Elimination of time delay from shaft-position or speed transducer outputs

The output of angle transducers, including those used for synchronous-generator rotor angles, need to be filtered to give a d.c. signal, and a filter limits the transient response. The letter shows that, if the speed is also available as a d.c. signal, for example from the filtered output of some form of tachometer, the filter delay can be eliminated by mixing the angle and speed signals in proper transient and steady-state proportions. This mixing requires an operational amplifier. A delay-free speed signal can also be achieved, provided that a separate accelerometer signal is available.