With the many different types of relay module configurations today, it can be difficult to know which one best suits your specific market or application. This guide will help you select the right relay module for your needs by explaining the different types of these devices.
Relay Module definition
The relay module definition first: A relay module is simply a relay that’s been packaged with a driver circuit to make it easier to control. The modular design allows it to hold several of these relays, each with its own circuit, and control several different circuits using one module.
Relay control modules are used in all sorts of applications, from controlling lights and motors to providing isolation between two circuits.
So you’ll find them installed in the electrical systems of homes, offices, commercial places, automotive, and even industrial facilities; virtually everywhere a lower power device is needed to control a higher power system.
Relay modules are manufactured in different sizes and with a host of different features. That means some applications may require specific types of relay module configurations. To acquaint you with the options for your relay module project, we compiled a list of the most common types.
Types of Relay Module Configurations
When it comes to switching power systems, different types of rely module configurations can be used. These range from NO (normally open) and NC (normally closed) relay modules to the optoisolated relay module and so on: More about them below.
1. Types of Relay Module by Number of Poles/Throws
Put simply, relay control module poles refer to the input connections while throws refer to the output or load terminals. The type to use in an application, therefore, mainly depends on the number of circuits to be controlled, among other factors. Options include the following: SPST, SPDT, DPST, DPDT configurations. The
SPST Relay Module
SPST stands for single-pole, single-throw. So the STSP relay module only has one pole that can control one circuit. The SPST module is the simplest type of relay module and is often used where only one device or power circuit needs to be switched on/off, such as a light.
SPDT Relay Module
The SPDT relay module is a single-pole, double-throw (SPDT) configuration. This means that it has one pole that can control two circuits. The SPDT module is the most common type and is often used to control things like lights or motors.
DPDT Relay Module
The DPDT relay module uses a double-pole, double-throw (DPDT) configuration. It has two poles, each of which can control two circuits. This type of relay module is often used in applications where two things need to be controlled independently.
DPST Relay Module
The DPST relay module, as its name suggests, uses a double-pole, single-throw (DPST) configuration. It contains two poles, but each can control only one circuit. The DPST module suits situations where two things need to be controlled but don’t have to be independent of each other.
2. Types of Relay Module by Number of Channels
Relay module channels refer to the number of individual relays that are packaged together in one unit. The most common options are the 1-channel relay module, 2-channel relay module, 4-channel relay module, and 8-channel relay module.
There are also other possible configurations that have not been, such as the 6-channel relay module and the 16-channel relay module, but these are much less common.
1-Channel Relay Module
A 1-channel relay module is a single relay that’s been mounted on the module or control circuit board. These modules are typically used to control one thing, such as a light. Because they only have one relay, the single-channel relay module types are usually the simplest and most affordable.
2-Channel Relay Module
A 2-channel relay module is a package containing two relays and their driver circuits. When using a relay module, 2 channel configurations make it possible to control two circuits with a single signal. These can be two lights or any other load.
4-Channel Relay Module
The 4-channel relay module is yet another common option and contains four relays. When used in an application, each relay can be controlled independently, making the module a good choice when four systems that needs to be controlled.
8-Channel Relay Module
An 8-channel relay module is one of the largest options when it comes to multi-channel modules. These modules are often used in applications where a lot of things need to be controlled at once. For example, you can use 5 volt relays in an 8 channel module to manage a series of lights.
3. Type of Relay Module By switch Type
A relay module may be a normally open type or it may use a normally closed configuration for its switching action. In a normally open configuration, the switch is open when the relay is off. In a normally closed configuration, the switch is closed when the relay is off.
Normal Open Relay Module
A normal open or NO relay module has a switch that’s typically open by default, or when the relay is off. When the relay is turned on, the switch closes, allowing current to flow. The NO configuration is often used in applications where it’s important to prevent a circuit from being energized until the relay is turned on.
Normal Closed Relay Module
A normal closed (NC) relay module has a switch that’s closed when the relay is off. When the relay is turned on, the switch opens, interrupting the flow of current. This type of relay module configuration suits applications where it’s required to occasionally switch on a device or system.
4. Other Types of Relay Modules
Relay modules are also distinguished by their voltage ratings and if they are opto-isolated with a photoelectric device or not. So you will often come across these types of relay module switching and control devices on the market.
Opto-Isolated Relay Module
An optocoupler uses light to isolate two electrical circuits. It’s usually an LED that emits light and a phototransistor that turns the light into current. An opto-isolated relay module uses the optocoupler principle to isolate the relay from the control circuit or input device.
Remote Control Relay Module
A remote control relay module includes a wireless communication interface that allows the relay to be controlled remotely. There are many options: It can be a Bluetooth relay module that uses a Bluetooth interface to receive commands or a Wi-Fi relay module that communicates with an IoT device via WiFi.
3.3V Relay Module
The 3.3V relay module is a less common type of the switching device. It’s designed for use with low-voltage circuits, such as those using 3.3V logic levels. These include ESP8266 and ESP32-based microcontrollers.
5V Relay Module
The 5V relay module is designed for use in circuits that use 5V logic levels. This type of voltage is common in Arduino and Raspberry Pi applications. These provide 5V control signals, which is high enough to activate the 5 volt relay module.
12V Relay Module
The 12V relay module is designed for use with circuits that use 12V logic levels, such as those used in automotive applications. Just like with other relays, the 12 volt relay module can be used to switch both AC and DC voltages.
24V Relay Module
The 24V relay module is designed for use with higher voltage circuits, such as those that use 24V logic levels. This type of voltage is often used in industrial applications. These include process control, machine automation, and power control systems.
Relay modules are available in a wide range of configurations to suit a variety of applications. These range from the simple, low-cost modules that use a single relay to more complex modules that use multiple relays or include features such as an optoisolator. The type of relay to use will, therefore, depend on the required features and capabilities, among other factors.