The MEAN WELL RSD-300C-24 is a fanless railway DC/DC converter with a 24 V output rated at 12.5 A and 300 W. Its C-code input supports continuous operation from 33.6–62.4 VDC and a separate 1-second input range of 28.8–67.2 VDC. The half-encapsulated enclosure provides 4 kVDC input-to-output isolation; available load depends on ambient temperature and the mounting heat-transfer arrangement.
Product Datasheet
Download MEAN WELL RSD-300 Datasheet (PDF)
The RSD-300 section is on PDF pages 42, 43, 44, 45, 46, 47, 48, 49, 50, 51. Refer to the complete mechanical drawings and notes when planning installation.
Model and Output Ratings
| Full model |
RSD-300C-24 |
| Series |
RSD-300 |
| Input version |
C; nominal test input 48 VDC |
| DC output voltage |
24 V |
| Rated output current |
12.5 A |
| Rated output power |
300 W |
| Output current range |
0–12.5 A |
| Output voltage adjustment |
Optional by request; not included in the standard product |
| Maximum ripple and noise |
150 mVp-p |
| Voltage tolerance |
±2.0% |
| Line regulation |
±0.2% |
| Load regulation |
±1.0% |
Use the voltage, current and actual rated power together when selecting the load. The family wattage designation does not replace the rating of this output and input version.
The standard RSD-300 output is not user-adjustable. Request the optional voltage-adjustment configuration from the manufacturer when required.
Input, Timing and Measurement Conditions
| Continuous DC input range |
33.6–62.4 VDC |
| 1-second input range |
28.8–67.2 VDC |
| Typical efficiency |
91.5% |
| Typical DC input current |
7.2 A at 48 VDC |
| Typical inrush current |
45 A at 48 VDC |
| Set-up / rise time |
800 / 50 ms at full load |
| Normal measurement conditions |
48 VDC input, rated load and 25°C ambient |
| Supply interruption classification |
EN 50155:2021, S1 |
The 1-second range is a transient operating condition, not an extension of the continuous input rating. Keep the input within the continuous range for sustained use.
Ripple and noise are measured at 20 MHz bandwidth with a 12-inch twisted pair terminated by parallel 0.1 µF and 47 µF capacitors. Voltage tolerance includes set-up tolerance, line regulation and load regulation.
The catalogue supplies a dedicated RSD-300C-24 hold-up-versus-load curve. Hold-up duration increases as the load is reduced; use that model-specific curve for interruption sizing rather than a single duration for every load.
Protection and Input Safeguards
| Protection functions |
Short circuit, overload, overvoltage, overtemperature and input reverse polarity |
| Overload threshold |
105–135% of rated output power |
| Overload response |
Constant-current limiting; automatic recovery after the fault is removed |
| Overvoltage threshold |
27.6–32.4 V |
| Overvoltage recovery |
Output shutdown; reapply input power to recover |
| Overtemperature recovery |
Output shutdown; automatic recovery after cooling |
| Input reverse polarity |
A MOSFET in series with the negative input opens and prevents output when polarity is reversed |
| Internal input fuse reference |
Conquer UDA-A; time-lag; 16 A, 250 V |
| Inrush limiting |
Start-up resistor bypassed by a MOSFET after start-up |
| Representative 24 V output undervoltage graph |
Turn-off approximately 24.2 VDC; turn-on approximately 25.8 VDC |
Do not operate continuously in the overload region: overheating can reduce service life or damage the converter. The internal fuse reference describes the installed protection component; it is not an external fuse-selection instruction.
When input voltage falls below the undervoltage operating threshold, the controller stops the output. The output resumes automatically after the input rises sufficiently, provided no latched protection remains active.
The representative graph illustrates undervoltage hysteresis below the normal operating band; its plotted thresholds do not extend the permitted continuous input range.
Power Terminals and Indicator
| Input 1 |
DC INPUT V+ |
| Input 2 |
DC INPUT V− |
| Input 3 |
FG |
| Output 1 |
DC OUTPUT −V |
| Output 2 |
DC OUTPUT +V |
| LED status |
Green: normal operation; unlit: no power or a failure |
Connect the DC source and load with the polarities shown and connect FG to the installation protective-earth system. Size conductors and terminations for the current of this model.
Use the mechanical drawing to identify the physical terminal positions. Leave space for terminal access and cable bends; the body dimensions do not include the full installed wiring envelope.
Series Operation and Redundant Supply Connections
| Parallel current sharing |
No built-in parallel circuit; a parallel arrangement does not increase the converter current rating |
| Redundant supply arrangement |
External positive-output isolation diode for each supply, with suitable heat sinking |
| Series output arrangement |
Positive/negative rails or added output voltage; current rating does not increase |
For the illustrated redundant connection, each isolation diode must have a current rating greater than the maximum output current rating of its supply and must be fitted to an appropriate heat sink. Verify the completed external circuit for the intended load.
Parallel supply connections increase leakage current. Confirm installation suitability with the supplier for this application.
For the illustrated voltage-adding series connection, fit external blocking diodes as shown because the units do not contain reverse-blocking diodes. The external diode voltage rating must exceed V1 + V2. Follow the catalogue connection diagram and system insulation requirements.
