Omron SR125SMS4503 Stop Motion Sensing Unit for Industrial Motor Safety Monitoring

Omron · Motors & Motion

Description  The Omron SR125SMS4503 is a stop motion sensing unit designed to monitor motor deceleration by detecting residual back electromotive force (back-EMF). It confirms when rotating machinery has reached a safe stop before enabling guard unlocking or machine access. The Omron SR125SMS4503 is widely used in industrial safety systems to improve personnel protection and machine control.     Technical Specifications  Condition New/Never Used Surplus Brand Omron Category Safety Equipment Part Number SR125SMS4503 Subcategory Stop Motion Sensing Unit Device Type Safety Monitoring Relay Supply Voltage 24 VDC Power Consumption ≤ 3.0 W Detection Method Back-EMF sensing Detection Threshold Adjustable from 0.01 V to 0.10 V Safety Outputs 1 N/O and 1 N/C relay contacts Auxiliary Outputs 2 solid-state signaling outputs Mounting 35 mm DIN Rail Protection Rating IP40 housing, IP20 terminals Operating Temperature -10°C to +55°C (14°F to 131°F) Approvals UL, CSA, TÜV, CE, EN ISO 13849-1, EN62061 Weight 0.45 kg (0.99 lb)       Information About SR125SMS4503 The Omron SR125SMS4503 is a compact stop motion sensing unit designed to detect when motors have completely stopped by monitoring residual voltage (back-EMF). As part of Omron’s safety relay lineup, this unit provides secure monitoring of motor deceleration for safe interlocking of guards and brakes. Featuring adjustable sensitivity and solid-state auxiliary outputs, the SR125SMS4503 ensures precise and reliable zero-speed detection. Although now discontinued, it remains widely used in legacy motor control safety applications. Key Features: Back-EMF Detection: Monitors motor winding voltage to confirm stop condition before releasing safety interlocks. Relay and Solid-State Outputs: Provides one N/O and one N/C relay output plus two auxiliary semiconductor outputs for signaling zero-speed status. Adjustable Threshold: Detection voltage threshold adjustable from 0.01 V to 0.10 V for tuning to various motor types. DIN-Rail Mountable: Compact design for easy integration into industrial control cabinets. 24 VDC Supply Voltage: Low power consumption (150 mA) simplifies integration into safety circuits. IP40 Housing / IP20 Terminals: Designed for installation within protected electrical enclosures. High Reliability and Safety Compliance: Certified to EN ISO 13849-1, UL, and TÜV standards for safety relay applications. Diagnostic LEDs: Visual indication of operating status and error conditions. Discontinued Model: Available through surplus and aftermarket channels for supporting legacy equipment. The Omron SR125SMS4503 provides dependable, zero-speed detection for machine safety systems, helping prevent access to hazardous areas until motor motion ceases. Its reliable back-EMF monitoring, flexible outputs, and safety certifications make it a trusted solution for ensuring operator protection in legacy motor-driven applications.

Brand: Omron · Category: Motors & Motion

Key features

• Back-EMF Detection: Monitors motor winding voltage to confirm stop condition before releasing safety interlocks.
• Relay and Solid-State Outputs: Provides one N/O and one N/C relay output plus two auxiliary semiconductor outputs for signaling zero-speed status.
• Adjustable Threshold: Detection voltage threshold adjustable from 0.01 V to 0.10 V for tuning to various motor types.
• DIN-Rail Mountable: Compact design for easy integration into industrial control cabinets.
• 24 VDC Supply Voltage: Low power consumption (150 mA) simplifies integration into safety circuits.
• IP40 Housing / IP20 Terminals: Designed for installation within protected electrical enclosures.
• High Reliability and Safety Compliance: Certified to EN ISO 13849-1, UL, and TÜV standards for safety relay applications.
• Diagnostic LEDs: Visual indication of operating status and error conditions.
• Discontinued Model: Available through surplus and aftermarket channels for supporting legacy equipment.

Specifications

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