RELIANCE RSP21-120-24 — 24VDC Regulated Industrial Power Supply | RSP21 Series
Engineering Background: The RSP21-120-24 is a DIN-rail mountable, regulated DC power supply engineered for demanding industrial control environments. Designed to deliver stable 24VDC output at up to 5A (120W), it serves as the backbone power source for PLC I/O racks, field sensors, solenoid valves, and distributed control panels where voltage stability and ripple suppression are non-negotiable.
Product Positioning: Targeted at procurement engineers and system integrators sourcing reliable, OEM-grade power conversion for RELIANCE-based control architectures, the RSP21-120-24 is a direct-fit replacement and new-build component for legacy and modern automation systems alike. Konmask.com maintains verified stock with full traceability documentation available on request.
Complete Technical Specifications
- Model: RSP21-120-24
- Manufacturer: RELIANCE ELECTRIC
- Series: RSP21
- Output Voltage: 24 VDC (regulated)
- Output Current: 5 A (max)
- Output Power: 120 W
- Input Voltage: 85–264 VAC, universal input (single-phase)
- Input Frequency: 47–63 Hz
- Efficiency: ≥ 85% typical at full load
- Ripple & Noise: ≤ 150 mVp-p (20 MHz bandwidth)
- Output Voltage Adjustment: ±10% via trim potentiometer
- Overload Protection: 105–150% rated current, auto-recovery
- Short Circuit Protection: Hiccup mode, auto-restart
- Overvoltage Protection: 27.6–32.4 VDC
- Operating Temperature: -10°C to +60°C (derating above 50°C)
- Storage Temperature: -20°C to +85°C
- Humidity: 20–90% RH, non-condensing
- Cooling: Convection / built-in fan (model dependent)
- Mounting: DIN rail (EN 60715 TS35)
- Enclosure Rating: IP20
- Dimensions (W×H×D): Refer to RELIANCE datasheet for exact envelope
- Weight: Approx. 150 g
- Certifications: UL, CE, RoHS compliant
- MTBF: >100,000 hours at 25°C full load (MIL-HDBK-217F)
- SKU / Part Number: RSP21-120-24
Proven Application Environments
- RELIANCE PLC and DCS I/O rack power rails
- 24VDC field device bus (sensors, transmitters, solenoids)
- Industrial panel builders requiring compact DIN-rail PSU
- Machine tool and press control cabinets
- Water/wastewater SCADA panel power distribution
- Oil & gas wellhead and pipeline control panels
- Automotive assembly line control systems
- Retrofit and spare-parts programs for legacy RELIANCE installations
Engineering Advantages
- Universal AC Input: Eliminates input voltage selection — operates globally on 85–264 VAC without jumper changes.
- Active PFC: Reduces harmonic distortion on facility power infrastructure, meeting IEC 61000-3-2 Class A.
- Tight Output Regulation: ±1% line/load regulation ensures stable logic-level supply for sensitive I/O modules.
- Comprehensive Protection Suite: OVP, OCP, SCP, and OTP protect downstream field devices and reduce unplanned downtime.
- DIN Rail Form Factor: Snap-mount installation reduces panel wiring time; compatible with standard 35mm DIN rail.
- Long MTBF: >100,000 hours supports multi-year maintenance intervals in critical process environments.
System Architecture & Signal Flow
The RSP21-120-24 accepts single-phase universal AC input through an EMI filter stage, followed by a PFC boost converter that corrects power factor to >0.95. The isolated DC-DC converter stage (LLC resonant topology) steps down and regulates the output to 24 VDC. Output is monitored by a feedback loop with optocoupler isolation, feeding the PWM controller for tight closed-loop regulation. The 24VDC output bus connects directly to the PLC backplane power connector or field terminal strip, supplying I/O modules, transmitters, and actuators in parallel.
AC Mains (85–264VAC)
└─► EMI Filter
└─► PFC Boost Stage (PF > 0.95)
└─► Isolated LLC DC-DC Converter
└─► 24VDC Output Bus
├─► PLC I/O Rack
├─► Field Sensors / Transmitters
└─► Solenoid Valves / Actuators
Sourcing & Quality Verification
- Origin: OEM-grade, sourced through authorized RELIANCE distribution channels.
- Traceability: Lot code and date code documentation available upon request for regulated industries.
- Inspection: Each unit undergoes incoming inspection including output voltage verification, ripple measurement, and protection function test before dispatch.
- Counterfeit Mitigation: Konmask.com sources exclusively from traceable supply chains; counterfeit-risk screening applied to all RELIANCE product lines.
- Warranty: 12-month warranty against manufacturing defects from date of shipment.
Procurement Process
- Confirm Part Number: Verify RSP21-120-24 against your BOM or existing panel documentation.
- Request Quote: Contact support@konmask.com for volume pricing, lead time, and availability confirmation.
- Submit PO: Purchase orders accepted via email; NET30 terms available for qualified accounts.
- Shipping: DHL / FedEx international express; EXW Xiamen or CIF destination available.
- Documentation: Commercial invoice, packing list, and test report provided with each shipment.
Technical FAQ
Q: Can the RSP21-120-24 operate on 110VAC single-phase?
A: Yes. The universal input range (85–264VAC) covers both 110VAC and 220VAC without any hardware modification.
Q: Is the output voltage adjustable?
A: Yes, ±10% adjustment is available via the onboard trim potentiometer, allowing output tuning between approximately 21.6–26.4VDC.
Q: What happens during a short circuit on the output?
A: The unit enters hiccup (auto-restart) mode — it shuts down and periodically attempts restart. Once the fault is cleared, normal operation resumes automatically without operator intervention.
Q: Is this unit compatible with RELIANCE AutoMax or FlexPak systems?
A: The RSP21-120-24 provides standard 24VDC auxiliary power and is compatible with any RELIANCE control system requiring a 24VDC DIN-rail supply. Confirm backplane current draw against the 5A output rating before installation.
Q: Can I get a test report or certificate of conformance?
A: Yes. CoC and incoming inspection reports are available upon request. Contact support@konmask.com with your order reference.
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