The Sigmatek SRO 021 is a safety relay output module from the S-DIAS series, engineered for applications requiring high safety standards. It provides two normally open (NO) relay outputs, each capable of handling up to +30 V DC at 6 A. Certified for SIL 3 (EN IEC 62061) and Performance Level e, Category 4 (EN ISO 13849-1/-2), the SRO 021 ensures reliable operation in safety-critical systems.

Key Features:

Model: SRO 021
Brand: Sigmatek
Article Number: 20-893-021
Relay Outputs:
- Number: 2
- Type: Normally Open (NO)
- Voltage Range: Up to +30 V DC
- Maximum Current: 6 A at 55 °C; 4 A at 60 °C
- Response Time: Typically 10 ms
- Fall Time: Typically 3 ms
- Short-Circuit and Overload Protection: External fuse category gG, maximum 6 A
Safety Certifications:
- SIL 3 (EN IEC 62061)
- PL e, Category 4 (EN ISO 13849-1/-2)
- UL 508 (E247993)
Mechanical Features:
- Dimensions (W × H × D): 25 mm × 104.2 mm × 72 mm
- Mounting: DIN rail
- Protection Class: IP20
Environmental Conditions:
- Operating Temperature: 0 °C to +55 °C (up to +60 °C with derating)
- Storage Temperature: -20 °C to +85 °C
- Humidity: 0–95%, non-condensing
- Altitude: 0–2000 m without derating; above 2000 m, derate maximum temperature by 0.5 °C per 100 m
Electrical Requirements:
- Voltage Supply from Safety Bus: +12 V and +24 V
- Current Consumption: Typically 30 mA (+12 V), 90 mA (+24 V)
Applications: Ideal for switching higher power loads or potential-isolated circuits, such as hydraulic valves or emergency stop circuits, in safety-critical industrial automation systems.

Sigmatek - SRO 021 - S-DIAS Safety Relay Output Module, 2x NO, SIL3 / PL e