A DIN-rail power supply can meet the nominal voltage and wattage requirements and still be a poor match for a control cabinet. The load may draw more current during start-up, the cabinet may run hotter than expected, or the housing may leave too little room for wiring.

For engineers and purchasing teams, selection starts with the application: the available input supply, the equipment connected to the DC output and the conditions inside the enclosure. The following five checks help turn those requirements into a practical model comparison.

1. Match the Electrical Ratings to the Load

First, establish the required output voltage and continuous current. Then check what happens when the equipment starts or when several loads switch on together. A steady-state load total does not describe these short-duration demands.

• Input supply: Check the available AC or DC voltage against the specified input range. A wide input range does not, on its own, describe performance during a supply interruption; review hold-up time separately if the equipment needs it.
• Load start-up and peak current: Identify the current demand, its duration and which loads start together. Compare these conditions with the selected model’s documented output capability.
• Output performance: Review output tolerance, regulation and transient response against the voltage limits of the connected equipment.

Keep AC input inrush separate from load-side starting current. Input inrush is the current drawn when the power supply itself is energized. Load-side starting current is drawn by equipment connected to its DC output. These are different checks in the system design.

Protection behavior also affects start-up. With hiccup protection, a supply shuts down during an overload and retries after a delay. A load with high starting current or substantial input capacitance may trigger repeated restarts. Check the documented protection mode and, where start-up is uncertain, test the intended load.

2. Check Available Output at the Cabinet Temperature

Efficiency determines how much of the input power becomes heat rather than useful output. For illustration, delivering 100 W at 90% efficiency produces about 11.1 W of conversion loss; at 95%, the loss is about 5.3 W. These are calculated examples, not ratings for a particular AIPUPOWER model.

The next step is to read the derating curve. A stated operating-temperature range does not necessarily mean that full rated output is available throughout that range. Use the temperature expected around the installed power supply, rather than the room temperature outside the cabinet.

• Check the available output at the expected ambient temperature and input voltage.
• Review the specified mounting orientation, ventilation and clearance requirements.
• Allow for nearby heat sources and the proposed arrangement of components inside the enclosure.

Compare efficiency figures at equivalent operating points where possible. Values taken from different output-voltage versions or test conditions are not a direct like-for-like comparison.

3. Check Cabinet Fit: AIPUPOWER SIP and SIML

Housing width matters when rail space is limited, but depth can be the tighter constraint in a shallow enclosure. Terminal access, cable routing and installation clearances also need space in the layout.

Our SIP series and SIML series offer different housing dimensions. The table below provides a starting point for comparing their space requirements.

Dimensions follow the series catalog listings. Use the selected model’s dimensional drawing to confirm axis orientation, mounting details and required installation clearances.

The SIP housings listed here have a smaller depth dimension, which may be useful in shallow cabinets. Several SIML models use a 30 mm housing width but require more depth. Choose between these layouts using the enclosure drawing, then check that the selected model also meets the electrical and thermal requirements.

4. Review Compliance and EMC Requirements

Identify the requirements of the target market and the finished equipment before approving the power supply. The documentation review may include applicable safety standards, insulation information, declarations of conformity and electromagnetic compatibility (EMC) test evidence.

For an EU-market application, review the applicable EU Declaration of Conformity and its product identification. CE marking is a declaration of conformity with the applicable requirements; it is not, by itself, an independent third-party approval. Any additional approvals required by the project should be checked separately.

For installations near switching motors, contactors or other sources of electrical disturbance, review the relevant immunity documentation. Where applicable, this includes electrostatic discharge (ESD), electrical fast transients (EFT) and surge. Test levels and configurations matter more than a general description such as “industrial grade.”

When reviewing an AIPUPOWER model for a project, contact our team to confirm the applicable documentation for the ordering code and intended market. Include the finished equipment’s requirements in that review; component documentation does not replace assessment of the complete system.

5. Keep the Approved Specification Clear

Once a model has been evaluated, record more than its nominal voltage and wattage. The approved specification should identify the ordering code, datasheet revision, dimensional drawing and any application-specific clarification used during selection.

This gives engineering and purchasing teams a common reference when placing repeat orders or reviewing a replacement. A proposed substitute needs to be checked for start-up behavior, protection response, thermal limits, dimensions and compliance—not accepted simply because its rated power is the same.

For ongoing projects, discuss availability, lead times and the handling of product changes before the first production order. Keep technical questions tied to the approved model so that later clarification can be traced back to the original design decision.

Selecting an AIPUPOWER DIN-Rail Power Supply

A useful shortlist starts with the load requirements and available cabinet space. From there, compare start-up capability, temperature derating, installation requirements and the documentation needed for the project.

Explore our SIP series and SIML series to compare available models, output options and housing dimensions.