Dernière mise à jour: October 3, 2026
Quick réponse: A constant voltage power supply aims to maintain its specified DC voltage while a compatible load draws current within the supply’s operating limits. For industrial OEM controls, the acceptance question is not just whether the label says 24 V: check voltage at the load, simultaneous current demand, load-step recovery, protection behaviour and temperature in the intended enclosure. WEHO NDR-120-24 is a source-verified 24 V, 5 A, 120 W DIN-rail example; those ratings alone do not prove machine compatibility or a particular transient response.
An industrial constant voltage power supply is useful when compatible controllers, sensors and other DC devices need a shared nominal voltage. Their current demand can change with machine state. The supply attempts to regulate voltage, but cables, connectors, dynamic loads and protection limits affect what each device actually receives.
This guide focuses on OEM acceptance planning for a 24 V auxiliary-control bus. It does not address constant-voltage LED-strip sizing or compare regulated and unregulated architectures. Separate actuator or machine-drive power from the electronic control circuit before choosing the supply.
Start with the control bus and the worst machine state
Create a load register listing each device’s permitted voltage range, normal current, startup or pulse demand, duty cycle and fault implications. Use the device manufacturer’s data and measure uncertain demands. “Typical current” is not a dependable maximum for an entire machine state.
Map simultaneous operation rather than simply averaging a production cycle. A controller, interface and several sensors may remain active while another peripheral starts. Determine which demands overlap, then compare that state with the supply’s current capability under the intended temperature and installation conditions. Do not count motor or cutting-drive power as a low-voltage control load without evidence that it belongs on that bus.
For an arithmetic example only, a hypothetical 3.2 A steady state at 24 V corresponds to 76.8 W; a 4.4 A overlapping state corresponds to 105.6 W. Both sit below the NDR-120-24 nameplate’s 5 A and 120 W, but this is not a release decision. Unknown startup peaks, permissible voltage dips, cabinet temperature and branch protection still need review. There is no universal headroom percentage that replaces those checks.
Identify the exact supply and the controlled revision
Le WEHO NDR-120 product page identifies NDR-120-24 at 24 V and 5 A. The current specification’s mechanical envelope is 40 mm width × 125.2 mm height × 113.5 mm depth. Its rear mounting engages a 35 mm DIN rail; the blue front label and accessible terminals face outward. It is a fanless metal unit, not a generic plastic DIN enclosure.
The exact source photo prints nominal input “100-240VAC 2.6A” and “50/60Hz.” The current NDR-120 specification separately lists an operating input range of 85–264 VAC and 47–63 Hz. Keep these document roles distinct and obtain confirmation for the ordered revision before electrical release. Conflicting public-page input or enclosure wording is not used to extend the product’s operating limits here.
The source has four upper DC terminals ordered −V, −V, +V, +V, and three lower input terminals ordered protective earth, N, L. Repeated output terminals do not create additional independent 5 A outputs: assess the connected total against the model rating. Follow the controlled drawing, terminal instructions and project protection design, rather than deriving a wiring scheme from an illustration.
Measure the load voltage, not only the supply terminals
Define two measurement points: voltage at the supply output and voltage at the most demanding or electrically distant device. Record the machine state and current at the same time. Connector and cable resistance can cause the two voltages to differ even when the supply terminals appear stable.
For a simplified hypothetical calculation, 4 A through a combined outgoing-and-return path resistance of 0.10 Ω gives a 0.40 V resistive drop. A 24.00 V source would then leave approximately 23.60 V at that load, before considering other effects. This is a design illustration, not a measurement of WEHO hardware. Determine the real path resistance, connection quality, cable temperature and load tolerance for the project.
Do not raise the adjustment setting solely to compensate for one distant branch. Check every connected device’s permitted maximum voltage, light-load condition and shortest branch first. The visible +V ADJ control does not establish remote sensing or automatic cable-drop compensation; neither feature is claimed in this guide.
The first application image shows a standalone carton-label-printing evaluation fixture beside a desktop printer. It represents space and access planning for a possible auxiliary-control supply, not proof that the supply operates the printer. The NDR-120-24 terminal apertures are empty and its DC OK indicator is dark. The background printer provides application context only; its Ready screen is not a supply measurement, verified connection or acceptance result. Determine the printer interface and actual electrical requirements independently.
