- Auto Reclosing Definition: An auto reclosing scheme is defined as a system that automatically attempts to close circuit breakers after a fault, restoring power without human intervention.
- Fault Types: Transmission system faults can be transient, semi-permanent, or permanent, with most faults being transient.
- Auto Recloser Working Principle: The auto reclosing system makes multiple attempts to close the circuit breaker if a fault is detected, with prescribed delays for semi-permanent faults.
- The auto reclosing system makes multiple attempts to close the circuit breaker if a fault is detected, with prescribed delays for semi-permanent faults.: Auto reclosing schemes are crucial in high voltage transmission systems to prevent power loss and maintain system stability.
- Fault Clearance Statistics: In overhead transmission systems, 80% of faults are transient, which can be cleared by auto reclosing schemes.
The extra high voltage transmission lines transmit huge amount of electric power. Hence, it is always desirable that the continuation of power flow through the lines should not be interrupted for a long time. There may be a temporary or permanent fault in the lines. Temporary faults get automatically cleared, and these do not require any attempt for fault rectification. It is normal practice by the operators that after each initial faulty tripping of the line, they close the line. If the fault is transient, the line holds after the second attempt of closing the circuit breaker, but if the fault persists, the protection system again trips the line and then it is declared as permanent fault.
Since these lines carry so much power, any delay in manual reclosing can cause significant loss in cost and stability. Auto reclosing schemes prevent these delays by automatically restoring power. We categorize electrical transmission faults into three types: transient, semi-permanent, and permanent.
- Transient Fault
- Semi Permanent Fault
- Permanent Fault
Transient faults clear up momentarily on their own. Semi-permanent faults are similar but take a bit longer to clear, often caused by debris falling on live conductors. These faults clear once the cause burns away. For both fault types, the line trips but can be restored by closing the circuit breakers.
An auto-reclosing scheme handles this process. In overhead transmission systems, 80% of faults are transient, and 12% are semi-permanent. The auto-reclosing system attempts to close the circuit breaker multiple times until the fault clears. If the fault persists, the system permanently opens the circuit breaker. A set time delay can help clear semi-permanent faults before reclosing.
