SF6 Gas Technology
Another arc extinguishing technology is SF6 (sulfur hexafluoride) technology. It is popular outside the United States. It is specifically associated with European manufacturers of medium and higher voltage circuit breakers.
SF6 technology was briefly discussed in Module 5, Fundamentals of Circuit Breakers. The main contacts are enclosed in a chamber of SF6 gas, which happens to be a very good dielectric
In short, this arc interruption technology results the in arc energy being used and absorbed, while the arc is simultaneously cooled.
There are several SF6 interrupter designs, but only two types will be covered here:
• Puffer
• Rotary Arc
Puffer-Type SF6 Gas Technology
The puffer-type of SF6 interrupter is the older of the two SF6 technologies. It is more capable but more complicated than the rotary arc-type.
The interrupter is shown below in the closed position, and in the opening sequence.
Typical SF6 Puffer Interrupter in Closed Position
Typical SF6 Puffer Interrupter During Opening Sequence
High Current Arc on Left and Near Current Zero on Right
During current interruption, a piston compresses the SF6 gas in a cylinder, all of which is enclosed in an epoxy-type enclosure. After the main current-carrying contacts part, the current transfers to the arcing contacts. Once the arcing contacts part, the SF6 gas in the compression chamber blasts the arc through the nozzle. The heat created by the arc breaks the SF6 molecules into fluorine and sulfur. Arc energy is absorbed and the arc is cooled.
As current zero is approached, the heat energy subsides as more SF6 gas enters the system. At current zero, the high-pressure SF6 gas flows through the nozzle and extinguishes the arc.
Compressing the SF6 gas requires significant mechanical energy. A circuit breaker equipped with this type of technology requires a higher-energy operating mechanism than is required by an equivalent vacuum circuit breaker. In addition, this interrupter type has a large number of parts.
Rotary Arc-Type SF6 Gas Technology
Rotary arc SF6 technology is less complicated in design than the puffer type. It has fewer parts and does not require such a high-energy operating mechanism. However, it is not effective over as wide a range of short circuit currents and voltages as the SF6 puffer or vacuum. Suitable applications are somewhat limited.
Figure shows a typical SF6 rotary arc interrupter.
As the contacts part, the arc transfers from the main contacts to an annular contact. This causes the current to switch into the coil behind it. The coil's magnetic field, produced by the load current itself, causes the arc to rotate rapidly. The arc is cooled by moving through the SF6 gas.
The SF6 gas is normally at rest inside this interrupter. The arc's movement acts like a mixer, mixing hotter and cooler gas. This helps cool the arc. Contact erosion is also reduced due to this rapid arc movement.
As current zero is approached, the dwindling arc must sustain enough speed to be lost in the SF6 environment in order to withstand the transient recovery voltage. (This is mentioned because the magnetic field produced by the load current causes the all important arc rotation. As the current decreases, the magnetic field decreases, and the arc rotation slows.)
At current zero, the arc is cooled and extinguished.
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SF6 Circuit Breaker
Another arc extinguishing technology is SF6 (sulfur hexafluoride) technology. It is popular outside the United States. It is specifically associated with European manufacturers of medium and higher voltage circuit breakers.
SF6 technology was briefly discussed in Module 5, Fundamentals of Circuit Breakers. The main contacts are enclosed in a chamber of SF6 gas, which happens to be a very good dielectric
In short, this arc interruption technology results the in arc energy being used and absorbed, while the arc is simultaneously cooled.
There are several SF6 interrupter designs, but only two types will be covered here:
• Puffer
• Rotary Arc
Puffer-Type SF6 Gas Technology
The puffer-type of SF6 interrupter is the older of the two SF6 technologies. It is more capable but more complicated than the rotary arc-type.
The interrupter is shown below in the closed position, and in the opening sequence.
Typical SF6 Puffer Interrupter in Closed Position
Typical SF6 Puffer Interrupter During Opening Sequence
High Current Arc on Left and Near Current Zero on Right
During current interruption, a piston compresses the SF6 gas in a cylinder, all of which is enclosed in an epoxy-type enclosure. After the main current-carrying contacts part, the current transfers to the arcing contacts. Once the arcing contacts part, the SF6 gas in the compression chamber blasts the arc through the nozzle. The heat created by the arc breaks the SF6 molecules into fluorine and sulfur. Arc energy is absorbed and the arc is cooled.
As current zero is approached, the heat energy subsides as more SF6 gas enters the system. At current zero, the high-pressure SF6 gas flows through the nozzle and extinguishes the arc.
Compressing the SF6 gas requires significant mechanical energy. A circuit breaker equipped with this type of technology requires a higher-energy operating mechanism than is required by an equivalent vacuum circuit breaker. In addition, this interrupter type has a large number of parts.
Rotary Arc-Type SF6 Gas Technology
Rotary arc SF6 technology is less complicated in design than the puffer type. It has fewer parts and does not require such a high-energy operating mechanism. However, it is not effective over as wide a range of short circuit currents and voltages as the SF6 puffer or vacuum. Suitable applications are somewhat limited.
Figure shows a typical SF6 rotary arc interrupter.
As the contacts part, the arc transfers from the main contacts to an annular contact. This causes the current to switch into the coil behind it. The coil's magnetic field, produced by the load current itself, causes the arc to rotate rapidly. The arc is cooled by moving through the SF6 gas.
The SF6 gas is normally at rest inside this interrupter. The arc's movement acts like a mixer, mixing hotter and cooler gas. This helps cool the arc. Contact erosion is also reduced due to this rapid arc movement.
As current zero is approached, the dwindling arc must sustain enough speed to be lost in the SF6 environment in order to withstand the transient recovery voltage. (This is mentioned because the magnetic field produced by the load current causes the all important arc rotation. As the current decreases, the magnetic field decreases, and the arc rotation slows.)
At current zero, the arc is cooled and extinguished.
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I got such a good information on this topic it’s a very interesting one. You made a good site and I have found a similar website,
please check this one transformer removal visit the site to know more about coopersenviro.
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