What Is Auto Reclosing?

17th Feb 2022

If you’re wondering what Auto Reclosing is, it’s a type of circuit breaker with an automatic closing mechanism. These systems are often installed on towers or poles. The name comes from the ANSI device number 79. 

In general, they are used to prevent the power system from tripping out when a circuit breaker is turned off. Depending on the size of your home or office, you may have multiple auto-reclosing systems.

When an auto-reclosing circuit breaker detects a fault, it closes the line and waits a predetermined period of time before reclosing the circuit breaker. If the fault still persists, the controller recloses the breaker and checks for the fault again. Then, if the fault persists, it trips again. At that point, it recloses the circuit breaker for a second time and continues to do so until the fault has been resolved.

If you want to know more about auto reclosing, continue reading this article. 

What is Auto Recloser and How Does It Work?

Auto reclosers protect consumers from high costs of electrical bills due to the risk of a power outage. This electrical device is used to restore power to a transmission line after a fault. When a fault strikes the electrical grid, the recloser will automatically shut off the power and reconnect the circuit. If this happens, the recloser will isolate the fault. Once the power is back on, it will open the circuit again and reconnect it. This process is called auto reclosing.

The automatic reclosing process involves sending a trip command to a circuit breaker (CB) to isolate a fault. The other healthy phases stay closed. The auto recloser relay closes the CB pole of the faulty phase after a period of time, usually one second. This allows the fault to clear and the line to hold. The auto recloser is a highly advanced system that saves lives and prevents electrical grid failures.

The auto recloser lockout setting controls the number of attempts the recloser will make before the lockout is reached. Various vendors implement this setting differently, but in general, this setting allows the autorecloser to be reset before it causes a lockout. The reset timer varies between different vendors, so you should compare the vendor’s implementations to determine which one is best suited for your needs.

Generally, an auto recloser will close a circuit breaker at a pre-configured reset time, then reopen it at the next preset reset interval. The breaker will be reset again, and the cycle will repeat until the desired number of reclosing attempts is reached. Eventually, an auto recloser will reach a lockout state after all the reclose attempts have failed. Once this happens, the circuit breaker will remain open until a close manual operation is made.

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