PILZ 777949 PSWZ X1P Standstill Monitoring Safety Relay

The PILZ 777949 PSWZ X1P is a high-performance standalone safety relay purpose-built for safe standstill monitoring in industrial machinery and automation systems. Designed for use in safety circuits in accordance with EN 60204-1 and IEC 60204-1, this device provides reliable protection against hazardous machine motion by continuously monitoring the electromotive force (EMF) generated when motors coast down. When the monitored voltage falls below the set response threshold, the safety outputs are activated, indicating that the machine has reached a safe standstill condition.

Standstill Monitoring Function

The PSWZ X1P monitors zero-speed conditions by measuring the back EMF voltage induced in the motor windings during the coast-down period. Unlike conventional speed monitoring methods that require external sensors, this relay operates without the need for additional encoders or proximity switches, using two separate measuring channels to evaluate the regenerated voltage. When the measured voltage drops below the adjustable response threshold (0.02-0.5 V AC/DC), the device confirms standstill and enables subsequent safety operations such as access to hazardous areas or maintenance procedures on dangerous machine parts or tools. The maximum measurable changeover voltage is 690 V, accommodating a wide range of motor sizes and drive configurations, making it particularly suitable for inverter-driven applications.

Key Features

• Universal Power Supply: Wide operating voltage range of 24-240 V AC/DC eliminates the need for multiple relay variants

• Adjustable Response Threshold: Measured changeover voltage (UM) settable from 0.02 V to 0.5 V AC/DC

• Dual-Channel Input Wiring: Supports both 1-channel and 2-channel connection modes for enhanced safety integrity

• Built-in Self-Monitoring: Integrated self-diagnostics ensure reliable fault detection and safe operation

• Direct Drive Inverter Compatibility: Can be used directly with inverter drives without requiring external sensors

• LED Status Indication: Visual indicators for power, channel status, and output conditions

Technical Specifications

Output Ratings

Safety Standards and Approvals

The PSWZ X1P 777949 complies with stringent international safety standards. It holds approvals including CCC, CE, UKCA, cULus Listed, TÜV, and EAC (Eurasian). The standalone safety switching device is rated for Category 4 performance level according to EN 954-1 and is suitable for safety functions requiring a feedback loop. Its built-in self-monitoring ensures that any internal fault results in a safe state, making it a reliable component for safety-critical applications.

Applications

• Standstill monitoring on plants with dangerous machine parts or tools

• Safety circuits for machines with hazardous rotating components

• Machinery requiring zero-speed verification before access

• Inverter-driven motor systems without external encoders

• Industrial equipment compliant with EN 60204-1 and IEC 60204-1 safety requirements

Installation and Operation

The PSWZ X1P features removable clamps for convenient wiring and maintenance access. Its compact 45 mm width makes it suitable for space-constrained control cabinets while providing full safety functionality. The device supports single-channel and dual-channel wiring configurations, allowing system designers to select the appropriate safety integrity level for each application. For applications requiring higher availability, the relay includes a feedback loop that can be used to monitor external contactors and other safety devices, ensuring comprehensive safety circuit integration.