A 24v relay is a great way to control electrical equipment that requires high current. It can be used to switch on and off many different types of power, including AC mains electricity. These relays are also commonly used in motors, pumps, lights and other appliances.
How to Wire a 24v Relay
In simple terms, a relay is an electromechanical switch that works by activating an electromagnetic coil to make or break a set of contacts. This makes it a very useful piece of kit in applications such as home automation, motor control and so on.
The most basic type of relay consists of two parts: a coil and one or more sets of contact terminals. When a control signal is applied to the coil a magnetic field is generated around it and this pulls the hinged armature down onto the contacts which completes the high current circuit between the terminals.
When a control signal is removed from the coil, a spring pulls the armature back into its ‘at rest’ position which breaks the circuit between the terminals and this prevents the coil from being activated again. This is called the’make or break’ effect and it is important to note that this can occur even when the coil has no power on it.
There are several different types of relays but most are commonly known as a 4 pin or 5 pin relay. They have 2 pins (85 and 86) that connect to the coil and 2 pins (30 and 87) that switch power on or off a circuit. They are available in both normally open and normally closed configurations.
Using a Multi-meter
To test a relay, you should first remove power from the coil and then check each of the switch terminals for either continuity or resistance by running a meter probe over them. You should be able to hear a beep or read a digital reading when there is a connection, so you can be sure that the coil is good and that the switch is in the correct position as per its label.
If the switch is in the wrong position, then you should power the coil again and repeat the testing. If this is the case, then it is likely that there is something wrong with the switch itself.
The best place to start would be with the terminal diagram on the front of a relay. This will show the internal circuits and help you to understand how a particular relay will work.
You can then use this diagram to create your own wiring scheme. Remember that the relay is only a part of the overall circuit and that you will need to use other components in order to make your wiring scheme work.
The most common relays for use in auto and marine applications are those that consist of 4 or 5 pins, although there are also some more specialist models available with 9 pins. These more complex relays are designed to handle higher voltage and power, often for controlling starter motors or other solenoids. They can be supplied in 12V, 6V and 24V versions, with some having wider terminal widths than standard.
