SSR relay with heatsink for DIN rail 30A, zero-cross switching, control 24V DC 77.31.9.024.8050

Contactless Control of High-Current Resistive Circuits

In industrial applications where frequent switching of high-power loads is required, traditional mechanical relays wear out quickly due to contact arcing. The solution to this problem is a modular solid-state relay (SSR) with a built-in heatsink, which eliminates moving parts and ensures reliable operation even at high switching frequencies. This device, designed for direct mounting on a 35 mm DIN rail, enables smooth current control up to 30 A in AC circuits, making it an ideal choice for controlling electric heaters, electromagnetic valves, or contactor coils.

A key feature of this model is the implementation of Zero Crossing switching technology. This means that the conduction state changes precisely when the mains voltage passes through zero. This solution eliminates sudden current surges (so-called inrush current), which could damage delicate load components or interfere with other devices in the installation. This is particularly important when controlling compact fluorescent lamps or high-power LED bulbs, where traditional switching could lead to premature burnout.

Application and Mounting Flexibility

The device has been designed for easy integration into modern control cabinets. Its compact modular construction saves space in the distribution board, and the integrated heatsink eliminates the need to purchase external cooling components for currents up to 30 A. The control input operates within a DC voltage range of 4 V to 32 V DC (with a nominal 24 V), enabling direct connection to PLC outputs, building automation systems, or simple logic circuits without the need for additional intermediate relays.

Thanks to the use of a single switching contact (1Z) and single-phase operation, this model is suitable for simple single-phase control circuits. The rated load voltage covers a wide range from 48 V AC up to 480 V AC, providing great flexibility when designing installations with different mains voltage levels. An operation indicator in the form of a green LED allows for quick and intuitive checking of the relay status during system diagnostics without the need to remove the device from the rail.

Benefits of Solid-State Construction

Choosing this type of relay brings tangible benefits for both the installer performing the installation and the end-user concerned with the longevity of the installation:

• No arcing and noise: Due to the absence of mechanical contacts, the device operates completely silently and does not generate electromagnetic interference during circuit switching.
• Longevity: The lifecycle is based on millions of switching operations, which is unattainable for electromechanical relays during frequent cyclic switching of heaters or fans.
• Surge protection: Zero Crossing switching technology minimizes thermal stress on connected loads, extending their service life.
• Easy installation: The standard module width allows for quick mounting on a DIN rail without the need for specialized tools or additional mounting brackets.

The device is intended for resistive loads (category AC-1) and operates in single-phase circuits. The control voltage is DC, and the output voltage range meets the needs of most standard industrial and commercial installations. It is worth noting that although the device has a built-in heatsink, its thermal performance depends on ambient conditions and airflow within the distribution cabinet. In the case of continuous operation at maximum load current, adequate ventilation of the room or control cabinet must be ensured to maintain the temperature within safe limits and guarantee stable operation throughout the entire service life.