Last Updated on October 22, 2023 by Kevin Chen
Image source HP academy
Electromagnetic relays are commonly referred to as the relay devices. This is because in most applications they are used to control the flow and behavior of circuit. You are likely to find them in automatic control circuits where they control the flow of electric current.
An electromagnetic relay is a a type of switch that is electrically operated and responds due to the magnetic force, hence the combination of electricity and magnetism. This type of switch opens and closes thanks to the electromagnetic force.
Just like the manual switches, the act of opening and closing will allow or interrupt the flow of electric current.
This feature is vital in control systems such as those in power distribution, telecommunication, sensors among many other applications where a low-input signal is used to control the high-power circuit.
Are you building a product that will require the use of electromagnetic relays? Or, do you want to import electromagnetic relays in China? This is a perfect guide for you. We are going to break down everything that you should know about them.
Components of electromagnetic relay
Image source SPM physics
A typical electromagnetic relay comprises of the following key components:
This is the component responsible for generating the required magnetic forces. It is made up of a metal core and a coil of wire When electric current is passed through the circuit, the coil will be activated, creating a magnetic field. The magnetic force generated by the coil wire will attract the metal core resulting in some movement.
These are metal contacts which are also called armatures. They are attached to the metal core and respond and are designed to respond depending on the activities at the core. For instance, if the core is energized, the contacts will move to close the switch. When the core is de-energized, the contacts will move to break the circuit.
As we mentioned, this forms part of the electromagnet. Its function is to generate the electromagnetic field. It is connected to the voltage source and the number of coils will determine the strength and direction of the magnetic field.
Housing: This is a component that houses the whole electromagnetic relay device. It is mainly made of insulating materials and protects the inner components from physical and electrical damage.
Input and output terminals
For the electromagnetic relay to get the signals, it must be connected to the input and output terminals.
The input terminals is where the signals to the relay is applied and the output terminals is where the signals from the relays are channeled to the target circuit.
Whenever you buy an electromagnetic relay, inspect to ensure that all these components are in place.
Electromagnetic relay working principle
How does an electromagnetic relay work? To give you a clearer version of events, we have summarized all the steps that are involved in the working and operation of this relay.
Step 1: Input signal: It all starts at the input terminal, which is responsible for generating the input signal to the relay. The input signal is applied directly to the coil of the electromagnet. Usually, this signal is generated from a control system which always has low power.
Step 2. Activation of coil: Once the input signal has been supplied to the electromagnet, the next step is the full activation of the coil. This process entails generation of the magnetic field which will end up attracting the coil of the electromagnet. Usually, the strength of the magnetic field will depend on the current that comes into the coil from the input signal.
Step 3.Movement of the armature: The magnetic field generated at the coil will exert movement of the armature. This movement will determine the action of the switch whereby it can close or open depending on what the relay should do.
Step 4. Full switch operation: The operation of the switch is characterized by two metal metal contacts which are the fixed stationary contacts and the armature. The armatures will move to complete the circuit or break the circuit with the fixed metal contacts.
Step 5. Output channel: The output side of the relay is connected to an output circuit that has higher power. When the input relay is in a closed state, current will also flow to the output circuit. An open relay means that the flow of current to the output circuit will be interrupted.
Step 6. De-energization: This is the last stage of the the electromagnetic relay operation and happens when you cut off the input signal. The magnetic field will stop existing and the armature will assume its original position. Subsequently, the current will stop flowing to the output signal.
The above steps give a full summary of how the electromagnetic relay works. An action at the input signal will trigger reaction to the output circuit.
Technical parameters of electromagnetic relay
Here are the key technical parameters that you should know about electromagnetic relay before you buy one.
- Working voltage: You should check out the rated working voltage of this switching device. The rating can be AC or DC
- Pull-in current: This is the minimum current that is required to generate an action by the magnetic field. This current should not exceed 1.5 times the rated working voltage.
- Switching speed: This is time taken by the relay to switch from On-to Off state and vice versa. The speed should be high for sensitive applications.
- Drop-out voltage: This is the voltage point at which the armature will go back to its original position mainly because the magnetic field no longer exists.
- Pick-up voltage: This is the minium voltage that will be needed to close the relay. It is the minimum voltage that will be needed to generate a strong magnetic field.
Pay attention to these technical parameters as they they determine the overall performance of the electromagnetic relay. They also determine the suitability and compatibility of the relay to your application.
And in case you want to buy electromagnetic relay, ensure that you get from reliable and reputable sources. This way, you can be sure of the quality of products that you will end up with.
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