supplies (if any), it’s important to look at both the total heat load and the distribution of the heat sources. The former can be checked fairly simply by looking at the supply’s rating, as the maximum heat generated (watts) cannot exceed that value. Next, the ambient temperature is factored into the analysis. However, the unconstrained arrangement of the various modules on the DIN rail means that a higher dissipation module (typically a power supply, but not necessarily) might be situated adjacent to a heat- sensitive module, so the thermal floor plan must be checked as well. Engineering is largely about trade-offs and standards, and no solution or format is “perfect” for every application. Despite its flexibility, the DIN rail approach is not the “universal” answer to using larger, heavier units such as power supplies. In practice, the DIN rail is suitable for dissipation up to about 1000 W in a closed, rack width enclosure, unless substantial forced air or active cooling is available. If larger supplies are used, they are sometimes mounted “off rail” due to their weight and size, but there also are many rail-compatible ones for relatively higher power ratings.
Also, the DIN rail and its supplies may not be a good choice when the power supply or other modules need to have multiple user readouts for parameters such as voltage and current, indicators for various status and fault conditions such as power good or overload, or I/O status and alarms. This is because DIN modules tend to be narrow with more use of depth than width, thus limiting the availability of front panel space for user readouts. Modules with more indicators and readouts are available, but they are generally wider and take up more of the rail real estate. Fortunately, the flexibility and non-bus nature of the DIN rail allows for an easy solution to this problem by simply using two (or more) rails, with one mounted below the other and linked by cabling as needed. Conclusion The DIN rail mounting system standard offers flexibility and ease of use for designers, vendors, and buyers of industrial systems and industrial system modules. It supports modules ranging from basic power supplies through advanced sensor interfaces to PLCs, with thousands of DIN- compatible products available from hundreds of vendors.
References 1. Hackaday, “The DIN Rail and How it Got That Way” 2. International Electrotechnical Commission, “IEC 60715:2017: Dimensions of low-voltage switchgear and controlgear - Standardized mounting on rails for mechanical support of switchgear, controlgear and accessories” 3. ATMCO LLC, Model LB-100 DIN Rail Cutter
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