NI 9481 4-Channel C Series Relay Output Module

The NI 9481 is a 4-channel C Series relay output module engineered for high-voltage and high-current switching in industrial control and automation systems. It integrates directly into NI CompactDAQ and CompactRIO chassis platforms, delivering electromechanical Form A (SPST) relay switching at up to 250 VAC or 60 VDC with 2 A per channel capacity. Each relay operates at 1 cycle per second with 10 ms maximum engage time and 5 ms maximum release time, supported by 20,000,000 mechanical operations and 100,000 electrical operations over its lifetime. The module operates across –40 °C to 70 °C and draws a maximum 580 mW in active mode. Screw terminals accept 12 to 24 AWG copper conductors, while 250 Vrms channel-to-channel isolation ensures safe multi-channel operation. Off-state leakage is limited to 10 μA maximum. The compact design measures 12.1 cm × 8.6 cm × 2.5 cm and qualifies for Class I, Division 2 hazardous locations (Groups A, B, C, D, T4) and Class I, Zone 2 (AEx nC IIC T4). EMC compliance covers EN 61326, CISPR 11, and FCC Part 15B Class A emissions standards.

– Technical Specifications

• Relay Type: Single-Pole Single-Throw (SPST) Form A Electromechanical
• Channels: 4
• Switching Capacity: 30 VDC at 2 A; 60 VDC at 1 A; 250 VAC at 2 A per channel
• Switching Rate: 1 operation per second
• Operate Time: 10 ms maximum
• Release Time: 5 ms maximum
• Relay Bounce: 3 ms
• Off-State Leakage: 10 μA maximum
• Mechanical Life: 20,000,000 operations
• Electrical Life: 100,000 operations
• MTBF: 460,321 hours at 25 °C (Bellcore Issue 2, Method 1, Case 3)
• Channel Isolation: 250 Vrms
• Power Consumption (Active): 580 mW maximum
• Power Consumption (Sleep): 5 mW maximum
• Thermal Dissipation (Active, 70 °C): 1.5 W maximum
• Thermal Dissipation (Sleep, 70 °C): 5 mW maximum

– Key Features

• Screw terminals support 12 to 24 AWG copper wire with 0.5–0.6 N·m torque specification
• Operating and storage temperature range: –40 °C to 70 °C
• Measurement Category II classification
• Channels default to off state upon power-on
• Low thermal footprint: 5.3 oz; 12.1 cm × 8.6 cm × 2.5 cm

– Compatibility & Integration

• Direct installation into NI CompactDAQ and CompactRIO chassis
• Rated for Class I, Division 2 hazardous locations (Groups A, B, C, D, T4) and Class I, Zone 2 (AEx nC IIC T4)
• Suitable for indoor use; outdoor deployment requires IP 54–rated enclosure
• Compliant with EN 61326, EN 55011, AS/NZS CISPR 11, FCC 47 CFR Part 15B, and ICES-001 Class A emissions