Relays are a great way to control circuits without the need for high rated switches or heavy gauge cable. They are also very useful in automotive applications as they can be installed anywhere in a vehicle to provide effective power transfer between electrical accessories.
How to Wire a 5 Pin Relay
When you first buy a relay, it is essential that you know how to wire it correctly so that you can use it effectively. A good place to start is by reading the product specifications or a datasheet that is provided with the relay. This will give you an idea of how to connect the terminals to other components.
Step 1: Identify the 5 pins on the relay.
The five pins on a relay are pin 1, comms (COM), pin 2, normally open (NO), pin 3 and pin 4. When the relay is not energized, pin 1 will be connected to either pin 2 or 3. In order for the relay to operate correctly, you need to connect the COM pin to the device you want to control by connecting a cable from this pin to its input.
Step 2: Determine the voltage rating of the relay.
Most 5 pin relays have a standard voltage rating of 12V or 24V. This means that they will switch power on and off at the rated rate when energised by a power source. The higher the voltage, the more powerful the relay.
Step 3: Test the coil.
A relay coil is a copper wire that is wound in a magnetic coil to switch power on and off. The coil can be energised by either an AC mains voltage or a DC voltage. You can check the coil on a relay by using a multimeter or voltage tester.
Step 4: Test the switching of the relay.
A common method of testing a relay is to connect the leads of a multimeter to the switch pins. The multimeter should show a high resistance when the relay is energized and a low resistance when it is de-energized.
Step 5: Check the current rating of the relay.
Relays with a coil can produce extremely high voltages when they are energised. This can damage sensitive electronic devices upstream of the relay coil and it is often recommended that a diode be used across the coil to dissipate these spikes.
The diode should be installed with the stripe facing towards terminal 86 on the relay body so that it is reverse biased. This will prevent any damage to the coil when it is energised by an alarm output signal which is commonly taken from an upstream control module.
Lastly, you should check the insulation resistance of the relay. This is a very important part of the relay test process and should be done before any wiring is completed. The insulation resistance should be more than 1000 ohms to ensure that the relay is working properly.
