Fast Bus transfer in the power plants
Fast Bus transfer in the power plants
(OP)
Hi Guys,
Can any body give the details of fast bus transfer in the power plants(Unit Incomer &station Tie).my questions are
1.What should be the time duration of tie bkr closing when the unit incomer going to trip.
2.Undervoltage trip for the motor fedders in the Unit board
Can any body give the details of fast bus transfer in the power plants(Unit Incomer &station Tie).my questions are
1.What should be the time duration of tie bkr closing when the unit incomer going to trip.
2.Undervoltage trip for the motor fedders in the Unit board






RE: Fast Bus transfer in the power plants
Generally the close and trip commands are initiated at the same time, or very nearly so. Or the trip signal is sent via an early opening or closing breaker aux contact on the closing breaker.
As for undervoltage tripping of motor feeders- this is not much used in the US.
"An 'expert' is someone who has made every possible mistake in a very narrow field of study." -- Edward Teller
RE: Fast Bus transfer in the power plants
RE: Fast Bus transfer in the power plants
With HSTS system for three circuitbreakers(Unit, Station & Bus-tie): when the loss of voltage in one of the two power supply units is detected, the closing command of the bus-tie and the opening command for the switchgear unit without voltage are launched simultaneously.
RE: Fast Bus transfer in the power plants
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If we learn from our mistakes I'm getting a great education!
RE: Fast Bus transfer in the power plants
RE: Fast Bus transfer in the power plants
It explains the pitfalls of undervoltage transfer initiation, closed versus open tranfer, and other issues.
There may be a copy on the Beckwith website. (I can't post my copy.)
RE: Fast Bus transfer in the power plants
We was used also ABB HBT on the REC316*4 base.
Yep, possible option of very fast transfer, that means simultaneously command to open and close, but we cancelled this option, close command only after verification of open position of "faulty" CB.
In the old power plants, we was used a simple logic, NC contact of UAT CB via LOR NO contact is directly connected to the close coil of RAT CB ( ot bus-tie), normal time for full cycle about 120ms.
Best Regards.
Slava
BTW, undervoltage trip for the motor feeders is about 5-7sec with 0.8-0.85Un voltages
RE: Fast Bus transfer in the power plants
Waiting for a confirmed breaker open signal makes sense. Simultaneous open and close commands is a risky solution.
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If we learn from our mistakes I'm getting a great education!
RE: Fast Bus transfer in the power plants
Simultaneous, closing command for bus-tie and the opening command for incomer under detection of loss of voltage, under fault condition need to confirm CB open.
There is facility in HSTS, we can programme logic upon loss of voltage & under fault condition.
Under fault condition transfer time is of the order of 250ms.
RE: Fast Bus transfer in the power plants
Thanks for all response,
My Questions are,
1.actually in my closing ckt of tie bkr in logic they have included the Sync Check Conditions( of UAT I/C synchronism check between Station line PT and Unit Bus PT Should be OK,what may be the reasons for this
2.what should be the time duration of this transfer
RE: Fast Bus transfer in the power plants
Sorry, but you must firstly read manual of one of the type of HBT relay.
Please take in account, your "standard" SC function is "static" function:dU, df, dPhi.
HBT is dynamic function, it's "learn" residual voltage on the bus.
Time duration:...we had also about 500ms
Best Regards.
Slava
RE: Fast Bus transfer in the power plants
Most utility co. requires a backup protection to separate the two sources if the paralleling time exceeds 500ms but that is a long time. I set my back up protection to 300ms.