Bus bar differential protection Oct logic
Bus bar differential protection Oct logic
(OP)
Can anyone help me regarding BBP open circuit logic or algorithm in details.
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Bus bar differential protection Oct logic
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RE: Bus bar differential protection Oct logic
I'm just going to assume when you say open circuit logic, that you are referring to open CT detection.
In a normal Bus Differential scheme without the use of open CT detection logic, if one were to lift a CT wire or if a CT wire were to come out of a lug.......etc, the Bus differential would operate and clear the bus right. Well Open CT detection logic allows the relay to distinguish an actual differential and trip on a fault with in the zone or to remain in service and alarm on an open CT.
Here is how it works:
When the CT circuit opens up, there is a spike or increase in "operating current" and a corresponding dip or decrease of the same magnitude in "restraint current" The increase in operate current and decrease in restraint current should sum to zero. Every relay is a little different but essentially the relay is saying "Is the operate current above X per unit? Is the restraint current below X per unit? Is the vector Sum of restraint and operate current very small (close to 0 zero)? If so, I declare an Open CT"