Sunday July 25, 2021

updated - July 25, 2021 Sunday EDT

How Do Electrical Relays Work?

Jul 30, 2020 08:54 AM EDT | By Staff Reporter
How Do Electrical Relays Work?
(Photo : pixabay)

Do you know some switches can open and close electrical circuits electronically or electromechanically? These are widely recognized as relays. They control the functions of the contacts on another channel. Relays help in moving smaller amounts of current flowing through a control circuit in small motors that draw low amps. They also have an amplifying effect of controlling larger amperes and voltages. These switches prevent appliance damage by identifying electrical abnormalities, such as overloads, reverse currents, undercurrent, and overcurrent. Some of the relays can also switch heating elements, audible alarms, pilot lights, and starting coils.

Parts of relays

The different parts of electrical relays are as follows:

  • Frame - The heavy-duty frame contains all the parts of a relay.
  • Coil - The coil around a metal core causes the electromagnetic field that helps in opening and closing circuits.
  • Contacts - It is the conducting part that opens or closes a circuit.
  • Armature - It is the only moving part of a relay. There is also a spring attached in the relay that lets the armature return to its original position.

There are two circuits on which relays work: contact circuit and energizing circuit. Current flows through a coil to generate the magnetic field right after the relay coil gets energized. It doesn't matter whether you are using a relay on an AC or DC unit. The primary function doesn't change.

A contact unit sends electrical signals to relays. The contact unit contains an electromagnet that creates a magnetic field with the help of electric current. Once you activate this electromagnet, the combination of current and voltage in the wire opens or closes the contact.

Configuration of contacts

Contacts come in various configurations. They are crucial for relays to work smoothly. The connections depend on many factors like poles, throws, and breaks that make up a relay. You will often come across relays termed as double-pole, single-throw (SPST), single-throw (DPST), or single-pole. They indicate the function and design of different relays.

1. Pole - These consist of isolated circuits where relays pass through a switch. Single-pole contacts carry current via a single channel at one time. You can increase the number of connections to ensure that the pole can carry current via multiple circuits simultaneously. But you can't add more than 12 poles in an isolated circuit.

2. Break - A switch uses multiple contacts while opening or closing an electrical circuit. The connections either come in a single or double break system. Separate brake systems consist of breaks in only one place. They are widely used while switching lower-power devices like indicating lights. Dual break systems, on the other hand, find their way into high-power devices like solenoids.

3. Throw - This indicates the number of closed contacts that a pole contains in a switch. Switches with a single throw can regulate one circuit only while double-throws can control two channels simultaneously.

It's essential to use relays in electrical circuits as they protect your electrical appliances. Talk to a professional electrician regarding the installation of relays and prevent potential damage.

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