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What You Need To Know About Disconnect Switches

What You Need To Know About Disconnect Switches
The Siliconreview
21 June, 2021

Disconnect switches, also popularly called isolator switches, load break switches, or safety switches, are utilized to isolate an electrical circuit by interrupting the movement of electrical current. Therefore, by quickly halting the flow of electrical current, these disconnect switches can allow emergency shutdowns or switching to alternate power sources and maintenance. Disconnect switches usually have an enclosure, a wired electrical contact, and an actuator with handles, shafts, and keys. 

This enclosure protects the contacts from some environmental dangers, and it also protects you from touching live circuits. When it comes to the knob or handle, it allows you to either engage or disengage the contacts without any need of opening the enclosure. For most applications, you need to lock the disconnect switch and have it tagged when activated so that you don’t turn on the disconnect switch accidentally. This page explains what you need to know about disconnect switches.

A Switch Disconnector

As explained earlier, a switch disconnector, also known as a power isolator, is designed to disconnect your electrical equipment for repair and maintenance. It is utilized for electrical disconnect for just safety purposes. The aim is to halt the flow of electricity. Remember that without this flow of electricity, the experts can access the devices and equipment and finish the maintenance work safely.  

It means the disconnect switches can halt the flow of electricity from input to output. You can find various types of disconnectors on the market, and some of them may be operated manually. Even better, you can also find automatic switch disconnectors whose usage depends on the disconnector.

With the switch disconnector, you need to understand that it can work as the disconnector. It means the switches or electrical isolators can combine the properties of the load switch as well as the disconnector.

As a result, because a switch disconnector tends to isolate electrical devices, you can expect them to give you several benefits. Further, a switch disconnector can break and even make energized circuits. In this case, you can find many types of switch disconnectors, such as a center brake switch, fuse switch disconnector, circuit breaker, and normal disconnector. It’s also worth noting that all these disconnect switches have similar purposes and objectives.

When you compare a disconnect switch and circuit breaker, you should note that these devices provide different services. The disconnect switch can work with a simple purpose, meaning that it can disconnect the current or power to help you do repair, maintenance, and inspection safely.

On the other hand, a circuit breaker can do several tasks more than a disconnect switch. It can create, carry, and even break the current when it’s under normal conditions. A circuit breaker is designed to meet the needs of a load switch or disconnect switch. So it can provide complete isolation, just like the switch disconnector when required.

You can use a circuit breaker as a protective device to control the flow of electrical current in the same way as a fuse. You cannot expect to see this benefit from a disconnect switch. Simply put, the circuit breaker can halt the circuit in bad conditions, such as short circuit and overloading.

Also, you may control circuit breakers manually, and some also have an automatic operation. There is also a relay in the breaker that can detect the errors and even send signals so that the contacts can close. 

How Disconnect Switches Work

The purpose of a disconnect switch is to provide an electrical disconnect. Many of these come with a manual drive or motor-operated mechanism. Therefore, you need to choose the right operating method for a particular substation. 

The disconnect switch mechanism features several auxiliary switches. These switches can provide a remote sign about the disconnector position, electrical interlocking, and current transfer switching. 

There can always be earthing switches, and these are usually associated with the disconnect switches. These interlocked switches can be mounted using the same frame. But a separate mechanism can also be utilized to prevent the need for various post insulators for earth switches. 

Besides, it can also simply lock, and it’s good to remember that earth switches are designed for dead and isolated circuits. The earth switches don’t have a fault-making ability, so you need to consider some other specific designs to find this fault-making ability.

As explained before, a disconnect switch can be utilized to de-energize the current for service and maintenance. In some cases, a disconnect switch can be used to break the circuit that you find in the electrical distribution. You can motor-operate or do it manually to control a disconnect switch. You can also pair it with the earthing switch to give the needed safety if you are working on any electrical problem. 

Keep in mind that high-voltage disconnect switches are usually utilized in many electrical substations. They use them to isolate transmission lines, transformers, and circuit breakers while doing maintenance. 

It’s also good to know that disconnect switches don’t control the circuit because they have no mechanism to reduce the electric arcs that occur when the high currents are disturbed electrically. Hence, disconnect switches can also be called off-load devices as they cannot break and create currents.

That said, you also need to know that you can find two major disconnect designs called fusible and non-fusible. As the name suggests, fusible disconnect switches use fuses to protect against short-circuiting and over-current. 

On the other hand, non-fusible disconnect switches cannot protect against short-circuiting, so you need to switch on or off the electrical flow. Non-fusible disconnect switches are usually recommended for systems with fault currents of less than 5kA or even those with a dedicated fuse upstream for the dedicated switch.

In conclusion, disconnect switches are usually utilized in industrial applications and power distribution. You can use disconnect switches in power distribution during emergencies so that you can shut down the power to a specific area or even switch from a single power source to another. In industrial applications, you can use disconnect switches to interrupt the power supply to motors and machinery once there is a safety hazard or when you need to do some repairs.