PILZ 774400 PDZ Safety Relay (PNOZ PDZ)

The PILZ 774400, also known as the PNOZ PDZ safety relay, is a universal safety module designed for emergency stop, safety gate, light curtain, and two-hand control applications. It operates on 24 V DC and provides three redundant safety outputs (2 NO + 1 NC) and one auxiliary output (NC). The unit meets the highest safety level PL e / SIL CL 3 and is housed in a 45 mm-wide plastic enclosure.

Functional Specifications

Supply voltage: 24 V DC (-15% / +20%), consumption 2.5 W. Inputs: single-channel or dual-channel (2 redundant paths), with cross-circuit detection. Response time: 20 ms typical. Safety outputs: 2 NO relays (6 A at 230 V AC, mechanical life 10 million cycles) and 1 NC relay (6 A). Semiconductor output: 1 PNP (24 V, 200 mA) for status signaling. The unit also has a start input configurable for automatic or monitored manual start.

Diagnostics and LEDs

LED indicators: Power (green), Input (green), Output (yellow), Fault (red). A flashing pattern on the fault LED indicates error type (e.g., short circuit between input channels, supply undervoltage). The relay stores the last four faults in non-volatile memory. A test pulse output (24 V, 5 ms) can be used to test external contactors.

Mechanical and Environmental

Dimensions: 45 mm x 100 mm x 120 mm (W x H x D). Weight: 0.3 kg. Mounting: DIN rail EN 60715. Protection rating: IP20. Operating temperature: -10°C to 55°C. Storage: -40°C to 85°C. Humidity: 93% non-condensing. Vibration resistance: 1 g (10-55 Hz). The terminals are screw type (accept 0.2-2.5 mm²). The housing is green to signify safety function.

Wiring Examples and Configuration

For emergency stop: connect the NC contacts of the E-stop button to S11 and S12 (channel 1) and S21 and S22 (channel 2). Jumper the start contact to Y1 and Y2 for automatic start. For safety gate with locking: additional feedback loop via the gate’s auxiliary contact to Y34. The relay can also be used with light curtains (OSSD outputs) by connecting to S11 and S21 with a jumper to create a manual reset circuit.

Applications and Standards

Commonly used in assembly stations, packaging machines, conveyor systems, and small robotic cells. The relay is certified to EN 60947-5-1, EN 60204-1, and UL 508. It has a high immunity to EMC (EN 61000-4-2, -4, -5). The 774400 PDZ is a direct replacement for older PNOZ 5 or PNOZ 7 models, with identical foot print for terminal screws.