ABB DO802
ABB DO802 - Image 2

ABB DO802

Product Brief:​ The DO802 belongs to ABB S800L (larger-form-factor) I/O family. It provides eight independently isolated electromechanical relay contacts (Form A / NO) for switching AC or DC loads up to 250 V AC / 110 V DC at 2 A. It is used when the load voltage/current exceeds solid-state capability or when isolation between outputs is required. Relay coil is driven from the 24 V DC ModuleBus supply with supervision.

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Category: SKU: ABB DO802

Description

ABB DO802

  • Technical Specifications:
    • Output Type: Electromechanical relay, SPST-NO (Form A)
    • Channels: 8, each channel fully isolated from others and from ModuleBus
    • Rated Switching Voltage: Max 250 V AC, max 110 V DC (some versions 125 V DC — verify label)
    • Rated Switching Current: 2 A resistive @ 250 V AC / 110 V DC; cos φ > 0.4 for AC
    • Minimum Applicable Load: 10 mA / 5 V DC (contact wetting requirement)
    • Contact Material: Silver alloy (AgCdO or AgSnO₂)
    • Operate / Release Time: Typ. 10 ms / 5 ms
    • Mechanical Life: >10 million operations (no load); electrical life ≈100,000 ops @ rated resistive
    • Isolation Voltage: 2000 V AC channel-to-channel and channel-to-coil
    • Relay Coil Supply Supervision: Monitors 24 V on ModuleBus; warning if lost
    • Power Dissipation: Typ. 2.2 W (all relays energized)
    • ModuleBus Current: +5 V typ. 70 mA; +24 V typ. 80 mA
    • Max Field Cable Length: 600 m
    • Operating Temp.: 0 °C to +55 °C
    • Dimensions: 86.1 mm (W) × 110 mm (H) × 58.5 mm (D); weight ≈0.24 kg
    • MTU: Dedicated S800L terminal unit
    • Certifications: CE, UL/cUL, ATEX Zone 2, marine
  • Functional Features:
    • Full isolation between each relay channel — allows mixing AC/DC loads safely
    • Relay coil voltage supervision with diagnostic reporting
    • Per-channel status LED (yellow = relay energized)
    • Varistor (MOV) across coil for spike suppression
    • Suitable for switching lamps, solenoid valves (AC), motor starter coils, alarm horns
  • Application Scenarios:
    • Switching 230 V AC alarm sirens / beacons in plant annunciator systems
    • Controlling 110 V DC / 230 V AC motor starter coils (interposing relay function)
    • Mixed-voltage loads in one I/O station (one channel 24 V DC, another 230 V AC — fully isolated)
    • Legacy equipment interfacing where dry-contact closure is required
  • Material & Structure:
    • Housing: Flame-retardant polycarbonate (S800L wider format)
    • Relays: Plug-in style with silver alloy contacts; replaceable in some S800L designs (check version)
    • Terminals: Screw type on S800L TU
  • Working Principle:

    The module receives a ‘1’ in the output image for a given channel; an opto-isolator triggers the relay-driver transistor which energizes the relay coil from the 24 V ModuleBus supply. The NO contact closes, connecting the field load to its supply. Loss of 24 V ModuleBus or communication error is detected and reported; the module can be configured to leave relays in last state or de-energize on comm loss.

  • Installation Requirements:
    • Mount in designated S800L terminal unit on 35 mm DIN rail
    • Wire load between COM and NO terminal of each channel; observe voltage/current ratings
    • For inductive AC loads (contactors, relays), fit external RC snubber or use contact-protected version to extend contact life
    • Verify relay coil supply (24 V ModuleBus) is present before expecting output operation
  • Precautions:
    • Do NOT exceed 2 A resistive or specified VA rating — contact welding may occur
    • Minimum load: very low current (<10 mA) may cause contact oxidation (“dry circuit” issue) — for very small signals use solid-state DO
    • Relay click is audible — consider in quiet environments
    • Replace relay at end of electrical life; verify correct replacement part number matches voltage/current rating
    • Do NOT switch 230 V AC and 110 V DC on same channel simultaneously — follow nameplate limits

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