What is a DIN rail power supply?

A DIN rail power supply is an AC/DC power supply built into an enclosure that clips onto a standard 35mm DIN rail (TS35) inside a control panel or cabinet. It converts the incoming mains supply — typically 230V AC in the UK — into a regulated low-voltage DC output, most commonly 12VDC or 24VDC, to run PLCs, sensors, relays, actuators and instrumentation on the same rail as the rest of the control gear.

What are DIN rail power supplies used for?

They are the standard method of powering industrial control panels: PLC and I/O racks, machine safety circuits, process instrumentation, building management and access control, HVAC controls, and factory automation. The DIN rail format keeps the supply serviceable, tool-free to replace and wired into the same terminal layout as the rest of the panel.

Should I use a 12V or 24V DIN rail power supply?

24VDC is the industrial default: nearly all PLCs, sensors, solenoids and safety relays are specified at 24V, and the higher voltage means lower current and thinner cable for the same power. Choose 12VDC when the connected equipment is explicitly 12V — typically CCTV, access control, telecoms and some marine or vehicle-derived hardware. Never run 12V equipment from a 24V rail without a DC/DC converter.

How do I size a DIN rail power supply?

Total the continuous current draw of every connected device, add at least 25% headroom for future additions, then check the in-rush requirement of any capacitive or inductive load. If the panel sits in an enclosure above 45–50°C ambient, apply the manufacturer's derating curve — a 5A supply may only deliver 3.5A at 60°C. Sizing to the derated figure, not the nameplate figure, is the single most common specification error.

Can two DIN rail power supplies be connected in parallel?

Only if the supply is rated for parallel operation or you fit external redundancy diodes. Parallelling two units that do not current-share will make one supply carry the whole load while the other idles, which shortens the life of both. For genuine redundancy use an N+1 arrangement through a redundancy module so a single failed unit does not drop the rail.

What is the difference between a DIN rail power supply and a DIN rail transformer?

A DIN rail transformer is a magnetic device that changes AC voltage to another AC voltage and provides isolation only. A DIN rail power supply rectifies and regulates the output to a stable DC voltage, holds it constant as the load changes, and adds protection features such as over-current, over-voltage, short-circuit and over-temperature shutdown.

What approvals should an industrial DIN rail power supply carry?

For UK and EU industrial installation, look for EN/IEC 62368-1 (safety), EN 61204-3 (EMC for low-voltage power supplies) and UKCA/CE marking. Machinery applications frequently also call for EN 60204-1 compliance at panel level. Medical equipment requires EN 60601-1, which is a different and stricter standard — a general industrial supply cannot be substituted.

Do Pulsar supply DIN rail mounting for standard power supplies?

Yes. Alongside natively DIN-mounted units we hold DIN rail brackets that convert many chassis and enclosed Mascot power supplies and chargers to TS35 mounting, and our engineers can fit them and test the assembly before dispatch. Contact our technical team with your model number and we will confirm the correct bracket.

DIN rail power supplies: how to specify 12V and 24VDC units

A practical specification guide for panel builders, machine builders and controls engineers — written by the UK technical distributor of Mascot power. What the ratings actually mean, where the common sizing mistakes are, and how to choose between 12V and 24VDC.

A DIN rail power supply is an AC/DC supply housed in a module that clips directly onto the 35mm top-hat (TS35) rail running through a control cabinet. It takes the incoming 230V AC mains and delivers a regulated DC rail — almost always 24VDC, sometimes 12VDC — to the PLC, I/O, sensors, relays and instrumentation mounted alongside it.

The format matters as much as the electronics. Because the supply mounts on the same rail and wires into the same terminal layout as the rest of the panel, it can be swapped in minutes without rework, and the whole control system stays documented on one drawing. That serviceability is why DIN rail has been the industrial default for three decades.

Where Pulsar differs from a broadline catalogue is that we specify against your application rather than shipping a part number. We hold UK stock, our engineers will confirm sizing and derating against your cabinet conditions, and where no standard unit fits we modify or commission one.

What to check before you specify

Output voltage and tolerance: 24VDC for standard industrial control, 12VDC for CCTV, access control and telecoms. Check the adjustment range — most quality supplies trim ±10% so you can compensate for volt-drop on long DC runs.
Derated current, not nameplate current: Enclosure temperature is the limiting factor. Read the derating curve and size against the current available at your worst-case cabinet ambient, then add 25% headroom for future load.
In-rush and peak capability: Contactors, solenoids and capacitive loads draw many times their steady-state current at switch-on. A supply with a defined peak-power window rides through this without tripping into hiccup mode.
Rail width and TS35 fit: Panel space is finite. Compare the module width in mm and confirm the clip suits the 35mm top-hat rail you are using; some low-profile units also need clearance above and below for convection.
Protection and diagnostics: Short-circuit, over-current, over-voltage and over-temperature protection should be standard. A DC-OK relay contact or LED lets the panel report a failed supply instead of failing silently.
Approvals for the application: EN/IEC 62368-1 and EN 61204-3 for industrial. EN 60601-1 where the panel forms part of medical electrical equipment — this is not interchangeable with an industrial-only approval.

12VDC or 24VDC — choosing the rail voltage

Comparison of 12VDC and 24VDC DIN rail power supply applications
Consideration	12VDC	24VDC
Typical loads	CCTV, access control, telecoms, marine	PLCs, sensors, solenoids, safety relays
Current for 100W	8.3A — heavier cable, more volt-drop	4.2A — thinner cable, longer runs
Component availability	Narrower industrial range	Industry standard — widest choice
Mixed-voltage panels	Run a single 24VDC rail and derive 12V locally with a DC/DC converter rather than running two mains-fed supplies.

Where to go next

Replacing a discontinued unit from another manufacturer? Our cross-reference tool maps legacy part numbers to current equivalents, and the Mascot range overview covers the full portfolio we stock.

DIN rail power supply FAQs

Not sure which unit fits your panel?

Send us the load list and cabinet ambient and our engineers will size the supply, confirm the derating and quote UK-stocked options — usually the same working day.

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