A DPDT relay (Double Pole Double Throw) is a type of switch that can control two separate circuits with a single control signal. It is commonly used in industrial control applications, and is often found in electrical panels and control cabinets. The 8-pin DPDT relay is a popular type of relay that is easy to wire and can be used for a variety of applications.
What is a DPDT Relay?
A DPDT relay consists of two separate switches that are activated by a single control signal. Each switch has two positions, and can be used to control two separate circuits. When the relay is activated, one switch is closed and the other is open. When the relay is deactivated, the opposite switch is closed and the other is open. This allows the relay to control two separate circuits with a single control signal.
DPDT relays are commonly used in industrial control applications, such as for controlling motors, valves, and other electrical devices. They are also used in control cabinets and electrical panels.
Wiring a DPDT Relay
Wiring a DPDT relay is relatively simple, and can be done with a few basic tools. The relay has eight pins, which are labeled as follows:
| Pin | Label |
|---|---|
| 1 | Coil |
| 2 | NC (Normally Closed) contact 1 |
| 3 | NO (Normally Open) contact 1 |
| 4 | Common contact 1 |
| 5 | Common contact 2 |
| 6 | NO contact 2 |
| 7 | NC contact 2 |
| 8 | Coil |
To wire a DPDT relay, follow these steps:
Step 1: Identify the Control Signal
The first step in wiring a DPDT relay is to identify the control signal. This is the signal that will activate the relay and control the two separate circuits. The control signal can be a voltage, current, or a signal from a controller or PLC.
Step 2: Connect the Control Signal
The control signal should be connected to pins 1 and 8 on the relay. These are the coil pins, and the control signal should be connected across them.
Step 3: Connect the Common Contacts
The common contacts on the relay are pins 4 and 5. These contacts are connected to the common terminals of the two circuits that are being controlled by the relay.
Step 4: Connect the Normally Open Contacts
The normally open contacts on the relay are pins 3 and 6. These contacts are connected to the positive terminals of the two circuits that are being controlled by the relay.
Step 5: Connect the Normally Closed Contacts
The normally closed contacts on the relay are pins 2 and 7. These contacts are connected to the negative terminals of the two circuits that are being controlled by the relay.
Applications of DPDT Relays
DPDT relays can be used for a variety of applications where two separate circuits need to be controlled with a single control signal. Some common applications of DPDT relays include:
- Controlling motors
- Controlling valves
- Controlling lamps and lights
- Controlling fans and blowers
- Controlling heating elements
Frequently Asked Questions
What is the difference between a DPDT relay and a SPDT relay?
A DPDT relay has two sets of contacts, and can control two separate circuits with a single control signal. A SPDT relay (Single Pole Double Throw) has one set of contacts, and can only control one circuit.
How do I know if I need a DPDT relay for my application?
If you need to control two separate circuits with a single control signal, then you will likely need a DPDT relay. If you only need to control one circuit, then a SPDT relay may be sufficient.
Can I use a DPDT relay to control AC circuits?
Yes, DPDT relays can be used to control both AC and DC circuits. However, it is important to make sure that the relay is rated for the voltage and current of the circuits being controlled.
Can I wire a DPDT relay in reverse?
Yes, DPDT relays can be wired in reverse, so that the normally closed contacts are used as the normally open contacts, and vice versa. This can be useful in certain applications, such as for reversing the direction of a motor.
