2. DEFENITION
Tacho generator is a device which is used for
measuring the speed of shaft and converting into
a voltage so that it can be measured.It converts
angular velocity into voltage.
They are used to measure the speed of electric
motors, engines, and the equipment they power
:Conveyor belts, machine tools, mixer,fans,etc.
3. PRINCIPLE
The major principle for tachogenerator is that the
relative motion between a Magnetic field & a
conductor results the voltage in that conductor
4. Types of Tacho generator
DC Tachogenerator - A DC tachogenerator is a
small DC generator ,which generate electrical
voltage corresponding to the speed of rotating
machine.
AC Tachogenerator – The AC tachogenerator is a
small brushless alternator with a rotating multi-
pole permanent magnet. The output voltage is
again measured by a voltmeter although the
varying frequency will affect the accuracy of this
instrument.
5.
6.
7. CONSTRUCTION
An Armature is rotating type & this magnet is
fixed type.
Armature is coupled to a machine whose velocity
is to be measured.
It consists of commutator and brushes is
connected to armature.
Output is connected to Moving Coil (MC) type
Voltmeter
8. WORKING
When the armature is stationary there is no relative motion between the
magnetic field and the armature winding.
Hence the output voltage is Zero.
As the armature speed increases the relative motion also increases.
The output voltage is induced in the armature winding.
The magnitude of this voltage is propotional to the speed of armature.
A commutator and brush are connected in the armature to give the DC
output voltage.
The polarity of output voltage indicates the direction of rotation.
This output voltage is measured with the help of moving coil voltmeter
calibrated in terms of speed.
