Fault level on tie bus
Fault level on tie bus
(OP)
Gooday,
We have a 30kV switchgear lineup with tied section A and B. The tie breaker is normally open. However, it will be closed for a paralled incoming operation not more than 20 seconds before switching for maintenance . The worst case of fault level on 30kV bus is parallel incoming operation with closed tie breaker. What is the fault level when we design? The parallel operation with closed tie breaker or separate operatin of section A and B with open tie breaker?
Thanks,
Parkpower
We have a 30kV switchgear lineup with tied section A and B. The tie breaker is normally open. However, it will be closed for a paralled incoming operation not more than 20 seconds before switching for maintenance . The worst case of fault level on 30kV bus is parallel incoming operation with closed tie breaker. What is the fault level when we design? The parallel operation with closed tie breaker or separate operatin of section A and B with open tie breaker?
Thanks,
Parkpower






RE: Fault level on tie bus
JIM
RE: Fault level on tie bus
"Throughout space there is energy. Is this energy static or kinetic! If static our hopes are in vain; if kinetic — and this we know it is, for certain — then it is a mere question of time when men will succeed in attaching their machinery to the very wheelwork of nature". – Nikola Tesla
RE: Fault level on tie bus
In the real world, there are sometimes exceptions, but if you are designing new equipment, I'd assume the worst-case, especially if you are stuck on the 20 seconds. These transfers are often done with 1 or 2 seconds instead of 20.
You have to also consider that the arc-flash level will nearly double when the two sources are in parallel, even if the breakers are adequately rated.
RE: Fault level on tie bus
RE: Fault level on tie bus
worst case shall be my choise. Switchgear short current is rated for 1s or 3s. 20 second is really a long time.
Parkpower
RE: Fault level on tie bus