Sulfur Hexafluoride (SF6) is an excellent gaseous dielectric for high voltage power applications. It has been used
extensively in high voltage circuit breakers and other switchgears employed by the power industry. Applications
for SF6 include gas insulated transmission lines and’gas insulated power distributions. The combined electrical,
physical, chemical and thermal properties offer many advantages when used in power switchgears. Some of the
outstanding properties of SF6 making it desirable to use in power applications are:
V High dielectric strength
V Unique arc-quenching ability
V Excellent thermal stability
V Good thermal conductivity

SF6 circuit breaker is equipped with separated poles each having its own gas. In all types of the circuit
breakers, gas pressure is 2 bars (absolute 3 bars). Even if the pressure drops to I bar, there will not be any change
in the breaking properties of the circuit breaker due to the superior features of SF6 and Elimsan’s high safety factor
for the poles. During arcing, the circuit breaker maintains a relatively low pressure (max 5-6 bars) inside the chamber
and there will be no danger of explosion and spilling of the gas around. Any leakage from the
chamber will not create a problem since SF6 can undergo considerable decomposition, in which some of toxic
products may stay inside the chamber in the form of white dust. If the poles are dismantled for maintenance, it needs
special attention during removal of the parts of the pole. This type of maintenance should be carried out only by the experts
of the manufacturer. (According to Arcing Products and Safety Instruction for Working on SF6 Circuit Breakers)

The circuit breaker must detect a fault condition; in low-voltage circuit breakers this is usually done within the breaker enclosure. Circuit breakers for large currents or high voltages are usually arranged with pilot devices to sense a fault current and to operate the trip opening mechanism. The trip solenoid that releases the latch is usually energized by a separate battery, although some high-voltage circuit breakers are self-contained with current transformers, protection relays, and an internal control power source.