ABB DO821 3BSE013250R1 Digital Output Module

Description

ABB DO821 3BSE013250R1 Digital Output Module

Product Overview

The ABB DO821 (Catalog / Part Number: 3BSE013250R1) is an 8-channel relay digital output module designed for ABB’s S800 I/O system. It is widely used in System 800xA, Compact Product Suite, and Symphony Plus distributed control systems (DCS).

Unlike standard transistor modules, the DO821 features Normally Closed (NC) relay contact outputs that are individually galvanically isolated per channel. Operating up to 250 V AC/DC and supporting switching currents up to 3 A per channel, it provides robust interfacing between control logic and heavy-duty field devices.

Technical Specifications

Key Advantages

• Individual Channel Isolation: Every output channel has complete galvanic isolation from other channels and system logic, preventing cross-channel interference and eliminating ground loop risks.
• High Load Switching Capacity: Handles up to 3 A continuous load at 250 V AC/DC, enabling direct switching of contactors, solenoids, interlocks, and alarm devices without external interposing relays.
• Normally Closed (NC) Design: Ideal for fail-safe application loops, safety interlock chains, and emergency shutdown circuits where active opening or break-on-energize control is required.
• Integrated OSP (Output Set Protection): Allows maintenance teams to configure deterministic fallback states (Keep Last Value or Trip to Safe State) for each output in the event of communication loss with the CPU.
• Clear Diagnostics & Hot-Swappability: Front LED indicators provide immediate visual feedback for channel status and internal faults; supports hot-swapping under power when mounted on standard S800 Module Termination Units (MTUs).

Important Usage & Installation Precautions

• Contact Contact Rating Limits: Never exceed the 3 A continuous current rating per channel or 250 V AC/DC voltage limit. For highly inductive loads (such as large solenoid valves or contactor coils), fit external surge suppressors (RC snubbers for AC or flyback diodes for DC) across the field device to extend relay contact life.
• Module Termination Unit (MTU) Selection: Ensure proper MTU selection (e.g., TU811V1 or TU813) rated for 250 V isolation to ensure compliance with electrical safety standards.
• Mechanical Relay Lifespan: Because DO821 uses electromechanical relays, avoid using this module for high-frequency pulse switching (such as PWM control or rapid cycling). Use transistor-based output modules (e.g., DO810) for high-speed switching requirements.
• Power Monitoring Parameter: The relay supply voltage supervision on the internal 24 V DC conversion rail triggers a warning signal if voltage drops. Ensure system parameters in ABB Control Builder are correctly configured to monitor or suppress these diagnostics according to application needs.
• Thermal Management: Operate within the recommended ambient temperature range (0 °C to +55 °C). Maintain adequate vertical clearance around the module rack inside control cabinets for natural convective heat dissipation.

Applications

• Safety Interlock & Shutdown Circuits: Tripping power feeds or closing fail-safe valves in emergency shutdown (ESD) applications using Normally Closed logic.
• Power Distribution & MCC Control: Direct tripping and switching of circuit breakers, motor starters, and contactors in medium and low-voltage switchgear.
• Process Valve & Solenoid Control: Operating motorized valves, air solenoids, and actuators in chemical processing, oil & gas, and water treatment plants.
• Alarm Annunciation & Horn Systems: Actuating plant-wide optical and acoustic warning sirens, beacons, and remote indicator panels.

Shipping Port: Xiamen, China

Payment: Bank of Chicago, Bank of Singapore

Express cooperation: fedex, DHL, UPS and your express account

Service: Professional Sales provides 24 hours /7 days online service

Please make an inquiry for more models：