A new 145-kV high-voltage circuit breaker from ABB, the 145PM63-B, utilizes a new high-performance interrupter to serve 121-145-kV applications at 40-, 50-, and 63-kA ratings without need for shunt capacitors to meet ANSI standards for short line fault interrupting.
The 145PM63-B design provides opportunities for installation in applications previously not served by 145PM offerings. The breaker footprint and overall dimensions are identical to earlier 145PM designs. The breaker retains the advantages of spring-hydraulic drive technology with the HMB-2 operating mechanism, a more powerful version of the well-proven type HMB-1 unit used by its predecessor. Key features of the new breaker include:
- Lower engineering, acquisition, installation and maintenance costs by eliminating the need for shunt capacitors for applications where short-line fault interrupting capability is required;
- Simplified SF6 gas system, eliminating potential leak points;
- Elimination of breaker-mounted capacitors, lowering total weight and reducing foundation costs;
- Easy replacement of current transformers in the field without removing the bushings, significantly reducing maintenance or modification expense;
- Modularized high-performance interrupter platform, enabling the one-piece units to be easily removed and replaced in the field during maintenance. This cuts maintenance cycle time on an interrupter to approximately one day or less. A factory exchange program can further reduce replacement expenses through use of pre-tested units which require no field adjustments; and,
- Composite bushings with silicone rubber insulators that offer a pollution resistant, lighter-weight construction (porcelain bushings optionally available).
Raj Nayar, a business development manager at Siemens Power Transmission & Distribution, took some time to explain to us, and our readers, the difference between live-tank and dead-tank circuit breakers. The information he provided may help to clarify the advantages, disadvantages and different applications of these crucial components of the high-voltage power infrastructure.
Circuit Breakers: Live Tank vs. Dead Tank
Q: What is the basic difference between a dead-tank and a live-tank circuit breaker?
A: The tank that houses the interrupting chamber is grounded zero potential in a dead-tank breaker, while a live-tank circuit breaker is at live potential.
Q: Are there specific applications where a utility would choose one type of breaker over the other?
A: Dead tanks are predominantly used in ANSI /North American influenced markets. Similarly, live tanks are used more in IEC / European influenced markets.
Q: What is one specific advantage/disadvantage of one over the other?
A: At extra-high-voltage levels the amount of SF6 required in live tanks is far less than in dead tanks.
Q: Does Siemens PTD make both live-tank and dead-tank circuit breakers?
A: Yes, dead tank up to 550 kV and live tank up to 800 kV currently. 1,000-kV breakers are at the development stage.
Q: What does Siemens PTD sell more of: dead tank or live tank?
A: North America is predominantly dead tank. The rest of the world is live tank, and that exceeds the dead tank market.
Q: What’s the highest voltage rated circuit breaker you’re currently making? Is it dead-tank or live-tank? Have you sold any?
A: 800-kV live tank. Many units have been sold throughout the world.