Cooling, Derating and Environment
| Cooling |
Free-air convection; fanless, half-encapsulated construction |
| Working ambient temperature |
−40 to +70°C, subject to derating and mounting conditions |
| Single-unit ambient load curve |
100% load through 55°C; reduce to 60% at 70°C |
| Additional heat-transfer plate |
360 × 360 × 2 mm iron plate |
| Operation with the specified iron plate |
100% load from −40 to +70°C in the published installation |
| Case-temperature curve |
100% rated current up to 80°C at the marked tc point |
| Working humidity |
5–95% RH, non-condensing |
| Storage temperature / humidity |
−40 to +85°C |
| Temperature coefficient |
±0.03%/°C over 0–55°C |
| Operating altitude |
Up to 5000 m |
| Altitude temperature derating |
Above 2000 m: reduce permitted ambient temperature by 3.5°C per additional 1000 m |
| Vibration |
10–500 Hz, 5 G; 10 minutes per cycle, 60 minutes on each X, Y and Z axis; mounting in accordance with IEC 61373 |
The ambient and case-temperature limits apply together. A permissible case temperature does not by itself waive the ambient-temperature load curve.
To achieve the published full-load 70°C EN 50155 TX arrangement, firmly mount the converter centrally on the specified smooth, even iron plate with good thermal contact. Follow the illustrated orientation and mounting method. The half-encapsulated construction supports the installation orientations shown in the catalogue with the corresponding common derating curve.
Safety, Isolation and EMC
| Catalogue-listed safety approvals |
UL 62368-1; IEC 62368-1; AS/NZS 62368-1; EAC TP TC 004 |
| Additional safety design reference |
BS EN / EN 62368-1 |
| Railway requirements |
BS EN / EN 50155 and IEC 60571; IEC 61373 shock and vibration; BS EN / EN 50121-3-2 EMC; BS EN / EN 45545-2 fire protection |
| Withstand voltage |
Input–output: 4 kVDC; input–FG: 2.5 kVDC; output–FG: 2.5 kVDC |
| Isolation resistance |
100 MΩ between input–output, input–FG and output–FG at 500 VDC, 25°C and 70% RH |
| Conducted emission |
BS EN / EN 55032 (CISPR 32), Class A |
| Radiated emission |
BS EN / EN 55032 (CISPR 32), Class B |
| EMC immunity |
BS EN / EN 61000-4-2/-3/-4/-5/-6/-8; BS EN / EN 55035; light-industry level; EAC TP TC 020 |
| Additional EMC conformity |
EAC TP TC 020 |
Confirm compliance of the completed installation with the applicable EMC and safety requirements. Component test results do not certify the entire vehicle or equipment.
The component EMC tests use a 360 × 360 × 1 mm metal plate. This EMC test plate is distinct from the 360 × 360 × 2 mm iron plate specified for full-load 70°C thermal operation.
Railway Environmental and Fire Test References
The catalogue reports PASS for EN 50155 dry heat (section 13.4.5: 70°C for 6 hours and 85°C for 10 minutes); cyclic damp heat (13.4.8: 25–55°C, 90–100% RH, 48 hours); vibration (13.4.10: 19°C, 65% RH, 10 minutes); shock (13.4.10: 21 ±3°C, 65 ±5% RH, 30 ms ×18); low-temperature storage (13.4.6: −40°C, 16 hours); and salt mist (13.4.13: 35 ±2°C, 96 hours). These are test conditions, not expanded continuous operating limits.
EN 45545-2:2020 fire-test references cover PCB R22 oxygen index (EN ISO 4589-2:2017), smoke density (EN ISO 5659-2:2017) and smoke toxicity (EN 17084:2018); PCB R24 oxygen index; PCB R25 glow-wire (EN 60695-2-11:2014); potting R24 oxygen index; and terminal-block R26 vertical flame (EN 60695-11-10:2013). HL1 and HL2 are marked PASS for every listed item. HL3 is marked PASS for the listed items except PCB R22 smoke density, for which no PASS result is listed.
Mechanical Data and Installation Items
| Catalogue body dimensions, L × W × H |
216 × 96.5 × 40 mm |
| Case reference |
205 |
| Drawing tolerance |
±1 mm |
| Mounting layout |
208 mm longitudinal reference; 4 × R2.1 mounting slots and the marked 2 × R2.1 side features |
| Iron-plate fixing arrangement |
Four M4 screws at the illustrated positions |
| Case-temperature measurement point |
Marked tc in the mechanical drawing |
| Unit mass, catalogue PACKING reference |
1190 g |
| Catalogue packing |
1.19 kg; 12 units / 15.3 kg / 0.97 CUFT |
| Minimum MTBF |
1850.1K hours, Telcordia SR-332 (Bellcore); 130.8K hours, MIL-HDBK-217F at 25°C |
| Nominal switching frequency |
130 kHz |
| Catalogue warranty |
3 years |
| Capacitor specification |
105°C long-life electrolytic capacitors |
| Production test |
100% full-load burn-in test |
The RSD-300 drawing separately shows terminal projections of up to 15 mm at each end. Allow these projections and the required wire-bend clearance beyond the body outline.
The iron plate, fixings and any external connection components must be selected for the installation. Confirm supplied items with the order; the catalogue plate drawing does not establish that a separate plate kit is included.
The mass is the explicit catalogue packing reference per unit, not a measured net mass or the weight of a complete shipping package.
