EVOLUTION OF GENERATORS

 Tachogenerator

• An electromechanical generator is a device capable of producing electrical power from mechanical energy usually the turning of a shaft?
• When not connected to a load resistance, generators will generate voltage roughly proportional to shaft speed With precise construction and design generators can be built to produce very precise voltages for certain ranges of shaft speeds making them suited as measurement devices for shaft speed in mechanical equipment.
• A generator designed and constructed for this use is called a tachometer or tachogenerator, By measuring the voltage produced by a tachogenerator you can easily determine the rotational speed of whatever it's mechanically attached to since a tachogenerator cannot produce a voltage when it’s not turning the zero cannot be live in this signal standard.
• Tachogenerators can also indicate the directions of rotation by the polarity of the output voltage, When a permanent-magnet style DC generator’s rotational direction is reversed, the polarity of its output voltage will switch. In measurement and control systems where the directional indication is needed this provides an easy way to determine that.