Agree the load-step acceptance criteria before testing
A steady voltage reading does not describe a rapid change in demand. Write a test plan identifying the step’s starting and ending currents, rise behaviour, repetition, supply input condition, cable arrangement, measurement points and operating temperature. Select these conditions from the actual device demands, not from an attractive nominal wattage.
Have the responsible engineer define the load’s acceptable minimum and maximum voltage, allowed excursion duration and recovery requirement. Then use suitable instrumentation and safe test procedures to record both supply-terminal and remote-load voltage during the transition. Distinguish steady-state regulation, ripple, startup and load-step response; one observation cannot substitute for all four.
This article supplies no verified load-step waveform, recovery time or machine test result for NDR-120-24. Ask WEHO for applicable controlled dynamic-performance information and validate the chosen sample in the intended system. If evidence is missing or a device resets, the result is an open engineering action—not an automatic pass because average current is below 5 A.
The second illustration places an isolated fitting fixture beside a textile cutting table during retrofit preparation. Auxiliary controller electronics are separate from the cutting drive. This different mechanical context does not establish load compatibility, immunity to workshop disturbances or completed commissioning. Verify the real cabinet environment and subsystem boundary before installing the component.
Close the thermal, protection and procurement file
Confirm the actual enclosure temperature, airflow, orientation, spacing and cable access against the ordered revision’s installation requirements. A fanless supply still needs a valid thermal path and cannot be qualified by ambient room temperature alone. Keep ventilation openings clear and add necessary clearances outside the documented product envelope.
Review branch faults and protective devices with the machine designer. A supply’s protection feature is not a blanket promise of selective protection for every branch. Plan any fault or recovery test safely, document the required equipment behaviour and investigate unexpected controller resets or repeated recovery cycles.
For an RFQ, provide the voltage tolerance, verified concurrent demand, pulse profile, cable layout, enclosure conditions and release criteria. Request the exact full-model specification, mechanical drawing and applicable installation information. Retain the confirmed revision, sample measurements, deviations and reviewer decision together; an AI image is not commissioning evidence.
Points clés à retenir
- Treat 24 V regulation as a bounded capability, not an unlimited-current guarantee.
- Check simultaneous current and voltage at the actual load connection.
- Define load-step limits from device requirements before evaluating a sample.
- Keep photo label, operating-range specification and ordered revision distinct.
- Release only after mechanical, thermal and protection questions are resolved.
Conclusion
Choosing a constant voltage power supply for industrial controls is an evidence-led acceptance task. NDR-120-24 provides a documented 24 V, 5 A DIN-rail candidate with a narrow mechanical footprint, but the buyer still owns the system load and installation requirements. Ask WEHO for the controlled documents for the ordered revision, then verify remote voltage and dynamic behaviour in the intended auxiliary-control circuit before release.
Questions fréquemment posées
Does a constant voltage power supply deliver a constant current?
No. It aims to regulate voltage within its operating limits while compatible loads draw current. Current demand, temperature and protection conditions still determine whether the operating point is acceptable.
Does NDR-120-24 provide 5 A from each repeated output terminal?
No additional independent 5 A outputs are established by the repeated terminals. The exact model is rated 24 V and 5 A; assess the connected total using the controlled specification and terminal instructions.
Why can a device receive less than the measured supply-terminal voltage?
Resistance in the outgoing cable, return path and connections produces a voltage drop under load. Measure at the demanding device as well as at the supply, with the same operating state and current recorded.
What load-step response does this guide verify for NDR-120-24?
None. It gives an acceptance-planning method, not a verified waveform or recovery time. Obtain applicable controlled performance information and evaluate the intended system against its devices’ voltage and timing requirements.
Can the adjustment control be used as remote voltage compensation?
The visible +V ADJ control does not establish remote sensing or automatic cable-drop compensation. Before changing the setting, assess every connected device’s permitted voltage and all branch conditions.
Do the printer and textile images prove powered compatibility?
No. They depict isolated mechanical preparation with disconnected terminals and dark equipment. They do not prove printer operation, cutting-drive supply, actual load compatibility or completed commissioning.
How should the source label and specification input ranges be handled?
The source photo’s nominal 100-240 VAC and 50/60 Hz text is preserved separately from the current specification’s operating 85-264 VAC and 47-63 Hz table. Confirm the ordered revision and resolve conflicting public information before electrical release.
