Advantages of Conduction-Cooled Power Supplies

Most medium to high power supplies use fans to help dissipate internal heat generated by inefficient AC to DC conversion. Because fans are electromechanical devices, they reduce the system's MTBF (mean time between failures) and increase maintenance costs.
 

The attached picture shows a power supply that operated for many years at a postal station (where mail was automatically processed and sorted). As shown in the picture (after the fan was removed), the shredded paper and flying dust contaminants were sucked into the power supply through the fan, eventually causing the fuse to blow.

As we might expect, a proper maintenance program for any fan-cooled power supply requires regular inspection, removal of old fans and replacement with new ones.

A new type of conduction-cooled power supply has been developed that does not rely on fans for cooling. Instead, it cools by conducting internal heat to an external metal structure or housing, which acts as a large heat sink surface.

The second photo shows TDK-Lambda's new CPFE1000F series, a conduction-cooled, 1,000 W AC-DC power supply. (A 500 W model is also available.) All heat is conducted to the power supply's aluminum plate, which can be easily mounted to a metal enclosure or cold plate for cooling.

In some applications, these conduction-cooled devices are mounted on liquid-cooled cold plates, which are made of metal and have internal serpentine channels through which liquid circulates as it removes unwanted heat. The end result is a system that runs much quieter, has reduced maintenance costs (no dust buildup and fan wear), and has an extended MTBF.

I recently visited a TV broadcast station that consumes approximately 100 kilowatts of power. Here, in separate areas, there are both traditional fan-cooled systems and the latest generation systems. The new generation cooling system uses conduction-cooled power supplies and RF amplifiers, cooled by liquid flow cold plates. During operation of the traditional fan-cooled system, the noise can be heard so loud that people within 100 feet of the system must wear hearing protection. In contrast, in other operating areas with the new liquid cooling system, the noise level is so low (similar to an office environment) that hearing protection is not required.