PD Time-sequential Properties of SF6 and SF6 Gas Mixture Including CO2 under ac and dc Voltage Applications

Cold-weather Application of Gas Mixture (sf6/n2, Sf6/cf4) Circuit Breakers: a Utility User’s Perspective

Very low temperatures stress a circuit breaker in a complex manner. Mixed-gas circuit breakers were developed for use at temperatures as low as -50C. These breakers utilize a gas mixture of SF6 and CF4 or SF6 and N2 to prevent condensation of the SF6 gas and have been type tested at -50C to ensure travel characteristics, operating times, and gas tightness are acceptably affected. Today’s mixed-...

Influence of the Gas Volume Size on Spacer Charging in Sf6 under Dc Stress

As Gas Insulated DC transmission systems unite the advantages of space saving installation and large transmission capacity this technology is increasingly discussed and investigated today. The main problem in operation with respect to insulation seems to be identified today, which is charge accumulation on the surface of the spacer. These trapped charges can cause a reduction of dielectric stre...

Study on the Characteristic Decomposition Components of DC SF6-Insulated Equipment under Positive DC Partial Discharge

Pulses with different amplitudes occur when an inner partial discharge fault exists in SF6-gas-insulated DC high-voltage electrical equipment. SF6 decomposes following complex physical and chemical processes. Discussing and quantifying the mathematical relationship of pulse discharge quantities to SF6 decomposition component characteristics is helpful to evaluate and predict the insulation faul...

SF6 High Voltage Circuit Breaker Contact Systems Under Lightning Impulse and Very Fast Transient Voltage Stress

In the past few years gas insulated high voltage circuit breakers have improved considerably, in particular with respect to required drive energy for operation, compactness and reliability. A further reduction in size implies increasing operational field stress inside the breaker and, thus, a reduction in built-in safety margins. If the design comes closer to its physical limits, in particular ...

The marginal impacts of CO2, CH4 and SF6 emissions