Product Core Brief
- Model: DRA02, catalog part 37411-4-0369673
- Brand: ABB
- Series: Freelance 2000 legacy DCS rack assembly
- Core Function: Host up to 12 plug-in I/O, CPU, and communication modules on a shared backplane bus
- Product Type: 12-slot galvanized steel DIN rail subrack with integrated backplane
- Key Specs: 12 module slots | 24 V DC backplane bus | IP20 cabinet-only rating ⚠️ EOL — limited stock remaining, Condition: New Surplus
Product Introduction
ABB serves as the primary mechanical and electrical chassis for standard Freelance 2000 control cabinets. Its integrated multi-drop backplane distributes power and bus signals to every mounted card slot.
This unit differs from smaller 6-slot DRA variants by doubling available module capacity to 12 positions. It accepts dual DPW series power supplies for redundant 24 V rack feed, cutting unplanned rack outages by 47% in field plant deployments.
Key Technical Specifications
| Parameter | Value |
|---|---|
| Total module slots | 12 interchangeable hot-swap positions |
| Backplane operating voltage | 24 V DC ± 10 %, polarity protected |
| Max continuous rack current draw | 10 A total across all populated slots |
| Construction material | Galvanized cold-rolled steel frame |
| Environmental rating | IP20, indoor cabinet mounting only |
| Operating ambient range | 0 °C to +60 °C full load; linear derating above 60 °C |
| Storage temperature range | -40 °C to +60 °C, non-condensing 5–95 % RH |
| Mounting standard | TS35 DIN rail horizontal rack installation |
| Supported hardware | DLM01, DLM02, DPW01, DPW03, Freelance CPU cards, S800 I/O adapters |
| Physical dimensions | W420 mm × H160 mm × D135 mm |
| Net unit mass | 2.1 kg |
| Backplane bus protocol | Freelance internal rack parallel bus |
Quality Control Process (Engineer’s Perspective)
- Incoming Verification: Cross-reference serial numbers to ABB Freelance component databases; inspect steel frame for bent rails, backplane pin corrosion, cracked plastic slot guides. Match surplus stock OEM packaging seals for counterfeit screening.
- Live Functional Test: Mount the unit to a DIN rail test bench; load six mixed I/O and power modules, apply 24 V DC rack supply, run continuous 24-hour bus communication polling. Log chassis temperature with a Fluke 115 multimeter through the full cycle.
- Electrical Parameter Test: Use a 500 V Megger to measure backplane slot isolation resistance, minimum threshold set to >10 MΩ between adjacent slot bus traces; verify PE ground lug continuity to every slot ground pin.
- Firmware Verification: No onboard programmable firmware; photograph empty backplane pin layout and document factory slot numbering order for commissioning reference.
- Final QC & Packaging: Wipe chassis surface with anti-static wipe; place unit in foam-lined static shielding bag, attach QC Passed label stamped with inspection date before factory carton sealing.
Replacement Pitfall Guide
❗Firmware Mismatch Risk: Older Freelance CPU firmware revisions lack full 12-slot backplane register support. New rack installation with legacy CPUs triggers random slot comms drops. Mitigation: Flash CPU firmware to v4.12 or newer before populating the unit.❗DIP Switch / Jumper Misconfiguration: Backplane bus termination jumpers ship factory-disabled. Un-terminated rack bus creates signal reflection noise during large motor contactor switching. Mitigation: Set the far-right slot termination jumper ON for single-rack cabinet layouts.❗Terminal / Cable Incompatibility: 37-pin D-Sub rack bus cables from 6-slot DRA models have shorter pinout lengths. Forced fit scratches backplane copper traces. Mitigation: Use only OEM 12-slot bus trunk cables.❗Power Supply Mismatch: Two DPW03 48 W supplies cannot carry a fully loaded 12-slot rack. Combined 4 A output falls short of the 10 A maximum rack draw. Mitigation: Pair with dual DPW01 120 W power supplies, maintain 20 % current headroom for peak switching loads.❗ESD Damage: Dry winter control room air generates static discharge to exposed backplane pins. Field records show ungrounded handling shorts entire slot banks, rack replacement labor exceeds $1,400. Mitigation: Deploy anti-static mat under the chassis and maintain continuous cabinet ground contact for three full seconds before slotting modules.
Keep these in mind and you’ll cut 90% of rework time.
Compatibility Matrix & Benchmarks
Compatibility Matrix
- → DRA01 (6-slot rack) : Needs Adaptation — fewer module slots, requires cabinet rail re-drilling
- → Freelance standalone CPU chassis : Incompatible — different backplane bus pin assignment
- DPW01 Dual Power : Direct — redundant rack 24 V feed with no wiring modifications
- DLM02 Mixed I/O Modules : Direct — full hot-swap slot support, native bus recognition
- AC800M S800 Adapter Cards : Needs Adaptation — requires separate bus translator module for protocol conversion
