Power Supply Module in PLC

PLCs are powered by standard commercial AC power lines. However, many PLC components, such as the CPU and memory, utilize 5 volts or another level of DC power.

The Power Supply Module in PLC converts AC power into DC power to support those components of the PLC.


The power supply module is an essential component in a Programmable Logic Controller (PLC) system. It is responsible for providing the necessary electrical power to the PLC and its associated modules, ensuring their proper functioning.

Here are some key points about the power supply module in a PLC:

Power Input

The power supply module typically accepts an input voltage from the main power source, which can vary depending on the specific model and application. Common input voltage options include 110V AC, 220V AC, or 24V DC.

Voltage Regulation

The power supply module regulates the input voltage to provide a stable and consistent output voltage. This is crucial for the reliable operation of the PLC and its connected devices. The output voltage is usually specified by the manufacturer and can be either DC or AC, depending on the requirements of the PLC system.

Current Capacity

The power supply module has a specific current capacity, which indicates the maximum amount of electrical current it can deliver to the PLC system. It is important to select a power supply module that can handle the current requirements of the PLC and all the connected modules, including input/output (I/O) modules, communication modules, and other peripheral devices.


Some PLC systems may include redundant power supply modules to ensure continuous operation in case of a power supply failure. Redundant power supplies provide backup power and automatically switch to the backup module if the primary module fails. This helps to enhance system reliability and minimize downtime.

Overload and Short Circuit Protection

The power supply module often incorporates protection mechanisms such as overload protection and short circuit protection. These features help to prevent damage to the power supply module and the connected components in case of excessive current or short circuit conditions.

Diagnostic Indicators

Many power supply modules include diagnostic indicators such as LED lights or digital displays. These indicators provide information about the status and health of the power supply module, such as input voltage status, output voltage status, and fault conditions. This aids in troubleshooting and maintenance of the PLC system.

Mounting and Installation

The power supply module is typically designed for easy mounting and installation within the PLC panel or rack. It may include features such as DIN rail mounting or specific connectors for easy integration with other PLC components.

It is important to choose a power supply module that is compatible with the PLC system’s voltage and current requirements. Proper sizing and selection of the power supply module are crucial to ensure reliable and stable operation of the PLC and its associated devices. Consulting the PLC manufacturer’s specifications and guidelines is recommended when selecting and installing the power supply module.