The Difference Between an AC and DC Relay Coil

Relays are essentially electromagnets which also contain a spring-loaded lever which can switch over electrical contacts. In order to appropriately energize the relay, alternating current and direct current need to pass through the coil to answer the electromagnet which magnetizes the core and attracts the lever. The small current which is applied to the coil will switch the current in the circuit board.

The Main Uses

Relay coils are used like switches and we can find them in everything from furnace control units to streetlights to change over the power and to activate various properties on a device.

DC Relay

A DC relay offers a steady solution that never reverses and a DC relay will use a single coil of wire that is wound around an iron core making it electromagnet. While the current is flowing through a DC relay, the iron core loses its magnetism when the current is finally turned off the switch will be activated as the switch moves.

AC Relay

An alternating current will always stay the same and it never reverses the direction. As AC flows it will climb to a peak and then drop down to zero while it reverses the direction of flow. It’s during this dropping period that the magnetism goes back into the core. There are two coils in the transformer that can keep the core properly magnetized and make sure that the AC switch can change as soon as the power source is shut off.

Understanding the Type of power relay that’s required for your needs and making sure that you can get access to the ideal equipment for your business can be important. If you would like to learn more about the differences between AC and DC relay coils, contact us today to learn more.

This post was written by Justin Tidd, Director at Swartz Engineering. For nearly a half a century, Swartz Engineering has been at the forefront of industry safety. They are a family-owned company specializing in power distribution for the electrical industry. Our design ensures maximum flexibility for excellent reliability and a high return on investment.


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