Pilz PZE 9 Safety Relay – 3NO + 1NC Contacts

The Pilz PZE 9 is a force‑guided safety relay designed for emergency stop, safety gate, and two‑hand control applications. It monitors the state of external safety devices and, in the event of a fault, disconnects the machine’s safety circuit via its positively driven contacts. This model provides 3 normally open (NO) safety contacts and 1 normally closed (NC) auxiliary contact. It operates on a 24V DC supply and is certified to EN/ISO 13849‑1 up to PL e and IEC 61508 up to SIL 3. The PZE 9 is part of Pilz’s extensive safety relay range and is commonly used in machine control cabinets.

Technical Specifications

• Model: PZE 9 (also PZE9)

• Supply Voltage: 24V DC ±20%

• Power Consumption: 3.5 W typical

• Safety Contacts: 3 NO (force‑guided, each rated 6A at 230V AC)

• Auxiliary Contact: 1 NC (signal)

• Inputs: 2 channels for emergency stop or gate (with cross‑circuit detection)

• Reset Type: Automatic or manual (selectable by jumper)

• Response Time: 25 ms typical

• Operating Temperature: -10°C to +55°C

• Protection Rating: IP40 (housing), IP20 (terminals)

• Mounting: 35mm DIN rail

• Dimensions (W x H x D): 45mm x 100mm x 120mm

• Weight: 0.5 kg

Safety Circuit Design

The PZE 9 accepts dual‑channel input signals from emergency stop buttons (with positive‑opening contacts) or safety gate switches. It monitors for shorts between channels and to supply. The two input channels must be closed simultaneously for the relay to energize its safety outputs. If one channel opens, the output contacts open within 25 ms. The auxiliary NC contact changes state simultaneously and can be used to indicate the relay status to a PLC.

Force‑Guided Contact Technology

All safety contacts (3 NO) are mechanically linked (force‑guided) per EN 60947‑5‑1. This means that if any contact welds, the normally open contacts cannot close, and the normally closed auxiliary contact will not open, providing a reliable diagnostic indication. This feature is essential for building safety circuits up to Category 4.

Reset Modes

A jumper between terminals Y1 and Y2 selects reset mode: open = manual reset (push button required after input closure), closed = automatic reset (relay energizes as soon as inputs are closed). For manual reset, the reset button must be pressed for at least 50 ms. The reset input is monitored for shorts.

LED Indicators and Diagnostics

Front panel LEDs: PWR (green) – supply on, CH1 (green) – input channel 1 closed, CH2 (green) – input channel 2 closed, OUT (green) – safety contacts energized, FAULT (red) – cross‑circuit or mismatch detected. A flashing pattern on the FAULT LED indicates the specific error code.

Wiring and Installation

Use 0.5–2.5 mm² wire for terminals. For dual‑channel with cross‑circuit detection, connect E‑stop contacts to terminals S11/S12 (channel 1) and S21/S22 (channel 2). Connect the reset button to Y1/Y2 (if manual reset). The safety outputs are terminals 13‑14, 23‑24, and 33‑34 (all NO). The auxiliary NC contact is on terminals 41‑42. The relay must be mounted in a control cabinet with at least IP54 protection.

Safety Standards Compliance

The PZE 9 is certified by TÜV, UL, and CSA. It meets EN 60204‑1 (electrical equipment of machines), ISO 13849‑1 (PL e), IEC 61508 (SIL 3), and EN 62061 (SIL CL 3). It is also suitable for use in marine applications (DNV GL).

Typical Applications

Emergency stop circuits for packaging machines, conveyor systems, robotics cells, woodworking machinery, and printing presses. The relay is also used for guard door monitoring and two‑hand control panels.

Maintenance and Life

The relay has a mechanical life of 10 million operations and electrical life of 100,000 operations at rated load. No regular maintenance is required, but a functional test should be performed annually. In case of failure, the entire unit must be replaced.

Conclusion

The Pilz PZE 9 safety relay offers a compact, reliable solution for emergency stop and gate monitoring, combining high safety integrity with easy configuration and robust force‑guided contacts.