Leuze - MSI-SR4B-01 - Safety Relay, 3NO + 1NC, 24 V AC/DC, PL e, SIL 3

The Leuze MSI-SR4B-01 (Part No. 547950) is a safety relay designed for applications requiring high safety integrity, such as emergency stop circuits and monitoring of safety switches. It features three normally open (NO) safety contacts and one normally closed (NC) signaling contact, providing reliable performance in safety-critical environments. 

Key Features:

• Model: MSI-SR4B-01

• Part Number: 547950

• Brand: Leuze

• Function: Safety relay for emergency stop and safety switch monitoring

• Supply Voltage: 24 V AC/DC (±20%)

• Power Consumption: Max. 3 W

• Safety Outputs: 3 NO contacts

• Signaling Output: 1 NC contact

• Response Time: 10 ms

• Pickup Delay:

  • Automatic Start: 300 ms

  • Manual Start: 30 ms

• Restart Modes: Selectable automatic or manual restart

• Monitoring Functions: Contactor monitoring (EDM), Cross-circuit monitoring, Start/restart interlock (RES)

• Safety Ratings:

  • Performance Level: PL e (EN ISO 13849-1)

  • Safety Category: 4 (EN ISO 13849-1)

  • SIL: 3 (IEC 61508)

  • SILCL: 3 (IEC/EN 62061)

  • MTTFd: 73 years

  • PFHD: 2.1 × 10⁻⁸ per hour

• Electrical Connection: Screw terminals

• Protection Rating:

  • Terminals: IP20

  • Housing: IP40

• Applications: Ideal for emergency stop circuits, monitoring of mechanical and electronic safety switches, and integration with optoelectronic protective devices in industrial automation systems.