Phoenix Contact PSR-SCP-24DC/ESD/5X1/1X2/300 Safety Relay with Adjustable Time Delay

The Phoenix Contact PSR-SCP-24DC/ESD/5X1/1X2/300 (Order No. 2981428) is a safety relay from the PSRclassic series designed for emergency stop and safety door monitoring applications requiring configurable safety functions with adjustable output timing. This device supports functional safety up to SIL 3 according to IEC 61508/IEC 62061 and Category 4 Performance Level e according to EN ISO 13849-1 standards, enabling deployment in high-risk machinery safety applications requiring controlled shutdown sequencing.

Functional Capabilities and Input Modes

The safety relay supports both one-channel and two-channel operation modes, accommodating different safety circuit architectures. Two-channel operation with cross-circuit detection provides enhanced fault diagnostic coverage for safety gate monitoring applications. The device can be configured for automatic activation, where the safety outputs become active immediately upon closure of the input circuit, or for manual activation where a separate reset circuit must be closed to enable outputs after the input circuit is closed. This manual monitored start functionality prevents automatic machine restart after a power failure or after the safety circuit has been opened. The device is suitable for emergency stop circuits, safety door monitoring, and evaluation of light curtains in industrial equipment. Input circuit supports standard safety switching devices with mechanical contacts or OSSD outputs from light curtains and safety PLCs.

Output Configuration and Timing Functions

The PSR-SCP-24DC/ESD/5X1/1X2/300 features a mixed output configuration of timed and undelayed safety contacts. Three normally open (N/O) contacts provide undelayed switching, while two additional N/O contacts are configurable with a dropout delay ranging from 0.2 seconds to 300 seconds. The adjustable delay time can be set in 24 increments across this range, allowing precise matching to machine stop sequences or coast-down safety requirements. The delay applies only to the dropout (de-energization) of the timed outputs; the undelayed outputs drop out immediately upon safety circuit opening. One normally closed (N/C) auxiliary contact is provided for monitoring purposes, typically used to indicate relay state to a PLC or control system. Output contact configuration includes 5PST-NO and SPST-NC arrangement, with contact ratings suitable for switching safety contactors and other load devices.

Delay Time Configuration and Security

The adjustable delay time is set using the ESD-300 time setting element, which allows precise configuration across the 0.2 s to 300 s range. Protective labels are available to prevent accidental manipulation of the set time once configured, ensuring that safety-critical timing parameters remain fixed during operation. For applications requiring permanent protection, electronic protection against manipulation is available with PSR-ESD-30 models. This security feature is essential for safety applications where unauthorized changes to delay settings could create hazardous conditions or violate safety standards compliance. The time setting mechanism is designed to be accessible for configuration but securable against unintended adjustment through labeling or mechanical locking. The delay accuracy is maintained across the operating temperature range, ensuring consistent shutdown timing regardless of environmental conditions.

Electrical Specifications and Power Supply

The safety relay operates on a 24V DC supply voltage, with power consumption of approximately 3.72 W. The 24V DC input is the primary power source for internal logic, coil energization, and status indication. The contact switching voltage range spans from 5 to 250 V AC/DC, supporting both AC and DC loads on the output contacts. The device is designed for DIN rail mounting within a control cabinet environment. Plug-in screw terminal blocks are included for all field wiring connections, allowing module replacement without removing individual wires. Terminal size accepts standard industrial wiring gauges. The module includes LED indicators for power, input status, output state, and fault conditions, facilitating commissioning and troubleshooting.

Safety Integrity and Compliance

The PSR-SCP-24DC/ESD/5X1/1X2/300 is certified for functional safety applications with EN ISO 13849-1 PL e (Category 4) and IEC 61508/IEC 62061 SIL 3 ratings. The device meets requirements of EN 60947-5-1 for low-voltage switchgear and controlgear. Approvals include Functional Safety Approval ID 968/EZ408.05/23, UL Listed (FILE E 140324), cUL Listed (FILE E 140324), and EAC Approval ID TR_TS_D_00573_c. The product is also cULus Listed for use in North American installations. These certifications validate the device's suitability for safety-related applications in machinery and process industries worldwide. The relay meets EMC requirements for industrial environments, with immunity to electrical disturbances and limited emissions per applicable standards.

Environmental Ratings and Operation

Operating temperature range is specified for typical industrial control cabinet environments. The device is rated for use in industrial locations and complies with relevant EMC standards including immunity and emission requirements. The plastic housing is designed for DIN rail mounting and includes space for labeling and status indication LEDs. The PSRclassic series dimensions are 90 mm width for 24V DC models with time delay functionality. Humidity rating and pollution degree correspond to typical industrial control cabinet conditions, with the device requiring installation in an enclosure to protect against dust and moisture. The module meets vibration and shock resistance standards appropriate for machinery applications.

Typical Applications

This safety relay is suitable for applications requiring timed safety outputs following a safety circuit opening, such as monitored stopping of rotating machinery where the machine must coast to a stop before the guard can be opened. The adjustable delay allows tuning to the specific machine deceleration time. Other applications include sequential machine shutdown where energized components must be powered down in a specific order, safe control of pneumatic or hydraulic valves where delayed de-energization is needed to prevent dangerous states, and integration with light curtains where the machine motion must stop within a defined time before operator access is permitted. The ability to mix timed and undelayed outputs provides flexibility in safety system design, allowing immediate removal of power from hazardous energy sources while maintaining timing for ancillary functions such as cooling fans or lubrication pumps that must run for a defined period after a stop command.

Conclusion

The Phoenix Contact PSR-SCP-24DC/ESD/5X1/1X2/300 safety relay delivers adjustable timed safety outputs for emergency stop and safety gate applications. Its 24V DC supply, mixed undelayed and delayed contact configuration, and SIL3/PL e certification support machine safety systems requiring controlled shutdown timing.