Pilz 772120 PNOZ X2.8P Safety Relay Expansion Module

The Pilz 772120, also known as PNOZ X2.8P, is a safety relay expansion module from Pilz’s PNOZ X series. This unit is used to increase the number of safety contacts in a safety circuit, typically in combination with a base safety relay (such as PNOZ X1, X2, or X3). It allows monitoring of emergency stop buttons, safety gates, and light curtains with redundant output expansion.

Safety Contacts and Auxiliary Outputs

The module provides 2 normally open (NO) safety contacts, each rated at 6A (250V AC/24V DC), and 8 normally closed (NC) auxiliary contacts. The safety contacts are forced-guided according to EN 50205, ensuring reliable switching even under fault conditions. The auxiliary contacts can be used for status indication or reset circuits.

Safety Integrity Levels

The PNOZ X2.8P is suitable for applications up to category 4 (EN ISO 13849-1), PL e, and SIL CL 3 (IEC 62061) when used with a compatible base unit. It has a safe isolation of 250V AC between circuits and ground. The mean time to dangerous failure (MTTFd) is certified at >100 years.

Operating Principle

This expansion module does not have its own logic engine; it is controlled via a serial connection from a PNOZ X base relay. When the base relay energizes its internal coils, the expansion module’s safety contacts close simultaneously. The auxiliary contacts operate in opposite logic (NC open when safety contacts close). Wiring is accomplished via screw terminals.

Power and Mechanical

Operating voltage is 24V DC (from the base relay’s internal supply). Power consumption is 2 W. Dimensions are 96 x 80 x 48 mm. Mounting is on a 35 mm DIN rail (EN 60715). The unit is housed in a polycarbonate, UL94 V-0 rated casing. Operating temperature range: -10°C to 55°C.

LED Indication

A green LED indicates supply voltage and internal relay coil status. No state LEDs for individual contacts are provided. Diagnostic capability relies on the base relay’s fault indication.

Standards and Certifications

Compliant with EN 60947-5-1, EN 60204-1, UL 508, and CSA C22.2 No. 14. The module is CE marked and UKCA compliant. It is approved for use in machinery safety applications worldwide.

Applications

Used to add more safety output contacts to existing safety circuits, for example controlling multiple contactors or drives from a single emergency stop. Typical machines include presses, conveyors, packaging lines, and robotic cells.

Conclusion

The Pilz 772120 PNOZ X2.8P expansion module adds 2 safety contacts and 8 auxiliary contacts to PNOZ X base relays. Its forced-guided contacts and high safety integrity make it ideal for expanding safety output capacity.