Circuit Switcher (or live tank circuit breaker) gas monitoring

[stevenal]

I've got a question in to the manufacturer, but just in case they fail to explain it to me adequately, perhaps folks here can help.

Manufacturer A can provide an optional gas monitoring relay in the cabinet. It's a radio device that communicates to pressure sensors in the pole units. Since the interrupter housings are at line potential, the radio link makes sense.

Manufacturer B provides a gas monitoring relay standard: "This monitor is located inside the base assembly next to the operator cabinet assembly and is connected to the pole units by copper tubing."

Since the base assembly and cabinet are at ground potential, how has manufacturer B not compromised the insulation level of this device with the conductive tubing?

Thanks

 

[dpc]

I can't answer your question, but anecdotally, my experience with the radio transmitter type sensor not been good. Repeated false alarms to the point where the alarm in SCADA was totally ignored.

 

[cuky2000]

Stevenal,

Beware that some manufacturer could sell you a circuit breaker with a nameplate called as circuit switcher.

This manufacturer will not have problem to supply the gas monitoring relay in the cabinet. Other manufacturer could provide the gas monitoring at added price but some manufacturer that only produce circuit switcher may have difficulties to deviate from the tested and approved prototype design.

 

[davidbeach]

There’s essentially no difference between a vertically mounted live tank breaker and a circuit switcher these days. Early circuit switchers were something else altogether.

 

[stevenal]

Cuky2000,

I think a design that began life as live tank breaker and later tested to meet IEEE switcher specifications is just fine. We already have several on the system.

Manufacturer B clarified today that the interrupter tank and the hollow insulator that supports it share the same gas space. The tube in question only penetrates into the bottom of the lower insulator.

Sounds like the vacuum in dry air designs are now available for 69 kV for a 30 to 50% premium.

 

[cuky2000]

Stevenal,

Yes, 69 kV vacuum breakers are commercially available. We are currently installing a few of dead-tank vacuum breaker rated for 72kV max., 3000 A continuous, 40 kA, 3 cycles. Those breakers are generally equivalent in rating to the SF6 units.