Product Core Brief
- Model: CMA198
- Brand: ABB
- Series: CMA HR rack DC-DC power supply family for Symphony Plus Harmony racks
- Core Function: Delivers regulated isolated 5 VDC logic power to HR rack CPUs, fieldbus, and analog I/O cards from rack 24 VDC backplane input
- Product Type: Single-width hot-swappable HR rack plug-in power PCB
- Key Specs: 24 VDC wide input | 5 VDC 4 A continuous output | 500 VAC input-output galvanic isolationCondition: New Original (New Surplus) | Factory Sealed; active production spare supported through 2035
Key Technical Specifications
| Parameter | Value |
|---|---|
| Compatible Hardware | Symphony Plus HR/Harmony racks, SPBRC410 CPUs, PDP800, SPASI23 I/O modules; incompatible with AC800M / UNITROL subracks |
| Input Voltage Range | 18 VDC to 32 VDC nominal 24 VDC rack feed |
| Regulated Output | 5 VDC ±1% tolerance, max 4 A continuous (20 W total power) |
| Galvanic Isolation | 500 VAC continuous withstand between input and logic output ground |
| Cooling Design | Passive natural convection, no internal cooling fan |
| Built-In Protections | Reverse polarity lockout, overvoltage cutoff, foldback overcurrent, auto-recovery short-circuit protection |
| Backplane Power Draw | 7.2 W full rated load |
| Hot Swap Rating | HR rack certified hot-swap; parallel units maintain rack power during single card replacement |
| Operating Ambient Temp | -10 °C to +50 °C full 4 A output; linear thermal derate above 50 °C |
| Storage Temperature | -40 °C to +85 °C, 5–95% RH non-condensing |
| Mechanical Size | 28 mm W × 185 mm H × 128 mm D single HR slot; 0.52 kg weight |
| Compliance | CE, UL, RoHS, IEC 61010 safety standard, IEC 61000-6-2 Class A EMC |
Product Introduction
This unit serves as a rack-mounted isolated DC-DC converter dedicated to Symphony HR DCS cabinets. It converts unregulated 24 VDC rack auxiliary power into clean, noise-suppressed 5 V logic rail power for all rack control and measurement hardware.Its 500 V isolation barrier blocks ground-loop interference common in turbine hall environments, eliminating spurious analog measurement drift and fieldbus communication timeouts that occur with unisolated legacy power variants. Parallel stacking scales total available 5 V capacity for dense racks filled with multiple CPUs and I/O modules.
QA & Testing SOP (Transparency Building)
- Incoming Inspection: Cross serial numbers against ABB Symphony OEM trace databases. Inspect gold HR backplane edge connector for oxidation, PCB solder joints for microcracks, and front power/fault LED for dead segments. Verify unbroken factory anti-static seal for surplus inventory.
- Live Testing: Seat the PCB in a populated HR test rack loaded with SPBRC410 CPU and full resistive 4 A load bank. Run 24-hour continuous full-load cycling. Simulate output short-circuit events to validate auto-recovery protection. Track 24 V backplane stability with a Fluke 115 precision multimeter for the full test window.
- Electrical Testing: Execute 500 VAC megger insulation test between DC input circuits and chassis PE ground; pass threshold set at >10 MΩ. Validate reverse 24 V polarity protection triggers without damaging internal switching semiconductors.
- Firmware/Config Backup: Record factory calibrated 5 V output offset and overcurrent trip thresholds. Document rack parallel load balancing templates for plant cabinet power sizing reference.
- Final QC & Packaging: Wipe gold backplane connector pins to remove storage oxidation. Encase the PCB in anti-static foam inside shock-resistant export cartons. Apply physical QC Passed labels listing serial number and completed test metrics. Test logs and bench oscilloscope data available for pre-shipment review upon request.
Installation Pitfalls & Guide (Engineer to Engineer)
❗Firmware Mismatch Risk: Power module firmware does not interact with CPU firmware, but mixing old CMA110 variants with the device creates uneven load sharing across parallel supplies.Risk Outcome: Uneven thermal loading, early derating, and intermittent 5 V voltage dips during high CPU scan cycles.Prevention Step: Match all rack power supplies to identical model lines; photograph existing power hardware before ordering replacements.
