The Laien SR4P2A1B24C is an emergency stop safety relay engineered to provide a reliable and certified safety interface for industrial machinery. Designed to monitor safety light curtains with NPN or PNP outputs as well as photoelectric two-hand control stations, this device forms a critical link in the functional safety chain. Its primary function is to continuously evaluate the status of connected safety devices and, upon detection of a fault or an intentional interruption, to de-energize its safety outputs, thereby bringing hazardous machine movements to a safe stop. Housed in a compact 22.5 mm wide DIN rail enclosure, the SR4P2A1B24C is an ideal solution for space-constrained control panels requiring high-integrity safety monitoring.

From a safety certification standpoint, the SR4P2A1B24C meets the highest international standards. It is certified to Performance Level e (PL e) and Safety Category 4 according to EN ISO 13849-1, and Safety Integrity Level 3 (SIL 3) according to IEC 61508. These certifications are supported by exceptional reliability metrics: a calculated Mean Time to Dangerous Failure (MTTFd) of 94 years and a Diagnostic Coverage (DCavg) exceeding 99%. This high diagnostic coverage is achieved through an integrated self-monitoring circuit that continuously verifies the integrity of internal components and wiring, ensuring that any potential failure is detected and the safety function is executed before a dangerous situation can arise.

The output stage of the SR4P2A1B24C provides two normally open (NO) safety contacts and one normally closed (NC) auxiliary contact for status feedback to a higher-level controller. The safety contacts are rated for 5 A at 250 V AC under AC-15 utilization category and 6 A at 24 V DC under DC-13, providing sufficient switching capacity for downstream contactors and power circuits. The device operates on a 24 V DC supply and consumes just 3 W of power. Its response time is under 15 milliseconds, ensuring swift execution of the safety function. The SR4P2A1B24C incorporates several key functional features, including detection of short-circuit faults across input contacts, user-selectable automatic or manually monitored reset modes, and real-time operational status indication.

The SR4P2A1B24C is designed for ease of integration and long-term reliability. It mounts on a standard DIN rail and measures 96 x 22.5 x 116 mm. The IP50-rated enclosure is suitable for installation in control cabinets with an ambient operating temperature range of -10°C to 55°C. The device complies with a comprehensive suite of international standards, including EN 60947-5-1, EN 61000-6-2/3, and IEC/EN 60204-1. With its combination of high-integrity safety certification, compact form factor, and robust electrical specifications, the Laien SR4P2A1B24C is a dependable core for safety circuits in packaging machinery, metalworking presses, automated assembly lines, and a wide range of general industrial automation applications.

Technical Specifications