What you need to know about reclosers

What you need to know about reclosers

A recloser refers to a high-voltage and automatic electric switch. This is similar to a circuit breaker that you can find on a household electric line. It’s designed to cut off electric power when there is a problem, such as a short circuit. A household circuit breaker can remain shut off for a household circuit breaker until you manually reset it. On the other hand, a recloser can automatically test the electric line to assess whether or not the problem has been handled.

Therefore, if the issue was only temporary, the recloser can automatically reset itself and restore the electric power. You can use a recloser throughout the power distribution system, such as in the substation and residential utility poles. They come in various sizes that include small reclosers that you can use on a single-phase power line and a large three-phase recloser that you can use on a high-voltage power line and a substation. This post discusses what you need to know about recloser.

Why you should use a recloser

An automatic circuit recloser is known by several electric companies globally as a key device you can use to accomplish your goal, which is to get maximum continuity of electric service to your customers economically and simply. A recloser can sense and stop fault currents, and it can automatically restore service immediately after an instant outage has happened.

The automatic circuit recloser is a self-contained device that has the right intelligence to detect over-current, interrupt fault current, and re-energize the line. But if there is a permanent fault, the recloser can lock open after a few preset number of operations. This isolates the faulted part from the main section of the system.

A recloser can save the electric companies significant expenses and time. This is because they can allow the current to be restored automatically immediately after a flicker or two. But for outages that need a repair team, a recloser can reduce the outage area and assist the team members to quickly identify the issue and restore power. Customers of electric companies, such as businesses, residential, institutions, and industries can be saved from the inconvenience and expense regular power outages can cause.

Without a high level of power reliability, most crucial processes that need power use, such as pumps, computers, assembly lines, it would have been hard to run them.

As explained earlier, a recloser can detect any problem that happens and automatically shuts off the power. A few minutes later, the recloser can turn the power back on. However, if the problem continues, it can shut off the power again. And, if the problem persists after three attempts, then the recloser is designed to regard the problem as permanent, so it can remain off. The team members from a power company can then repair the issue on the power line and reset the recloser so that it can restore power. Some examples of permanent problems include a power line or other equipment that gets damaged by fallen trees, vehicle crashes, and lightning strikes.

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Types of reclosers 

You can find a single-phase recloser that you can use to protect a single-phase line, such as taps and branches of a three-phase feeder. You can also use it on three-phase circuits with the load that is mainly single-phase. Therefore, when a permanent phase-to-ground happens, you can block a single while servicing the remaining two-thirds of the system.

Because a single-phase recloser is a lightweight compared to a large three-phase recloser, a single-phase recloser is usually mounted directly to the substation steel structure or pole individually. You can do it by using the built-in mounting hanger bracket that can remove the need for an extra mounting frame.

You can also control a single-phase recloser with a hydraulic control that can be integrated in the recloser tank. Alternatively, you can control it with an electronic control that is installed in a separate enclosure, but this can depend on the design of the recloser.

Another type of a recloser is called a three-phase recloser. You can use this recloser on three-phase circuits to enhance system reliability. You can also use them where lockout of three phases is needed for a permanent fault so that you can prevent single phasing of all three-phase loads like large three-phase motors. Remember that the recloser selection tends to depend on the electrical ratings needed, insulation medium, and interrupting as well as the selection of electronic or hydraulic control.

You can also decide to use a triple-phase recloser that you can control electronically and has three modes of operation. There is a three-phase trip as well as three-phase lockout. All these three phases can simultaneously trip when there is a reclose, over-current, and sequence together.

Another way it can operate is when there is a single-phase trip as well as three-phase lockout. You should note that each of these phases can function independently for reclosing and overcurrent tripping. And, if any phase leads to lockout condition as a result of a permanent fault or if there is a lockout that is remotely or locally asserted, then the other two phases can trip open and lock out. The good thing is that the three-phase loads can be prevented with an extended single-phase energization.

Another way they can operate is when there is a single-phase trip as well as a single-phase lockout. It’s worth remembering that each phase trip that leads to lockout can be independent of each other. This usually happens in residential loads or where single-phasing of the three-phase loads tend to be protected by other means. You can mount a triple-phase recloser to a pole by using a pole mount frame or even in the substation by utilizing a substation frame. You can do this by mounting it directly to the steel substation structure.

Thar said, the intelligence that allows a recloser to detect over-current and select timing operation is offered by its control. The two types of these controls are called an integral hydraulic control and a control that is placed in a separate cabinet.