Low level of SF6 pressure b A safety membrane which, in very rare cases of an internal arc, will open in order to let the gas flow to the back of the circuit breaker b Keeping at 0 bar of SF6: v The nominal performance v The capacity to break once at least 80 % of the full breaking capacity v The capacity to withstand at least 80 % of the insulating level b Breaking all types of current without overvoltages.

The breaking medium is sulfur hexafluoride (SF6) used at low pressure. The insulating enclosure containing the circuit breaker pole(s) is equipped with a safety membrane. In addition, the rated characteristics, breaking the rated current under the rated voltage, are generally maintained at zero relative bars of SF6.

Schneider Electric devices have been designed to ensure protection of the environment: b the materials used, both insulating and conductive, are identified and easy to separate and recycle, b the SF6 gas is under control from production through to the circuit-breaker’s end of life. In particular it can be recovered at the end of the circuit-breaker’s life and re-used after treatment in line with the new European directive, b an end of life manual for the product details procedures for dismantling and recycling components.

self expansion LF circuit breakers use the SF6 gas self expansion technique. This technique is the result of many years’ experience in SF6 technology and major research work. It combines the effect of thermal expansion with a rotating arc to create arc blowing and quenching conditions. The result is reduced control energy requirements and arcing contact erosion; this increases mechanical and electrical endurance. The operating sequence of a self-expansion breaking chamber, whose moving part is driven by the mechanical operating mechanism, is as follows: