Switcher/Breaker

[PwrBuf]

1. What is the difference between a dead tank circuit breaker and a live tank circuit breaker? What does 'dead' and 'live' stand for?
2. What are the main differences between circuit switchers and circuit breakers? Why would you choose one over the other?
(Feel free to answer one or both, thanks)

 

[wbd]

Please do a search of the forum as these questions have been discussed previously. Doing a search will yield alot of information.

 

[PwrBuf]

Search is down

 

[cuky2000]

‘Dead’ and ‘live’ stand for the voltage with respect to ground. For dead tank breaker the interrupter chamber is enclosed in a metallic vessel that safely can be touched since is at ground potential (dead). On the other hand, ‘live’ mean that there is a voltage difference of the external breaker chamber with respect to ground (live) and should not be touched without appropriate insulation.

There are construction differences between live and dead tank technology. Dead tank breakers is build with two bushing per phase capable to hold 3 BCTs. The entire assembly can be mounted in a single foundation pad. Live tank breaker chamber is build in a hallow insulator (porcelain or polymer) without BCT. The three poles units typically are vertically mounted in a steel structure that required at least two foundations piers.

Circuit switchers may not have reclosing capability and typically rated for 20 or 31 kA up to 230 kV. Circuit breakers are typically designed for 40kA or 63 kA with reclosing and or single pole capability rated to clear fault in 2 to 3 cycles and capable to operate in HV or UHV

Circ. Switcher could be used to protect transformers while circuit breaker could be used for applications up to 765 kV or higher

 

[busbar]

thread248-37438
thread238-25889
thread238-40469

 

[jbartos]

Suggestion: Reference:
1. IEEE Std 100-2000 "Dictionary"
a) Circuit Switcher is a circuit interrupting device with a limited interrupting rating as compared with a circuit breaker. It is often integrated with a disconnecting switch. Its design precludes the integration of current transformers with all associated ramification of it.
b) Circuit Switcher is a mechanical device with an integral interrupter, suitable for making, carrying, and interrupting currents under normal circuit conditions. It is also suitable for interrupting specified short-circuit current that may be less than its close and latch, momentary, and short-time current ratings. This device may be suitable for transformer protection where the majority of faults are limited by transformer and system impedance.

 

[XFB]

Live tank CB's are generally cheaper, however overall project cost usually ends up similar since you have to add on cost of separate CT's, CT structure, foundations, floor space, connections & connectors, labour,...

Dead tank CB's enable you to consider the CB as a complete subsystem from the supplier, ready to connect, with BCT's already mounted and marshalled in the control cubicle.

If your protection scheme has diff prot with cross over of CT zones, then the DT CB will accept more easily CT's on both sides of the CB.

From a user perspective, modern 38kV gas-insulated DT CB's bring the benefit of virtually no maintenance and excellent protection from environment(pollution, ice,...).

Also, I found that DT CB's offer better performance and type testing than standard live tank, such as internal arc fault withstand, seismic withstand, and the gas-insulated environment preserves the BIL level over time.