cycles are achieved. Basically, the mechanism is combined of two part's groups – main and auxiliary kinematical chain. The main kinematical chain transforms electrical energy into mechanical, accumulates it, and if necessary, frees it fast and precisely in time and transforms it into exact movements of the exit lever of the mechanism and holds the mechanism in the stable end positions. Auxiliary kinematical chain ensures logical and automatic sequence of work operations of the main kinematical chain, i.e. controls it. 

Basic parts of the circuit breaker are pole columns and the base with control cubicle. The given main parts are completely finished, tuned and tested in the factory. The pole column is made of interrupter chamber, supporting insulator and crank case assembly, and represents independent gas container. This container is vacuumed in the factory and filled with SF6 gas at overpressure of 0.5 bars.

The base with operating mechanism and control cubicle also represents complete unit, with adjusted parameters, and it is prepared for the installation.

Depending on design, circuit-breaker can be equipped either with single operating mechanism with possibility of three-pole autoreclosure, or with three operating mechanisms (one per pole) with possibility of single and three-pole autoreclosure.

Circuit-breakers are designed, made and tested according to standards IEC 62271-1 and 62271-100