What is a Tacho generator?

A tachogenerator is a sensor that is attached to a rotating shaft and outputs a DC voltage signal according to the rotation speed. It is used to detect the rotational speed of the shaft and is abbreviated as TG. The word tachogenerator comes from the Greek word tachos, meaning speed, and the device that measures engine speed is called a tachometer.

Application of Tacho generator

Tachogenerators are mainly used for rotation detection of mobile equipment. It has long been used in tachometers and speedometers for automobiles and ships. By attaching a tachogenerator to the rotating shaft of an engine, it is possible to calculate the speed from the number of revolutions. In recent years, an inexpensive and highly accurate pulse generator is often used as an alternative.

A tacho generator is a device for detecting rotation speed and rotation direction, and is mainly composed of the following parts.

1. Rotor
A rotor is a part that rotates with a rotating shaft. There is a coil wound inside, which consists of wires wrapped around the rotor core. As the rotor rotates, magnetic flux passes through the coil and an induced electromotive force is generated in the coil. Since the direction of this induced electromotive force changes depending on the rotation direction, it is possible to determine not only the rotation speed but also the rotation direction.

2. Brush (commutator)
Brushes are the parts that come into contact with the rotor of the tachogenerator. It has the role of switching the polarity of the voltage applied to the coil, and is mainly made of materials such as carbon. Brushes wear out with long-term use and require regular maintenance and replacement. If contact failure occurs due to improper contact, dirt, rust, etc., accurate rotation speed detection may not be possible.

3. Stator/Casing
The stator is a component that provides a magnetic field to the rotor, and permanent magnets are mainly used. When the rotor rotates in the magnetic field created by the stator, an induced electromotive force is generated in the coil.

The casing has the role of protecting the rotor and permanent magnets inside. Generally made of metal, they must be durable, heat resistant, and corrosion resistant. Steel and stainless steel are commonly used materials. An input/output connector is installed on the casing, which supplies the signal output from the tachogenerator to the outside. It also has holes and slits for mounting, and is used for mechanical fixing and wiring passages.

How a tacho generator works
The basic operating principle of a tachogenerator is that a rotor attached to a rotating shaft rotates, moving a coil in a magnetic field and generating a voltage. This generated voltage is proportional to the rotation speed, and the polarity of the voltage changes depending on the rotation direction. By analyzing this voltage signal, the rotation speed and rotation direction can be detected.

Importance of maintenance
The tacho generator has many mechanical parts and is prone to deterioration due to wear and dirt. In particular, the contact parts of brushes and electrodes require regular cleaning and replacement. With proper maintenance, stable performance can be maintained over a long period of time.

Tacho generator is an important device for accurately measuring the rotation speed of machinery, and is widely used in various fields such as industrial equipment, automobiles, elevators, etc.

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