Relays are an essential component in modern electrical systems, used to control high-power circuits with low-power signals. They provide a safe and reliable way to switch loads on and off, and can be used in a wide range of applications. A 4 terminal relay is a type of relay that has four terminals, each of which has a unique function in the wiring diagram. In this article, we will discuss the 4 terminal relay wiring diagram in detail, including its components, operation, and applications.
Overview of a 4 Terminal Relay
A relay is an electromagnetic switch that uses an actuating signal to control an electrical circuit. It consists of a coil, a set of contacts, and a spring-loaded armature. When the coil is energized, the armature moves to close the contacts, allowing current to flow through the load. When the coil is de-energized, the armature moves back to its resting position, opening the contacts and interrupting the circuit. A 4 terminal relay has four terminals: two for the coil and two for the contacts.
Components of a 4 Terminal Relay
A 4 terminal relay consists of the following components:
| Component | Function |
|---|---|
| Coil | Creates a magnetic field when energized, which pulls the armature towards the contacts. |
| Contacts | Switches the load on and off when the relay is energized and de-energized. |
| Armature | Moves towards the contacts when the coil is energized, closing the circuit. |
| Spring | Returns the armature to its resting position when the coil is de-energized, opening the circuit. |
Wiring Diagram for a 4 Terminal Relay
A 4 terminal relay wiring diagram shows how to connect the relay to the load and the signal source. The wiring diagram will typically include the following components:
Load: The device that the relay will control.
Power source: The source of power that will energize the coil.
Ground: The circuit that connects to the negative terminal of the power source.
Signal source: The low-power signal that activates the relay.
Here is an example of a 4 terminal relay wiring diagram:
Terminal 1 and Terminal 3
Terminal 1 and Terminal 3 are the coil terminals of the 4 terminal relay. The coil terminals are usually marked as 85 and 86 on the relay, but can also be marked as A1 and A2. These terminals are used to apply power to the coil of the relay. When voltage is applied to one of the coil terminals, a magnetic field is generated in the coil, which pulls the armature towards the contacts.
The polarity of the power supply is not important, as long as the correct voltage is applied. A typical voltage range for a 4 terminal relay is 12-24V DC or 24-240V AC. The rated coil voltage will be specified on the relay datasheet.
Terminal 2 and Terminal 4
Terminal 2 and Terminal 4 are the contact terminals of the 4 terminal relay. The contact terminals are usually marked as 30 and 87 on the relay, but can also be marked as C and NO (Normally Open). These terminals are used to switch the load on and off when the relay is energized and de-energized.
Terminal 2 is the common (COM) terminal, which is always connected to the load. It is usually connected to the positive terminal of the load, but can also be connected to the negative terminal, depending on the circuit configuration. Terminal 4 is the Normally Open (NO) terminal, which is connected to the load when the relay is energized. When the relay is de-energized, terminal 4 is open and the load is disconnected.
Applications of a 4 Terminal Relay
4 terminal relays are commonly used in automotive, industrial, and household applications, where a low-power signal is used to control a high-power circuit. Some common applications of a 4 terminal relay include:
- Automotive lighting and horn systems
- Industrial machines and equipment
- Household appliances and lighting systems
FAQ
What is a 4 terminal relay?
A 4 terminal relay is a type of relay that has four terminals, each of which has a unique function in the wiring diagram. It is used to control high-power circuits with low-power signals, and can be used in a wide range of applications.
What are the components of a 4 terminal relay?
A 4 terminal relay consists of a coil, a set of contacts, an armature, and a spring. The coil creates a magnetic field when energized, which pulls the armature towards the contacts. The contacts switch the load on and off when the relay is energized and de-energized. The spring returns the armature to its resting position when the coil is de-energized.
How do I wire a 4 terminal relay?
A 4 terminal relay can be wired by connecting the coil terminals to a power source and ground, and connecting the contact terminals to the load and signal source. The wiring diagram will typically include the load, power source, ground, and signal source. The polarity of the power supply is not important, as long as the correct voltage is applied.
What are the applications of a 4 terminal relay?
4 terminal relays are commonly used in automotive, industrial, and household applications, where a low-power signal is used to control a high-power circuit. Some common applications of a 4 terminal relay include automotive lighting and horn systems, industrial machines and equipment, and household appliances and lighting systems.
