How does transfer switch work

The main scenario where this becomes a problem is referred to as backfeeding the grid. This surge can cause problems in the line, which may put utility workers at risk.

It can also cause fires in your home or business. There are two different types of transfer switches— automatic and manual.

As the name suggests, an automatic transfer switch seamlessly routes power from the main source to the backup source when needed. Inside and outside a Russell Electric Amp industrial automatic transfer switch.

Manual switches require a human to flip a small lever and turn them on, hence the name. Permanently installed standby generators can vary between needing a manual or automatic, but the automatic is usually the most convenient option.

After all, who wants to really go out in the snow, wind, or rain to turn on a switch to restore power? The price for a transfer switch varies depending on the type of switch and the size of the generator. Most manual switches are less expensive than the automatic ones, for obvious reasons. However, permanently installed standby generators usually come with their own transfer switches included in the cost of the unit.

At that point, the only additional cost you would incur is if you want to upgrade the switch to a better or automatic variety. While you might be tempted to install a transfer switch yourself, it is highly recommended to have a professional electrician do the job for you. The reason is that the switch must be installed on your electrical panel box. In most cases, you will need a permit to install a transfer switch.

While you might be tempted to skip a transfer switch when installing your generator, the truth is that it is almost a mandatory part of owning and using a backup power source. The only real choice you have is to use a manual switch or an automatic one.

This prevents back-feed, which occurs when the power goes back down the utility lines. Backfeed can not only damage the generator but has the potential to cause fires. Worse, back-feed could electrocute workers working on the power lines trying to restore utility power causing injury or even death. Running extension cords to and from appliances can be an awkward and time-consuming hassle especially during an outage. Skip to content Blog. How does a transfer switch work?

Why do I need a transfer switch? Contact Us. Transfer initiation and operation are performed manually, typically by pushing a button or moving a handle; initiation occurs locally.

Manually initiate a transfer by pressing a button or rotating a switch to cause an internal electromechanical device to electrically operate the switching mechanism; initiation can occur locally or remotely. Transfer switch controller is self-acting and completely manages both initiation and operation; initiation is triggered when the automatic controller senses an unavailability or loss of source power followed by operation of the switching mechanism.

This is the most common and typically most economical switching mechanism type. Contactors are constructed as an electrically-controlled, double-throw switch where a single operator opens one set of power contacts while closing a second set.

Routinely used for closing and interrupting a circuit between separable contacts under both normal and abnormal conditions, molded case switches feature simple designs and are capable of supporting either a mechanically operated, over-center toggle or a motor operator.

Power frame switches are larger, faster and more powerful than molded case switches, and are capable of handling up to 5, amps. A two-step stored energy technology is utilized that permits manual and electrical operation under load. For three-phase power applications requiring that the neutral conductor be switched, transfer switches can be configured with a fully-rated fourth pole that performs identically to the individual phase A, B, C power poles.

For single-phase applications, a fully-rated third pole can be configured. A switched neutral is commonly used when the transfer switch is fed by separately derived power sources. For simplified maintenance and improved uptime, bypass isolation automatic transfer switches provide dual switching functionality and redundancy for critical applications.

The primary ATS handles the day-to-day distribution of electrical power to the load, while the bypass switch serves as a backup or redundant device. A bypass isolation transfer switch is frequently selected for use in healthcare and other critical applications because it allows the ATS, and in some cases the bypass switch, to be drawn out and isolated from the power source s to facilitate regular maintenance, inspection and testing as prescribed by code NFPA Facilities with a single utility connection and a single emergency power source will often have an ATS located at the service entrance to ensure that critical loads can quickly and safely shift to emergency power if utility power is interrupted.

Non-critical loads are often inhibited or shed from connection to the emergency power source to avoid capacity overload. When applying a transfer switch for use in a power distribution system consideration must be given to the withstand closing current rating WCR to ensure system integrity and reliability. Transfer switches with multiple ratings provide greater application flexibility. Learn about the Eaton Power Systems Experience Center PSEC - a training facility where engineers and electricians can see the latest advances in electrical power quality, energy management and safety, and test products in a safe environment.

Electrical safety requires periodic testing and maintenance for switchgear, breakers, transformers and electrical equipment. Learn about ductor, megger, hi-pot and typical electrical testing methods at Eaton's Experience Center. Automatic transfer switches. Fundamentals of automatic transfer switches ATS. What is an Automatic Transfer Switch? Low-voltage automatic transfer switch assemblies provide a reliable means of transferring essential load connections between primary and alternate sources of electrical power.

Data centers, hospitals, factories and a wide range of other facility types that require continuous or near-continuous uptime typically utilize an emergency alternate power source such as a generator or a backup utility feed when their normal primary power source becomes unavailable. Learn more. How does an automatic transfer switch work? A typical transfer sequence includes:.