UPS & Power Supply Cooling Fan

A UPS is a sealed box full of heat: the inverter, the rectifier and the battery string all lose energy in the same cabinet, and the fan is usually the only moving part in it. YUNFAN Power builds 12 V, 24 V and 48 V DC fans and 110/220 V AC fans for UPS modules, rectifiers, switching power supplies and battery cabinets — from a 60 mm fan cooling a control board to 172 mm fans pulling air across an inverter heat sink.

Part of: cooling fan applications · also relevant to telecom cabinets.

What a UPS fan actually has to survive

Continuous duty at full speed — the fan runs whenever the UPS is on line, which for a data-centre unit means years of uninterrupted rotation. Bearing life, not peak airflow, decides the warranty.
45–60 °C inlet air — exhaust air from the inverter stack is routinely 20 °C above room temperature. Standard sleeve bearings dry out in this band; dual ball or hydraulic bearings do not.
Acoustic limits in occupied rooms — a 1–3 kVA UPS often sits under a desk or in a small server room, so a 120 mm fan at moderate speed is preferred over a 80 mm fan screaming at 4,000 rpm.
Silent-failure protection — if the fan stops, the batteries cook before anyone notices. FG tachometer output or RD locked-rotor alarm lets the controller raise a fault.

Fan sizes and voltages for UPS and power supplies

Frame	Typical position	Voltage	Models
60–80 mm	control board, bypass path, small charger	12 V, 24 V DC	DC 6025, DC 8025
92–120 mm	IGBT tunnel, inverter heat sink	12 V, 24 V, 48 V DC	DC 9238, DC 12038
120 mm AC	1–3 kVA line-interactive UPS	110 V, 220 V AC	AC 12038
172 mm	large UPS, rectifier bank	24 V, 48 V DC / 220 V AC	DC 17251, AC 17251
225–280 mm	modular UPS frame, battery room	220 V, 380 V AC	AC 22580, AC 28080

Where UPS cooling goes wrong

The fan blows into a closed plenum. With no dedicated outlet the air recirculates inside the cabinet and the net gain is close to zero. Intake and exhaust need separate paths, and the exhaust should not sit directly above the intake.
A 40 °C fan is specified into a 55 °C cabinet. The bearing grease is specified at the wrong temperature, the fan seizes at 12–18 months, and the failure is blamed on the fan brand rather than the selection.
No feedback signal. The controller cannot tell a stopped fan from a slow one, so the first alarm is a battery over-temperature shutdown.

How to specify your UPS fan in five numbers

Inlet ambient at the fan, measured under load — not the room temperature.
Required airflow at the system impedance, ideally from a pressure–flow curve you already have.
Available rail and tolerance: 12 V, 24 V or 48 V DC, or 110/220 V AC.
Signal needed: none, FG tachometer, RD alarm, PWM speed control or temperature-controlled speed.
Connector, lead length and mounting hole pattern, so the fan drops into the existing harness.

Questions we get from UPS designers

Do you build 48 V DC fans for rectifier and telecom rails?

Yes. 24 V and 48 V DC windings are available across the DC axial range, including 120 mm and 172 mm frames. Specify the voltage and the tolerance your rail holds in the drawing, and we will match the winding to it.

Can the fan report a failure to the UPS controller?

FG square-wave tachometer output and RD locked-rotor alarm are both standard options on our DC fans, along with PWM speed regulation and temperature-controlled speed. Tell us the logic level your controller expects and we will confirm the interface.

What bearing should I choose for a 55 °C cabinet?

Dual ball bearing in most cases. It tolerates the temperature and gives a predictable L10 figure that you can put in a warranty calculation. Sleeve bearings are cheaper and quieter when new, but the lubricant migrates at sustained high temperature.

Tell us the rail, the ambient and the space you have, and we will propose two fan options with the pressure–flow reasoning. Send your requirement.