Description
Key Technical Specifications
| Parameter | Value |
| Nominal Input Voltage | 24 V DC |
| Operational Input Range | 18 to 30 V DC |
| Regulated Output Voltage | 5 V DC (±1% tolerance tracking) |
| Maximum Continuous Current | 40 A |
| Rated Load Power Capacity | 200 W continuous output |
| Primary Internal Fuse Protection | 20 A fast-acting cylindrical fuse (Part: 5672827-20) |
| Enclosure Dimensions | 72 mm (H) x 162 mm (W) x 238.5 mm (D) |
| Module Net Weight | 2.35 kg |
| Rack System Location | Installs natively within DSRF 197K01 or standard AC410/AC460 subracks |
| RoHS Compliance Status | Exempt via Directive 2011/65/EU Article 2(4) exclusions |
Product Introduction
The ABB DSSR122 (48990001-NK) is a high-capacity, ruggedized DC-to-DC power supply and regulator module engineered for the Advant Master Process Control System. It accepts a raw 24 V DC facility distribution input and converts it into a highly stabilized, precision-regulated 5 V DC rail delivering up to 40 A of continuous current. This 5 V rail serves as the backbone power link, energizing central processing units, communication bus controllers, and dense S100 I/O rack modules sitting within an AC410, AC450, or Safeguard system chassis enclosure.
Plant managers specify the DSSR122 power module to secure the continuous operational life of critical manufacturing, marine, and power distribution systems that rely on the Advant OCS topology. Designed to absorb severe voltage ripples and thermal loads without dropping its regulation envelope, the unit prevents data corruption and processor dropouts on backplane buses. The module handles high inrush currents natively and contains dedicated physical fuse pathways to prevent a downstream component short from taking out your entire facility loop power grid.
- DSSR122 4899001-NK
- DSSR122 4899001-NK
Technical Pitfall & Survival Guide
- The High-Current Cold Connection Hazard
❗ Risk: Reusing worn, corroded, or loose backplane connector clips when sliding the replacement module into the subrack frame. At a 40 A current draw, even a tiny 0.05-ohm terminal resistance contact creates localized thermal dissipation over 80 watts, which will melt the rear terminal block within hours.
- Avoidance: Inspect the socket fingers in the card cage using a bright flashlight before insertion. Clean away oxidization with a dedicated contact chemical, and check that the tension clips have not lost their clamping spring force. If the socket shows signs of prior overheating or discoloration, the backplane frame itself must be repaired or replaced.
- The “Magic Smoke” Input Reverse Polarity Trap
❗ Risk: Relying on terminal color codes or wire orientation from old field modifications when reconnecting the main 24 V DC feed. Reversing the input connections will blow the internal 20 A barrier fuse instantly and can cause avalanche diode breakdown across the regulation logic layout if powered repeatedly.
- Avoidance: Never wire from memory. Use a digital multimeter to verify the absolute polarity of the incoming 24 V DC lines before plugging the feed connector into the DSSR122. I watched a technician on a turnaround shift hook up an incoming power feed without testing polarity; the internal 20 A fuse popped instantly, and because they bypassed testing, it delayed the startup sequence by an entire shift. Verify before you seat the connector.
- Sharing Ventilation Pathways Under Full Load
❗ Risk: Blocking the natural convection airflow vents by mounting heat-generating components directly beneath or beside the supply chassis. At full 40 A capacity, the unit depends heavily on clear vertical airflow; trapping heat cooks the internal electrolytic capacitors, leading to an unexpected output voltage drop.
- Avoidance: Maintain the mandatory clear boundary envelope specified around the subrack assembly. Never stack wire ducts or external components flush against the ventilation patterns of the card housing frame.
Troubleshooting Quick Reference
| Symptom | Possible Cause | Relevance to this Part | Quick Check Method | Recommendation |
| 5 V DC bus reads dead; input power is active | Internal 20 A fast-acting fuse has cleared due to an overcurrent event or reverse polarity. | ✅ High | Power down the system. Pull the module and measure continuity across internal fuse position 5672827-20. | If the fuse is open, locate and clear any short circuits across the S100 backplane cards before putting in a replacement 20 A fuse. |
| 5 V DC output sits low (e.g., 4.2 V DC) under load | Input supply voltage sag or internal capacitor aging under full load conditions. | ✅ High | Measure the incoming voltage directly at the unit terminals under load. Verify it stays above 18 V DC. | If the input supply is a clean 24 V DC but the output sags significantly below 5 V DC at high current, internal components are degraded. Swap out the power supply. |
| Processor cards boot, then throw intermittent reset errors | Excessive voltage ripple or high-frequency noise bleeding through the 5 V DC power link. | ✅ High | Set your multimeter or portable oscilloscope to AC coupling mode. Probe the 5 V DC output terminals for ripples over 50 mV. | High AC ripple confirms the internal filter circuits have failed. Replace the DSSR122 module to protect your processor cards. |
| Upstream 24 V DC facility breaker trips instantly | Direct short circuit across the input conditioning stages of the module. | 🟡 Medium | Disconnect the input plug from the . Measure resistance directly across the L+ and M input pins. | If the reading shows less than 2 ohms, the input surge varistor or clamping network has failed shorted. The unit must be replaced. |
Frequently Asked Questions (FAQ)
Does this power supply module include the required 20 A replacement fuse inside the box?
Yes, every New Surplus unit comes equipped with a fresh, factory-verified 20 A main protection fuse (part number 5672827-20) installed directly on the circuit rail. We also perform full-load compliance checks on every item before packaging to guarantee that the fuse and surrounding circuitry handle high inrush environments without clearing early.
Can I adjust the output voltage slightly higher, for instance to 5.2 V DC, to compensate for long cable runs?
No, the 5 V DC output on the is fixed and precision-regulated at the factory to maintain strict tracking tolerances within ±1%. There are no user-accessible trim potentiometers on the faceplate. This design choice prevents field technicians from accidentally over-voltaging sensitive Advant Master CPU components and communication cards.
Why does the official documentation list this item as RoHS exempt under Article 2(4)?
Because the is a dedicated utility component manufactured exclusively as a direct spare part for legacy industrial infrastructure (specifically the Advant Master Process Control System), it qualifies for specialized industrial exemptions regarding specific lead-solder compositions. This ensures full hardware compatibility with older, lead-alloy backplane systems.
Is it safe to run two units directly in parallel to supply a massive 80 A load rail?
You cannot wire standard standalone modules directly in parallel for load-sharing without using an external diode auctioneering and balancing network assembly (such as a dedicated subrack configuration setup). Connecting the outputs directly together can cause unequal loading, where one module saturates to 100% capacity and overheats while the other remains idle.
What is the primary difference between the 48990001-NK part number and older revisions?
The 48990001-NK designation identifies the latest factory hardware iteration for the series. It features updated internal components that deliver improved thermal handling, tighter voltage regulation profiles, and higher noise rejection margins compared to older field versions, while maintaining identical form-factor fitment.
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