Safety relay PNOZ s5 C 24VDC 2 n/o 2 n/o t 751105

Functionality and Application in Safety Systems

The PNOZ sigma series relay, model PNOZ s5 C, is a standalone control module designed to monitor critical safety functions in machines and production lines. The device operates on a 24 V DC supply voltage and enables the implementation of advanced stop scenarios, including monitoring of emergency stop buttons (E-STOP), safety gates, and light curtains. A key feature of this model is the ability to configure inputs as either single-channel or dual-channel circuits, with the option to detect cross-channel short circuits. This allows the installer to adapt the circuit to the specific requirements of the EN ISO 13849-1 standard, achieving Safety Integrity Level PL e and Category 4.

The device stands out for its temporal flexibility, which is particularly useful in processes requiring controlled deceleration of drives before complete power disconnection. The use of delayed contacts helps avoid abrupt stops that could damage machine mechanics or pose a risk to the operator.

Output Configuration and Integration Capabilities

The output structure of this relay is designed to cover most typical needs in industrial automation. The module features a total of four safety outputs:

• Two immediate outputs (2 n/o): These activate immediately upon safety function triggering, which is essential for quickly disconnecting power to actuators or motors (in accordance with Stop Category 0).
• Two delayed outputs (2 n/o t): The delay time can be adjusted over a wide range from 0.04 s to 300 s. This enables the creation of a "soft stop" stop sequence or allows additional actions to be performed before fully shutting down the machine (Stop Category 1).
• One semiconductor signaling output: This is a 24 V DC transistor output of type F (Frequency Generator) or R (Rotation Detector), enabling connection of the relay to higher-level control systems (e.g., PLC) for monitoring the device status without loading safety circuits with high currents.

It is worth noting that the ability to select the operating mode – manual or automatic reset – provides great flexibility in designing the machine's control logic. In the event of a fault or sensor activation, the operator can choose the appropriate method to restore system operation, thereby increasing the safety of the startup process.

Mechanical Construction and Operating Conditions

The device is mounted on a standard 35 mm DIN rail thanks to its compact housing with a width of only 22.5 mm. This small size allows for optimal use of space in control cabinets, where every centimeter counts. Electrical connections are made using "push-in" spring terminals, which significantly accelerate the installation process and eliminate the risk of wire loosening due to vibrations – a common issue in industrial environments. These terminals are also plug-in replaceable, facilitating module replacement in case of failure without the need to disconnect wires from the cabinet.

The device is designed for operation in typical production hall conditions, where ambient temperature can range from -10°C to +55°C. The housing provides an IP40 degree of protection against solid objects larger than 1 mm, and surge immunity class III / II according to EN 60947-1 ensures resistance to electromagnetic interference. The electrical parameters of the contacts are adapted to standard industrial loads – at AC-15 voltage, the relay handles a current up to 3 A at 230 V, while in DC-13 circuits this capability increases to 6 A at 24 V DC. For AC-1 and DC-1 loads, the maximum current is also 6 A at corresponding voltages up to 240 V AC or 24 V DC. Thanks to TÜV certifications and compliance with EN IEC 62061 (SIL CL 3) and EN ISO 13849-1 (PL e) standards, this relay constitutes a reliable link in systems protecting people and property, meeting the rigorous requirements of modern machinery legislation.