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A step-by-step sizing, selection, and installation guide focused on Leyu Power’s MDR, NDR, and LPV DIN-rail product families. Follow along, and you’ll finish with a spec-checked bill of materials ready for your PLC cabinet. No third-party datasheets or downloads are required.
Industrial automation keeps surging: Analysts peg the global DIN-rail PSU market at ≈ US $2.5 billion by 2030, climbing 6 % CAGR on the back of Industry 4.0 retrofits and smart-factory builds. These compact AC/DC bricks snap onto a standard metal rail, feed everything from PLC CPUs to IIoT edge gateways, and—with the right headroom and derating—run ten years or more without a fan.
DIN EN 60715 defines three common “top-hat” rail profiles:
Rail code | Width × Height |
---|---|
TS35 × 7.5 | 35 mm W × 7.5 mm H |
TS35 × 15 | 35 mm W × 15 mm H |
G-type 15 | 15 mm W × 5.5 mm H |
(35 mm rails cover ~95 % of industrial cabinets.) Allow at least a 7.5 mm air gap on each side of the PSU for cooling and clip clearance.
Parameter | Leyu spec target | Why it matters |
Input range | 88 – 264 VAC | Global mains compatibility |
Output tolerance | ±1 % V<sub>OUT</sub> | Stable PLC & sensor rails |
Ripple/noise | ≤ 100 mV<sub>pp</sub> @ 20 MHz | Prevents analog drift |
Efficiency | ≥ 90 % at full load | Cooler cabinets, lower OpEx |
MTBF | ≥ 300 k h @ 25 °C | Predictable preventive swap-outs |
Series | Power range | Key advantage |
MDR | 15 – 60 W | Ultra-slim housings for dense I/O stacks |
NDR | 75 – 480 W | Wide input + active PFC; “-P” models add current-sharing |
LPV | 35 – 300 W | IP67 epoxy-potted housings for dusty or wet sites |
The golden rule is to sum all steady currents, convert peak/inrush loads, add a future buffer and temperature derating, and then round up to the next nominal wattage.
Device | Qty | Steady I (A) | Inrush × | Duty % | Peak I (A) | Weighted I (A) |
PLC CPU | 1 | 1.2 | 1.0 | 100 | 1.2 | 1.2 |
Servo drive | 2 | 2.0 | 1.8 | 40 | 3.6 | 2.9 |
HMI panel | 1 | 0.6 | 1.0 | 100 | 0.6 | 0.6 |
Totals | – | – | – | – | 5.4 | 4.7 |
Industrial panel guidelines typically reserve 20 % spare capacity for future I/O:
4.7 A × 1.20 ≈ 5.6 A
Leyu NDR units run 100 % up to 50 °C, then derate linearly to 50 % at 70 °C. At 55 °C:
I_derated = 5.6 A × [1 − 0.025 × (55 − 50)] ≈ 4.9 A
Select: NDR-120-24 (24 V, 5 A, 120 W). For redundancy, parallel two NDR-120-24-P supplies.
Protection | Trip point | Recovery |
OVP | 115 – 140 % VOUT | Latch; power-cycle |
OCP | 105 – 140 % IOUT | Hiccup auto-reset |
OTP | +100 °C internal | Auto-restart after cool-down |
Comply with IEC 61010-1 (safety) and EN 55032 Class B (EMC). IEC 60204-1 also recommends documenting spare capacity for risk mitigation.
Mounting orientation: Vertical preferred; horizontal costs ~15 % extra derating.
Clearances: ≥ 25 mm above/below for airflow; keep cable ducts from blocking vents.
DIN-clip torque: 0.6 N·m max—prevents rail distortion.
Conformal coating: Specify in RH > 90 % or salt-fog sites; extends board life.
Wire gauge: AWG 18 (0.82 mm²) for ≤ 5 A; derate one size per 10 °C above 40 °C.
Twist +V and –V conductors to shrink the EMI loop area.
Surge protection: Add Type 2 SPD upstream with high lightning risk (IEC 61643-11).
Negative rail bonding: Bond –V to PE at one point only to avoid ground loops.
Interval | Task |
Startup | Confirm “DC OK” LED steady; adjust trim pot ±1 % of 24 V |
18 months | ESR-test electrolytics; replace if > 2× spec |
3 years | Infrared scan—flag hotspots > 85 °C |
8–10 years | Replace unit during scheduled downtime; recycle per WEEE |
Symptom | Likely cause | Fix |
LED blinking 2 Hz | OCP engaged | Check load for shorts |
Output 0 V, LED off | OTP tripped | Improve airflow, cool the cabinet |
27 V output | OVP latched | Cycle AC mains, verify trim |
Rail type & length (TS35 × 7.5 or TS35 × 15)
Input voltage (single-phase 230 VAC or -phase variant)
Output voltage & continuous current + 20 % buffer
The highest ambient temperature expected
Required safety & EMC marks
Planned future I/O expansion
Tick every box, and a Leyu MDR or NDR unit will slap into it.
Founded in 2005, Leyu Power manufactures ISO 9001-certified switching PSUs, LED drivers, and inverters for 50+ export regions. They are backed by a 2-year warranty and rapid OEM customization.
Question | Answer |
What safety standards must a DIN-rail PSU meet for industrial panels? | At minimum, IEC 61010-1 for electrical safety and EN 55032 for EMC emissions. If shipping to North America, UL 508 listing is common. |
How do I account for temperature when sizing? | Consult the datasheet’s derating curve. Above +50 °C ambient, reduce output current by ~2 % per °C or add forced-air cooling. |
Can Leyu DIN-rail PSUs share current in parallel? | Yes. Models with an “-P” suffix include active current-sharing; set their outputs within ±50 mV before paralleling. |
What is the typical service life? | Leyu specifies MTBF > 300 000 h at 25 °C, translating to 8–10 years of continuous service if the cabinet stays below 50 °C. |
Is field wiring required to be copper only? | IEC 60204-1 recommends copper conductors for control circuits. If aluminium is used, apply antioxidant paste and torque-check annually. |