Safety relay PNOZ s4 24VDC 3 NO 1 NC 750104

Safe Control in a Compact Housing

The PNOZsigma series device, model 750104, is a safety relay designed to monitor critical functions in industrial machines and systems. Its primary task is to supervise emergency stop (E-STOP) circuits, safety gates, and optoelectronic devices such as light curtains. Thanks to the use of 24 V DC control voltage, this module integrates perfectly with modern control cabinets, offering high reliability while maintaining a narrow housing with a width of only 22.5 mm. Such dimensions allow for space savings in distribution boards, which is crucial in dense automation component mounting.

Contact Configuration and Mounting Flexibility

The interior of the device offers a precisely selected output configuration that covers most standard applications in safety automation. It includes 3 safety contacts of the NO (normally open) type, which provide direct power disconnection to drives in hazardous situations. Additionally, the device is equipped with 1 auxiliary contact of the NC (normally closed) type and 1 semiconductor output, which can be used for status signaling or controlling other logic modules. This arrangement allows simultaneous machine shutdown and signal transmission to the supervisory system without the need for additional intermediate relays.

Mounting is performed on a DIN rail, facilitating quick installation and removal during maintenance work. Electrical connections are made using screw-type plug-in terminals, which ensure secure fastening of conductors with a cross-section from 24 to 12 AWG. Such connectors are resistant to vibrations typical of industrial environments and eliminate the risk of conductor loosening during operation. The polycarbonate (PC) housing provides an IP40 protection class, protecting the interior against dust and water droplets falling at an angle, which is sufficient for most applications inside control cabinets.

Compliance with Standards and Operating Conditions

The device meets rigorous functional safety requirements, achieving Safety Category 4 according to EN 954-1 and Performance Level PL e according to EN ISO 13849-1. This means that even in the event of a single internal fault, the system retains the ability to safely shut down the machine. The manufacturer has obtained numerous international certificates, including from TÜV, UL (cULus Listed), and KOSHA, confirming its suitability for projects implemented in European, American, and Asian markets.

Device operation is possible at an ambient temperature from -10°C to +55°C, and relative humidity can reach up to 93% (at 40°C), provided there is no condensation of water vapor on contact elements. The contacts are made of silver-copper-nickel alloy (AgCuNi) with a gold plating thickness of 0.2 µm, ensuring low contact resistance and long service life even with frequent switching cycles. The maximum current switched by the safety contacts is 6 A for AC/DC voltage (depending on the load category), allowing direct control of contactors or smaller motors without additional intermediate relays.

Thanks to the ability to configure inputs as single- or dual-channel and the option for inter-channel short-circuit detection, the device adapts to various safety sensor wiring schemes. Manual or automatic reset modes allow flexible management of the machine restart process after hazard removal. The entire construction has been designed to minimize the risk of installation errors and ensure continuous system operation even under difficult environmental conditions.