How Does 5 Pin Relay Work?

Key Takeaway

A 5 pin relay works by using a small current to control a larger current. It has two pins (85 and 86) for the coil, and three pins (30, 87, and 87A) for switching power between circuits. When a voltage is applied to pins 85 and 86, the coil is energized, creating a magnetic field. This magnetic field moves the internal switch, connecting pin 30 to either pin 87 or 87A. Pin 87A is normally closed (connected to 30 when the relay is off), and pin 87 is normally open (connected to 30 when the relay is on). This setup allows you to control two different circuits with one Omron Relay.

Basic Configuration of 5 Pin Relays

A 5 pin relay is designed with five terminals: two for the coil (85 and 86) and three for the switch contacts (30, 87, and 87a). Terminal 30 is the common contact, which connects to the power source. Terminal 87 is the normally open (NO) contact, and terminal 87a is the normally closed (NC) contact. When the coil is energized by applying voltage across terminals 85 and 86, it creates a magnetic field that moves the internal switch, connecting terminal 30 to terminal 87 and disconnecting from terminal 87a.

Detailed Functionality: How 5 Pin Relays Operate

When voltage is applied to the coil terminals (85 and 86) of a 5 pin relay, an electromagnetic field is generated. This field pulls the internal switch mechanism, causing the common terminal (30) to move from the normally closed (NC) position (87a) to the normally open (NO) position (87). Essentially, this switching action allows the relay to control a higher power circuit using a low power signal, which is ideal for applications that require the isolation of different parts of a circuit.

In simpler terms, when the relay is energized, terminal 30 disconnects from terminal 87a and connects to terminal 87, completing the circuit and powering the connected device. When the voltage is removed from the coil, a spring mechanism returns the switch to its default state, reconnecting terminals 30 and 87a.

This functionality is crucial in scenarios where controlling high-power devices directly with low-power signals is necessary, such as in automotive and industrial applications. For instance, in a car, this mechanism can be used to control the headlights, ensuring that the dashboard switch only handles a low current, while the relay manages the high current needed to power the headlights. This design not only improves safety but also enhances the longevity of the control switches.

By understanding the detailed functionality of 5 pin relays, engineers and technicians can better design and troubleshoot circuits, ensuring reliable and efficient operation of various electrical systems. This knowledge is essential for maintaining system integrity and performance in both automotive and industrial applications.

Common Uses of 5 Pin Relays in Automotive and Industrial Applications

In automotive applications, 5 pin relays are essential for controlling high-power devices such as headlights, horns, and fuel pumps. These relays allow a low-power switch to control a high-power circuit, preventing excessive current from flowing through dashboard switches and reducing the risk of overheating and damage. For instance, when you turn on your car’s headlights, a small current from the dashboard switch activates the relay, which then connects a higher current from the battery to the headlights.

In industrial settings, 5 pin relays are used to control machinery, motors, and other heavy equipment. They enable precise control and isolation of electrical circuits, ensuring safety and reliability. For example, a relay can be used to start and stop a motor based on signals from a control system, providing a safe and efficient way to manage industrial processes. Their robust design and versatility make 5 pin relays indispensable in both automotive and industrial applications.

Wiring a 5 Pin Relay: Step-by-Step Guide

Identify the Terminals: Locate the terminals 85, 86, 30, 87, and 87a on the relay. These numbers are usually printed on the relay housing or visible in the relay diagram.

Connect the Coil: Attach the power source to terminals 85 and 86. Typically, terminal 85 connects to the ground, and terminal 86 connects to the control switch or signal source. This setup energizes the coil when the control signal is active.

Common Terminal (30): Connect terminal 30 to the power source or the load you want to control. This terminal serves as the main power input that the relay will switch.

NO Contact (87): Connect terminal 87 to the device or load that should activate when the relay is energized. When the relay coil is powered, terminal 30 connects to terminal 87, powering the connected device.

NC Contact (87a): Connect terminal 87a to the device or load that should be active when the relay is not energized. This contact is normally closed, connecting terminal 30 to terminal 87a when the relay is not powered.

Test the Connections: Ensure all connections are secure. Test the relay by applying voltage to the coil terminals (85 and 86) to see if it switches correctly. The relay should activate the NO contact (87) and deactivate the NC contact (87a) when energized.

By following these steps, you can efficiently wire a 5 pin relay, ensuring reliable operation for your automotive or industrial applications.

Diagnostic Tips for Troubleshooting 5 Pin Relays

When troubleshooting a 5 pin relay, start by checking the coil resistance with a multimeter, as you would with a 5V 16 Channel Relay Module. The resistance should be within the specified range indicated in the relay’s datasheet. Next, inspect all wiring and connections for signs of damage, corrosion, or loose connections.

Verify that the control signal is reaching the relay coil by measuring the voltage across terminals 85 and 86. If the relay clicks but fails to switch the connected load, check the continuity between terminals 30 and 87 (NO) or 30 and 87a (NC).

When the relay is energized, terminal 30 should connect to terminal 87, and when de-energized, terminal 30 should connect to terminal 87a. Regular maintenance and testing can prevent issues such as contact pitting and coil burnout, ensuring reliable operation.

By following these diagnostic steps, you can effectively identify and resolve common relay issues, maintaining system reliability and performance.

Conclusion

5 pin relays are essential components in both automotive and industrial applications due to their ability to control high-power devices with low-power signals. Understanding their configuration, functionality, and proper wiring techniques ensures reliable operation and enhances the safety and efficiency of electrical systems. Regular diagnostics and maintenance help maintain their performance, making them invaluable tools for engineers and technicians. By leveraging the versatility of 5 pin relays, you can design robust and efficient control systems for a wide range of applications.