Design philosophy of the GIS tie breaker is normally open

[lemo]

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Power plant two GT and HV 230kV GIS two Line breaker and one tie breaker combination substation*
this tie breaker design philosophy is normally open* but client request tie breaker is normally close.

Q1. which standard mention this tie breaker normally position.

Q2. what advantages or technical/operational benefits this tie breaker normally open.

Q3. what advantages or technical/operational benefits this tie breaker normally close.



Please advice.

kaisor.kim@gmail.com

[surgeArrester]

the answers to these depends on perspective and ones specific need to reliability..


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[BabyBear]

Is the GIS a double-bus single-breaker scheme? If yes* the following reasons why it is normally open:
1. Although the GIS constitutes one substation* the normally open tie breaker separates the source or sink of power through two paths. If one part of the double bus is to be maintained* the circuit affected by the maintenance will be transferred by closing the tie breaker so the power/load path will flow in the remaining bus.

2. Its a reliability philosophy as what SurgeArrester mentioned. No exact standard could be cite to illustrate the reasons why normally open tie breaker.

3. Disadvantages? Too many switching schemes when there is maintenance on one part of the bus illustrated in Item 1. When standard switching sequence is not properly enforced due to rigorous switching actions* the danger of VFT and arcs are imminent* although the "gas" in GIS takes care of that scenario as much as possible.