❗DIP/Jumper Error Risk: This hardware has no field-adjustable jumpers, but misidentifying slot assignments leads to unbalanced rack power distribution.Risk Outcome: Single supply carries 100% rack load, triggering thermal cutoffs.Prevention Step: Map each CMA slot to its CPU/I/O load group in S+ Composer documentation before rack assembly.
❗Wiring Incompatibility Risk: UNITROL/ACS6000 subrack backplane pinouts do not carry HR rack 24 V power rails.Risk Outcome: Zero 5 V logic power delivery if installed on non-HR platforms.Prevention Step: Restrict deployment exclusively to Symphony HR Harmony racks only.
❗Power Draw Miscalculation Risk: Six high-load I/O cards and two SPBRC410 CPUs exceed the device’s 4 A single-unit rating.Risk Outcome: Persistent overcurrent foldback, unstable analog channel readings.Prevention Step: Maintain minimum 20% power overhead per supply; split dense I/O loads across multiple parallel power PCBs.
❗ESD Dangers: Static discharge from dry turbine hall air damages high-frequency DC-DC switching chips on the PCB. A single ungrounded handling incident can destroy $1,800 worth of control hardware.Risk Outcome: Permanent output ripple drift with no visible exterior damage.Prevention Step: Touch bare cabinet ground metal for three full seconds before handling backplane edge connectors.
4-Step Replacement Guide
- Pre-install: Confirm rack holds at least two parallel power supplies to avoid full rack power loss during swap. Capture photos of the backplane connector alignment before removal.
- Removal: Locate the release latch on the HR card slot, pull straight outward without twisting the PCB to avoid bending gold edge pins.
- Install: Align the new unit’s edge connector with the rack backplane, push fully seated until the latch clicks into locked position.
- Power-on Test: Monitor front power LED steady green; cycle all rack CPUs and I/O to confirm no analog measurement noise or bus communication errors.
FAQ
Q: I maintain an aging Harmony HR boiler rack with failing legacy CMA110 power supplies paired with SPBRC410 controllers. Can this unit serve as a direct drop-in replacement without rack rewiring?A: Yes. The PCB shares identical HR slot mechanical form factor, backplane power pin mapping, and terminal rail layout as older CMA110 hardware. No cabinet wiring modifications are required, and parallel load sharing functions without software reconfiguration.
Q: What lead times apply for stocked hardware versus pre-calibrated custom variants?A: Standard in-stock assemblies ship within 3–5 business days via global air freight. Custom factory pre-calibrated output offset variants carry a 12–16 week OEM lead time and are not stocked as surplus inventory.
Q: Does the 12-month warranty cover damage from overloaded rack loads or ESD mishandling?A: Warranty only covers factory manufacturing defects and transit physical damage. Sustained overcurrent operation, ungrounded ESD handling, and installation on incompatible non-HR rack backplanes fall outside covered failure modes. Paid remote rack power load sizing support is available to resolve configuration errors post-install.
Q: Can multiple copies of the device run in parallel to expand total rack 5 V logic power capacity?A: Yes. The internal load-sharing circuit automatically distributes current evenly across all parallel units. For racks with more than four high-power I/O modules, add a second supply to maintain the 20% overhead margin.
Q: Is this power PCB rated for Class 1 Div 2 hazardous cabinet installation inside refinery MCC rooms?A: No. The open HR slot PCB design lacks intrinsic safety ratings for classified explosive atmosphere locations. ABB manufactures separate IS-certified power hardware lines for hazardous area cabinet deployments.
Q: Can I install this power supply into a UNITROL 6000 generator excitation subrack to power PPC902AE101 processors?A: No. UNITROL AC800PEC subracks use proprietary 24 V power distribution pinouts incompatible with HR rack backplane design. Power conversion for excitation CPUs requires dedicated UNITROL-series power modules instead.
Q: What QA documentation ships with each unit for plant maintenance record retention?A: Every PCB includes a physical QC Passed label stamped with serial number and completed test checklist metrics. Digital copies of 24-hour full-load cycling logs, 500 V insulation megger reports, and short-circuit auto-recovery validation data can be emailed prior to shipment upon buyer request.
