The built-in distribution substation ISET is designed for distribution of electric energy in 6-20 kV networks with insulated neutral.

The main elements of a built-in distribution substation ISET are the following:

• HV switchgear

Ultima cubicles 6...10 kV with solid insulation are used for HV switchgears. Cubicles of this type incorporates reliability, simplicity and safety, confirmed by tests in the scientific and technical center of the Federal Grid Company.

The range of Ultima cubicles allows to solve any application and is available as follows:

- Circuit breaker cubicle;

- Load break switch cubicle;

- Load break switch-fuse cubicle;

- Busbar connection cubicle;

- Earthing switch and voltage transformer cubicle;

- Earthing of main busbars cubicle;

- Auxiliary transformer cubicle;

- Metering cubicle.

• Operational current system

- The system of AC operational current (ID-AC Operating Current Board) is equipped with uninterruptible power supplies, and in autonomous mode it provides power from rechargeable batteries which perform a function of energy storage;

- The system of DC operational current (ID-DC Operating Current Board) is equipped with LGBT-transistor or thyristor-type charge and rectifier modules. In autonomous mode, similarly to the AC system, it provides power from rechargeable batteries, which perform a function of energy storage.

• Power connections

Sections of the built-in distribution switchgear are connected by cable. Each cable power bridge is terminated by a cable coupling.