Mean Well SE-350-24 Enclosed Switching Power Supply

A fan-cooled 350 W supply for 24 V panel loads

The Mean Well SE-350-24 is an enclosed AC/DC switching power supply that delivers 24 V DC at up to 14.6 A, a rated 350.4 W. It belongs to the SE-350 family, which Mean Well describes as a low-cost, high-reliability single-output series with a built-in DC cooling fan and an AC input range selected by a switch on the case. The 24 V model reaches a typical 87% efficiency and its output can be trimmed between 20 and 26.4 V with the front potentiometer.

Protection covers short circuit, overload, overvoltage and over-temperature. On overload the unit limits the current between 105 and 135% of rated output and recovers by itself once the fault is cleared. The fan is switched on and off by a thermal control, so it does not run at light load.

Technical specifications

Choosing the right input range and loading

The input selector matters more than it looks. The datasheet gives separate 90 to 132 VAC and 180 to 264 VAC ranges, and the static characteristic shows the permitted load falling as the input voltage drops toward the bottom of either range. Set the switch before first power-up, because a supply set to 115 V and connected to a 230 V line is not covered by the specification. DC input is possible from 254 to 370 VDC; the datasheet note says to connect the positive pole to the L terminal and the negative pole to N.

A 14.6 A rail suits groups of valve coils, contactor coils, relay boards, indicator lamps and I/O racks in a machine or small process skid. Total the continuous current of all loads and keep a margin: the output derating curve starts to reduce the allowed load as ambient temperature rises toward +60 C, and the fan only helps if the vents on the top and sides stay clear.

Mounting and wiring notes

The SE-350 is a chassis-mount unit with a screw-terminal block: terminals 1 to 3 take AC/L, AC/N and FG, and terminals 4 to 6 and 7 to 9 carry the DC output minus and plus. The mechanical drawing shows M4 and M3 mounting holes on the base and side. Leave clearance around the fan opening and the side vents, wire the FG terminal to protective earth, and use conductors sized for the 14.6 A output. Because the switching frequency is fixed at 90 kHz and the unit has a built-in fan, plan for a little acoustic noise and for periodic cleaning in dusty enclosures.

Key features

• Single 24 V output rated 14.6 A with front-panel adjustment from 20 to 26.4 V to compensate for cable voltage drop.
• Selectable 115/230 VAC input by switch, plus DC input from 254 to 370 VDC.
• Thermally controlled DC fan that runs only when cooling is needed.
• Protection against short circuit, overload, overvoltage and over-temperature.
• Typical efficiency of 87% and MTBF of 234.3k hours minimum to MIL-HDBK-217F at 25 °C.

Application examples

A 24 V, 350 W supply is a common choice for the control section of industrial panels. Typical loads include PLC and remote I/O racks, solenoid valve manifolds, relay and contactor coils, sensors and transmitters, small HMI terminals and LED panel lighting. In packaging lines, water treatment skids and building services panels, one SE-350-24 can feed a group of these loads from a single DIN-rail distribution.

Where a failure of the 24 V rail would stop a critical process, consider two supplies with a redundancy module, or a separate supply for safety circuits. The SE-350 has no built-in parallel or redundancy function, so external components are needed for this.

Operating in hot and dusty Gulf panels

Control panels in Oman and the GCC often see internal temperatures well above the outdoor shade temperature, especially outdoors or in un-cooled plant rooms. The SE-350-24 works from -20 to +60 °C but its output must be derated at higher temperatures according to the derating curve, so size the supply with extra margin when the cabinet runs hot. Mount the unit where its fan draws in the coolest air in the panel, and not directly above drives or other heat sources.

Because the fan moves air through the case, dust accumulates inside over time. In sandy locations, use filtered panel ventilation and include the supply in periodic cleaning with dry compressed air while the unit is isolated. Humidity is specified at 20 to 90% RH non-condensing, so anti-condensation heaters are useful in coastal panels that cool down at night.

Maintenance and troubleshooting

• If the output drops and recovers repeatedly, check for an overload or short; the unit limits current between 105 and 135% and recovers automatically.
• If the output is off and does not return, overvoltage protection may have operated; remove input power and re-apply it after checking the trim setting and wiring.
• Listen for abnormal fan noise and replace the supply or have the fan serviced before it fails.
• Measure the output under load during planned maintenance and readjust if cable drop has increased.

Documents and quotation

The attached Mean Well datasheet covers the whole SE-350 series, with the model table, derating curve, static characteristic and mechanical drawing. For a quotation on SE-350-24, send the quantity, the mains voltage and frequency at the site, the load current including start-up peaks, the cabinet temperature and any approvals you need. Related supplies are listed under Power Modules.