A tacho generator is a precision generator used to sense mechanical speed of rotation of a motor. If such a 'tacho' is used and fed to an appropriate controller, then the controller can maintain motor speed very accurately under varying loads: by responding to the feedback signal, the controller automatically compensates for the varying load and maintains the motor at a constant speed.
Without a tacho generator, a speed range of maybe 10:1 may be accomplished. With careful setting up, maybe even 15:1.
With a tacho generator this can be extended easily to 30:1 or even 50:1 speed range.
True tacho generators are, however, expensive - so the facility is normally only found on expensive industrial controllers.
4QD's controllers of the Pro series can however be fitted with tacho feedback and the same system can also be used with the NCC series.
This is done by means of a small, inexpensive additional board which plugs into the expansion connector on the Pro or NCC controller.
It is however quite possible to use a much cheaper small permanent magnet as a tacho generator. See Speed stability and Tacho generator feedback in our FAQ sheet.
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