Construction & Working of A.C. Tachometer Generator

Construction & Working of A.C. Tachometer Generator Points : Construction & Working of A.C. Tachometer Generator In order to overcome some of the difficulties in d.c. tachometer generators, the a.c. tachometer generators are used. These tachometer generators have rotating magnet which may be either a permanent magnet or an electromagnet. The coil is wound on the stated and therefore the problems associated with commutator (as in d.c. tachometer) are absent.

The rotation of the magnet causes an e.m.f. to be induced in the stator coil. Te amplitude and frequency of this e.m.f. are both proportional to the speed of rotation. Thus either amplitude or frequency of induced voltage may be used s a measure of rotational speed.

When amplitude of induced voltage is used as a measure of sped, the following circuit. The output of a.c. tachometer generator is rectified and is measured with a PMMC instrument.