Backup switch controller, 3 and 4-wire network, 24÷230V AC SZR-278

Intelligent power switching – controller SZR-278

The SZR-278 reserve power switchover controller is a reliable device designed for automatic switching between two power sources – main and backup. It ensures uninterrupted power supply in the event of a failure or parameter drop in the main network, protecting connected devices and processes. The device is compatible with both 3-wire and 4-wire networks, making it a universal solution for various installations.

Versatile application and parameter control

SZR-278 not only monitors the presence of voltage but also controls its quality. Built-in functions for monitoring phase sequence, phase asymmetry, and voltage (upper and lower threshold) ensure optimal protection of the electrical installation. Additionally, the controller has undervoltage and overvoltage control functions, which increase its effectiveness in protecting against network irregularities. This gives the installer confidence that the system is operating stably and safely, and the end user – that their devices are protected from damage caused by voltage fluctuations.

Flexibility and easy installation

The device, 6 modules wide (105 mm), is mounted on a standard 35 mm rail, making it easy to integrate with existing electrical infrastructure. Screw terminals with a cross-section of 2.5 mm² provide secure wire connections, and a tightening torque of 0.4 Nm guarantees connection stability. The controller does not require an external power source and consumes only 4 VA of power. The ability to adjust the line switching time (0.1÷5 s), generator start-up time (5÷100 s), and generator shutdown time (20÷200 s) allows for precise adjustment of the controller's operation to the specific needs of a given installation. Adjustable shutdown time (1÷15 s) and main input on-time after voltage recovery (5÷600 s) provide full control over the power switching process.