AC tachogenerator DC tachogenerator The AC tachogenerator is use to measure speed only in one direction only. The DC tachogenerator is. A.C. Tachogenerator • 2. D.C. Tachogenerator; 6. CONSTRUCTION • An Armature is rotating type & this magnet is fixed type. • Armature is. The DC tachometer works on the principle that when the closed conductor moves in the The drag cup Tachogenerator generates the ripple free output voltage.

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Quote of the day. The DC tachometer generator uses the commutator tachogwnerator brushes which have many disadvantages. When not connected to a load resistance, generators will generate voltage roughly proportional to shaft speed. Although a voltage divider could theoretically be used with a tachogenerator to extend the measurable speed range in the volt scale, it is not advisable to significantly overspeed a precision instrument like this, or its life will be shortened.

Difference between AC tachogenerator and DC tachogenerator – Polytechnic Hub

When the shaft tachogenrator the machine revolves, the armature of the tachogenerator revolves in the magnetic field producing e. The moving coil voltmeter measures the induced emf.

Design challenges and improvement techniques for SAR driver circuit Design challenges and improvement techniques for SAR driver circuit. Your email address will not be published. Thus it is mostly used for measuring the rotational speed of the shaft. The rotor of the tachometer is made with thin aluminium cup, and it is placed between the field structure.


An electromechanical generator is a device capable of producing electrical power from mechanical energy, usually the turning of a shaft. The relative motion induces the EMF in the coil which is placed between the constant magnetic field of the permanent magnet. The develops EMF is directly proportional to the speed of the shaft. The rotation of rotor between the magnetic field induces the voltage in the sensing winding.

The electrical tachometer converts the angular velocity into an electrical voltage.

The polarity of the tachogeneratpr voltage determines the direction of motion of the shaft. The armature of the D. The constant of proportionality K t is generally linear within a large dynamic range but does vary in relation to: By measuring the voltage produced by a tachogenerator, you can easily determine the rotational speed of whatever its mechanically attached to. Circuit Globe All about Electrical and Electronics.

D.C Tachogenerators

One of the more common voltage signal ranges used with tachogenerators is 0 to 10 volts. The polarity of output voltage indicates the direction of rotation.

In the tachogenerator case the magnetic flux density B and the loop length l are constants, so the output voltage V o is proportional to the shaft angular velocity W, as required and a shown previously in eqn 1. Its main drawbacks, on the other hand, are that it has an analogue output which requires AID conversion when interfaced to a computer ; the output can suffer from large fluctuations, and it has a shorter operational life. The theiry of the DC generator revolves between the constant field of the permanent magnet.

Thus, the commutator and brushes are absent in AC tachometer generator. The armature of the tachogenerator is coupled to the machine whose tacyogenerator is to be measured. Tachogemerator with Ads Link x The magnitude of the induced emf is proportional to the shaft speed.


Figure 1 Typical transfer characteristic of tachogenerator. C tachogenerator is shown in below figure.

I have prepared a list of instrumentation and control engineering based companies in India, which you should must know. Permanent magnet, armature, commutator, brushes, variable resistor, and the moving coil voltmeter are the main parts of the DC tachometer generator. This phenomena is therefore the same which gives rise to the back electromotive force b. These variations are usually amply documented in the manufacturer data sheets and do not present a problem.

The magnitude of the induces emf depends on the flux link with the conductor and the speed of the shaft. And i am starting it from the scratch. The series resistance is used to limit the current under output short circuit condition. The stator of the generator consists two windings, i. The rotation tjeory the emf in the coil.

Depends on the natures of the induced voltage the electrical tachometer is categorized into two types.

The DC tachometer works on the principle that when the closed conductor moves in the magnetic field, EMF induces in the conductor. A very basic transducer which is always useful in the field of instrumentation, I The AC tachometer generator designs for reducing the problems.

Mechanical and electrical are the two types of the tachometer.