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Dramm AME fans are most often controlled in some manner, by an external computer.
Most typically, the fans are switched on and off by means of a relay in front of the speed controller. In this case, the external computer activates the relay utilizing an on/off output. In this instance, you will need both and on/off output for the computer and a relay capable of handling the load for the fans. Another method can be used to turn the fans on and off while offering the ability to control the speed as well. By using an analog output instead of an on/off output, no relay will be needed. Using either a 2-10vDC or 4-20mAmp signal the fan speed can be varied between the upper and lower limits set by the two potentiometers in the speed controller. However, when a signal below the range listed above (less than 2 vDC or 4 mAmp), the fans can be programmed to shut off. For more information concerning this method, please see this post. __________________ Kurt Becker Dramm Corporation 920/645.6417