DC VS AC

AC 400 HZ or 28 VDC brushless?

In the high reliability aerospace market AC 400 Hz fans are less expensive  than 28 VDC brushless fans with the same performance. On a jet aircraft where presumably both types of current are available some people ask why go with 28 VDC. Obviously it may just be a matter of convenience. Transformer rectifier units typically use  AC 400 Hz fans because the TRU has AC 400 hz input.  On the other hand the fan may be cooling an electronics box which is running on 28 VDC and there is 400 Hz AC available nearby. Another reason would be the need for a signal to indicate the speed of the fan or whether it is turning at a minimum speed necessary to cool the box.These signals, commonly known as fan performance sensors or low speed warning require DC current. You can have a speed sensor on an AC fan but you have to power it with DC normally. AC fan speed is controlled by the frequency. DC fan speed can vary with the voltage. DC fan electronics can have all kinds of built in features like soft start to limit inrush current.

Dearborn Electronics

DEARBORN ELECTRONICS Plastic film capacitor manufacturer, Dearborn Electronics of Longwood Florida has been acquired by Exxelia, parent company of Eurofarad (plastic film and ceramic capacitors), SIC SAFCO (aluminum electrollytic capacitors) and Firadec (Tantalum Capacitors) . Dearborn fits in perfectly with the Exxelia market focus of niche products for specialized markets like aerospace, defense, down hole oil exploration and medical technology. In order to better serve the US market particularly defense applications where ITAR restrictions limit access to Exxelia's technology Dearborn Electronics engineers will in the future be able to provide technical support for all the Exxelia product lines in the USA. Dearborn will enhance the Firadec we tantalum presence in the USA by performing screening comparable to Mil-C-39006 Allied International is now a fully authorized Dearborn Electronics distributor and will continue to serve our existing Eurofarad, SIC SAFCO and Firadec customers going forward.