Principle Of Operation
 
The Permanent DC Tachogenerator described here is basically a shunt field DC Generator which develops a voltage proportional to speed. However use of permanent magnet instead of electromagnet eliminates the need for a DC source and makes the device extremely reliable and stable. While the voltage induced by an ordinary generator may be generally proportional to speed, the output of a tachogenerator is required to be strictly proportional to speed to serve as a speed transducer. The accuracy of the TACHO decides the max. accuracy to which speed of a given machine can be controlled.
   
Construction
   
The Jayashree Tachogenerator incorporates the following special constructional features to retain high accuracy and extreme reliability even under arduous duty in aggressive environment.

• Housing duly heat treated and precision machined.
• The shaft made from alloy steel is heat treated, machined and precision ground to achieve optimum strength, rigidity and accuracy.
• Prelubricated and sealed precision ball bearings are used for long maintenance free life.
• Silver graphite brushes are used to minimize voltage drop at varying loads and speeds.
• Brush holders are precision machined to ensure smooth movement of brushes.
• Optimum brush pressure is maintained by specially designed spring mechanism.
• ALNICO V Magnet used to minimize linearity errors due to Temperature Variation.
• Temperature Compensation can be provided to ensure extreme accuracy even with wide fluctuation in Ambient Temperature.
• Commutator built with electrolytic grade workhardened copper segments moulded and machined to close tolerances to achieve sparkless commutation and minimum wear. Use of mica insulation between segments ensures maximum dielectric strength and stability.
• Armature built with special silicon steel stampings and wound with polyester grade class ‘F’ enamelled Cu wire and vacuum impregnated for high electrical and mechanical strength. Leads are hot staked to commutator segments for excellent electrical contact and mechanical bonding.
• The armature is dynamically balanced to ensure vibration free rotation, sparkless commutation and low ripple content.
• Teflon coated silver plated copper wire leads are used for connection between brushes and terminal board.
• Shaft extension available for Hand Tachometer speed measurement.

Features

• Robust Construction.
• Output Voltages upto 200 volts/krpm.
• High Linearity.
• Low Ripple.
• Maximum permissible speed upto 10000rpm depending upon the size and voltage constant.
• Temp. compensation available on request.

Application

Jayashree DC Tachogenerator is the ideal choice for accurate sensing and precise control of rotational speeds of variable speed drives used in paper, steel, machine tools, processing plants and in other engineering applications.