Double Breaker vs Breaker and a Half

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mbrooke

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Is breaker and a half more reliable then double breaker double buss? I am starting to get the idea the old notion is a myth :blink:
 

topgone

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Haven't been into a double-bus configuration but most of my experience in my other life has been up the breaker and a half. 1 and 1/2 configuration is for me, a very flexible arrangement. That arrangement allows for a shorter bus length compared to a double-buss. You are given the options on which element to shutdown for maintenance without impairing the others.

Basically, you already two busses in a 1 and 1/2 breaker arrangement but you are using three breakers in between the busses. AFAIK, the double buss configuration has the same numbe of busses but use only two breakers in between the busses. Loads and generators take off alternately on each breaker bay.
 

GoldDigger

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It alludes to double breaker double buss being the most reliable, but I am willing to question that. IMO, breaker and a half might be superior.
Depends on whether you are defining reliability in terms of odds of any component failing, odds of a failure disabling any load or group of loads, or resilience in terms of ease of doing maintenance with minimal impact on the loads.
 

mbrooke

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Depends on whether you are defining reliability in terms of odds of any component failing, odds of a failure disabling any load or group of loads, or resilience in terms of ease of doing maintenance with minimal impact on the loads.



Id say breaker and a half beats all of the above. For example, it is impossible (at least far less likely) to loose both buss bars in a breaker and a half scheme.
 

topgone

Senior Member
Id say breaker and a half beats all of the above. For example, it is impossible (at least far less likely) to loose both buss bars in a breaker and a half scheme.

You are correct. You have the option as to which element you need to shutdown/take out for maintenance, hence your failure rates will be reduced.

Experience-wise, we were also able to re-configure our breaker and 1/2 busses to have a one-on-one, generator to load arrangement. Both busses were isolated from the load-generator connections-->both busses disconnected at side breakers and keeping the center breaker energized. We were told to make sure we will have a generator left feeding the station load, to survive a very strong storm!
 

mbrooke

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You are correct. You have the option as to which element you need to shutdown/take out for maintenance, hence your failure rates will be reduced.

Experience-wise, we were also able to re-configure our breaker and 1/2 busses to have a one-on-one, generator to load arrangement. Both busses were isolated from the load-generator connections-->both busses disconnected at side breakers and keeping the center breaker energized. We were told to make sure we will have a generator left feeding the station load, to survive a very strong storm!

Exactly what I was thinking. And in the real world if a buss is taken from service and the other is lost for what ever reason, the center breakers can still link 2 circuits together. Intelligent planing can have circuits pared in such a way that generation (source) circuits feed load circuits. Heck a 345/138kv autotransfomer can still feed a critical transmission line even with both busses cleared.

In your case, why were both bus bars taken from service?
 

topgone

Senior Member
Exactly what I was thinking. And in the real world if a buss is taken from service and the other is lost for what ever reason, the center breakers can still link 2 circuits together. Intelligent planing can have circuits pared in such a way that generation (source) circuits feed load circuits. Heck a 345/138kv autotransfomer can still feed a critical transmission line even with both busses cleared.

In your case, why were both bus bars taken from service?

The rest of the feeders/generators were actually "on" through the other paths of the two busses. We were expecting the possibility of feeder lines to be brought down to the ground as storm winds were quite strong, hence a blackout in the offing. Only those generator-load pair were secured so we don't have to be doing a cold start after the storm, it worked fine.:)
 

mbrooke

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The rest of the feeders/generators were actually "on" through the other paths of the two busses. We were expecting the possibility of feeder lines to be brought down to the ground as storm winds were quite strong, hence a blackout in the offing. Only those generator-load pair were secured so we don't have to be doing a cold start after the storm, it worked fine.:)

But wouldnt the same happen with both busses energized? Or was the fear of debris being blown into the buses?


The breaker and half scheme is a bit complicated protection system.

How does it compare to others? If I am correct India uses breaker and half at the 400kv level bus single breaker double buss at 220 kv?
 
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