What Are The Different Types of Transfer Switches?

A transfer switch or an ATS is a switching gadget that is designed to transfer power from one source to another. Usually, it is used to transfer power from the Mains power supply to a generator.

This means that the transfer switch is connected to the primary power source, the Mains and the back-up power source, the generator. It acts as an intermediary between these two sources of power. Sometimes, the transfer switch acts as a rack-mounted power supply for a device that’s connected to a power source with one cord.

A transfer switch is beneficial in several regards. It is not only one of the various ways that make a generator safe for electrical appliances, but also it’s the easiest way. You can use an extension cord instead of a transfer switch but it’s utterly dangerous. There are serious chances of a back feed.

Also, there are a few devices that cannot be connected to a generator using extension cords. For such devices, you need to buy a transfer switch to ensure a safe supply of power during an outage. By using a transfer switch, one can connect multiple household appliances to a generator and keep them safe.

Types of Transfer Switches

If you are researching on transfer switches, you must know the different kinds of transfer switches available in the market.

We have discussed each of them in detail below. Let’s go through them one by one.

Open Transition Switches

These types of transfer switches cut off one connection completely before supplying power to another circuit. This eliminates any chances of back feeding. You must know that back feeding into your power system is extremely dangerous. The “open”  transition switches prevent back feeding by disconnecting the power supply for a split second when the back feed occurs.

Though the open transition switches ensure your safety, this disconnection tends to wear out your appliances faster. Not just the appliances but also the power system. Therefore, it’s wiser to go for a smoother transition, especially if you reside in a place that experiences frequent power outages.

An emergency system typically uses an open transition. This means, there’s a disconnection of power momentarily when it’s switched from one source of power to another.

Both the manual transfer switch and the automatic transfer switch are an example of open transition switching.

Manual Transfer Switches

Manual transfer switch is the simplest model of transfer switches. One can guess the type of operation from the name itself. Manual intervention is needed for the switch to perform.

This means when there’s a power outage, a person has to manually operate the switch to start its operation. Only after manually switching on the transfer switch, the power will be transferred from one source of power to another.

Now when the power supply is restored back to normal, the individual will have to switch off the transfer switch manually to switch power supply back to the Mains and enable the generator to cool down.

Automatic Transfer Switches

This type of transfer switch is just the opposite of the Manual transfer switches. Therefore, the operation of these switches is automatic.

The process in which these switches work is the same. The only difference is that the starting and stopping of the generator and operation of these switches is automatic. There is no need for manual intervention. Automatic transfer switches normally use open transition switching.

Closed Transition Switching / ‘bumpless’ Switching

The next category of transfer switches is closed transition switching. These are also called bump less switching because of the smooth transition they offer. Due to their advanced operation, they come with better integration and more design as compared to the open transition switches.

They function similar to the Automatic transfer switches, with the added benefit of bump less switching.

When there’s a power failure, the generator will start automatically to provide power to the appliances. Now, when the normal power supply is restored, this device restores the site power from the generator to the Mains power source, without any disconnection. That’s why this is an example of a bump less transition. Evidently, the switching action is extremely fast and is done in seconds.

Soft loading transfer switches

These types of transfer switches allow your generator and utility to synchronize. These switches also reduce the possible differences in voltage or frequency transients when there’s a switchover in the source of the power.

Static transfer switches

A static transfer switch has no moving parts. It contains powdered semi-conductors, which allow the switch to shift between multiple circuits and switch over power sources. It’s an example of a non-mechanical system that enables faster switching.

To transfer a load between two power sources, semiconductors like Silicon-controlled rectifiers( SCRs) are used. The transfer of power happens extremely fast. These types of switches are ideal to be used in places where independent and stable sources of power are used.

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The Bottom Line

By now you know the various kinds of transfer switches to choose from. If you are confused about which one would be best suited in your case, consult a professional. Also, we would advise homeowners to professionals do the installation.