Two form factors, two installation approaches
Industrial power supplies are made in two main form factors. The first is the DIN rail mount: a narrow profile unit with snap-on clips that installs in line with circuit breakers and relays on a standard 35 mm DIN rail. The second is the enclosed (or open-frame chassis) type: a rectangular metal housing with mounting holes for fixing to any flat surface inside the cabinet.
Both deliver industrial quality and comparable service life. The difference lies in installation convenience, cost, power level, and where the unit sits inside the cabinet.
DIN rail power supplies: when they are the right choice
DIN rail units (Mean Well HDR, MDR, NDR, DR series; Delta DRL, DRP) snap onto the rail in seconds without tools. They belong alongside circuit breakers, relays, contactors, and other DIN-mounted apparatus. This keeps installation and servicing tidy: everything is accessible from the cabinet front, cable labelling is straightforward, and replacement requires no unscrewing of anything extra.
The typical application range for DIN rail units is up to 240-480 W. This is the power band where the choice between DIN and enclosed is most relevant. For small control cabinets where 90% of the equipment is already on DIN rail, a DIN rail power supply is the natural fit.
One detail worth noting: the compact DIN housing means tighter internal component packing and, as a result, a more demanding thermal environment. Most models specify a minimum clearance above and below for ventilation. Check the datasheet — at 50°C some models derate by 20-30%.
Enclosed power supplies: when they are the better choice
Enclosed units (Mean Well LRS, RSP series; Delta PMT, PMC) mount on four screws and can go anywhere inside the cabinet: side wall, back panel, or a separate mounting plate. This provides greater flexibility in cabinet layout.
The key advantage of enclosed over DIN rail at the same power rating is lower cost per watt. The higher the power requirement, the more pronounced this difference becomes. Enclosed units are the common choice in remote power distribution nodes, power racks, and anywhere a high output current is needed within a tighter budget.
Within the enclosed category there are also panel-mount models (PMC) — these sit flush with the front or mounting panel with only the terminal or indicator visible from the outside. They are used in operator panels and custom enclosures.
Comparison table
| Parameter | DIN rail | Enclosed |
|---|---|---|
| Installation | Tool-free snap-on to rail | 4 screws, any flat surface |
| Typical series | HDR, MDR, NDR, DR (Mean Well); DRL, DRP, DRM (Delta) | LRS, RSP (Mean Well); PMT, PMC (Delta) |
| Power range | 15-480 W | 50-480+ W |
| Cost per watt | Higher (DIN housing costs more) | Lower at equivalent power |
| Active PFC | Available on NDR, MDR-100; DRP, DRM | Available on RSP; not on LRS, PMT |
| When to choose | DIN-heavy cabinet, up to ~240 W, service convenience | Higher power, budget-limited, remote power node |
Cost per watt compared — a real 24 V example
A concrete example is more useful than an abstract rule. Consider two 24 V power supplies from the same brand:
- Mean Well LRS-150-24 — 150 W, 6.5 A, enclosed, no PFC. Price: 771 UAH. Cost per watt: ~5.1 UAH/W.
- Mean Well NDR-120-24 — 120 W, 5 A, DIN rail, no PFC. Price: 1,252 UAH. Cost per watt: ~10.4 UAH/W.
The DIN rail NDR-120-24 costs roughly twice as much per watt as the enclosed LRS-150-24. This is not a construction flaw — it is what you pay for convenient installation and a compact DIN profile. If the cabinet is already organised around DIN rail and orderly wiring matters to you, the premium is justified. If the goal is to minimise the cost of a high-current power supply, enclosed is the better choice.
For reference, the LRS-100-24 (4.5 A, 640 UAH) offers an even lower cost per watt in the enclosed segment.
DIN rail supplies in a DIN-heavy cabinet: the system view
A cabinet where all components — breakers, relays, a DIN-mounted VFD, a controller — are already on rail naturally calls for a DIN rail power supply too. Benefits include:
- Uniform installation and removal without disturbing cable connections.
- All terminals and labels at the same horizontal level along the rail.
- Quick replacement without removing cabinet screws.
The HDR-60-24 series (2.5 A, 868 UAH) suits small cabinets with modest loads. For higher current, NDR-240-24 (10 A) or NDR-480-24 (20 A) fit on the same rail.
For more guidance on power distribution inside a cabinet, read How to choose a power supply for a control cabinet and Which voltage to choose for a power supply. Full range: power supplies, DIN rail, Mean Well, Delta.
If your requirement does not fit a standard model — send us your load list and we will size the solution within one working day.
