Learn What is Automatic Circuit Reclosers – ACRs and How It Works

Learn What is Automatic Circuit Reclosers – ACRs and How It Works

The Automatic Circuit Recloser – ACR, is an automated switching equipment installed in electrical distribution networks, usually in 13.8, 27 and 36 kV primary circuits.

They are predominantly located in the primary distribution network, however, to re-establish power supply interruptions more efficiently and quickly, they are also found in Distribution Transformer Stations (DTSs), also known as substations, operating in coordination with an automatic disconnect switch. with a circuit breaker.

The Automatic Circuit Recloser has two basic functions in the distribution system: reliability and overcurrent protection. They are often used to increase the reliability of the electrical power distribution system.

It is a cost-effective solution for disconnecting power grids, and is often used in locations where coordination with other protective and maneuvering equipment is difficult. It is suitable for use in medium voltage overhead distribution networks in coordination with automatic recloser circuit protection. Its operating principle is based on automatic detection of grid failure, interrupting the electrical circuit temporarily.

After a pre-configured period, the ACR will automatically restore power to the mains, checking if the circuit failure still persists. If it persists, it will shut down and after a certain time will restart again.

It can be programmed for two quick reclosing attempts – from 10 to 15 seconds each operation and two delayed attempts – from 20 to 30 seconds, or one quick and three delayed attempts, or according to the need of the electrical circuit where it will be installed. If the fault has been rectified after the first operation, the ACR will remain on and the electrical circuit will be restored, without the need for professional intervention; otherwise, it will shut down and after the set time will attempt to restart again. The maximum number of circuit reclosing attempts is four operations. If reclosing is unsuccessful, a team of professionals should attend the site to rectify the fault and restart the equipment.

They are usually installed in wooded areas,

where the incidence of branches in the distribution network is large, which causes the circuit to be disconnected. Since the time that the branch stays on the net is usually short, probably on the first attempt of reclosing the branch has already left the network and the circuit is reestablished.

Another application of the automatic recloser is to block the reclosing of the electrical circuit. When live (energized) work crews will work beyond ACRS, the lockout function is used because if an accident occurs while working, it will shut down and will not restart again.

After the services are executed, the ACR is removed from the blocking condition. It can also be used to disconnect the electrical circuit for dead line maintenance.

ACR shutdown, reclosing and blocking operations can be performed by specific equipment for maneuvering by trained professionals, or by automation (remote operation).

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