Online Electrical Engineering
EMF Equation of DC Generator
Parallel Operation of DC Generators
Self Excited DC Generators
Working Principle of Alternator
Construction of Alternator
Alternator Synchronous Generator | Definition and Types of Alternator
Armature Winding | Pole Pitch Coil Span Commutator Pitch
Armature Winding of Alternator
Winding Factor | Pitch Factor | Distribution Factor
Rating of Alternator
Derivation of Various Power Conditions in Alternators and Synchronous Motors
Phasor Diagram for Synchronous Generator
Armature Reaction in Alternator or Synchronous Generator
Principle of DC Generator
Construction of DC Generator | Yoke Pole Armature Brushes of DC Generator
Frog Leg Winding | Drum Winding | Gramme Ring Winding
Types of DC Generators
Characteristic of Separately Excited DC Generator
Characteristics of Series Wound DC Generator
Characteristic of Shunt Wound DC Generator
Applications of DC Generators
Magnetization Curve of DC Generator
DC Generators Performance Curves
Motor Generator Set | M G set
Wind Turbine | Working Types and History of Wind Turbine
Theory of Wind Turbine
Induction Generator | Application of Induction Generator
Motor Generator Set | M G set
A motor generator (M-G) set refers to a composite device consisting of a motor and a generator mechanically coupled through the common shaft. Practically a motor generator set is a system where a motor and a generator are connected or rather placed in a single circuit. It is a device used to convert electrical power from one form to another. That is mainly it converts electrical power to any other type of power. Motor generator set are also used to convert voltage, phase and frequency of power. They also find application in isolation of electrical loads from the supply line. Here is a pictorial representation of a MG set. Here a motor and a generator are coupled together using a single shaft; they are wound around a single rotor. Necessary condition for coupling is that rated speed of both motor and generator should be same.
The diagram of a motor generator set is shown below, Working Principle: From the above diagram we can see that in a typical motor generator set, the power is given externally to a motor and as a result the shaft of the motor rotates the rotor of the generator. That means, motor receives electrical energy input from the supply line. Its shaft rotates and since the generator shaft is mechanically coupled with it, the generator also receives its mechanical input through shaft. Thus generator also creates electrical output power or in other words generator converts the mechanical energy into electrical energy. Thus while the power at the input as well as output side is electrical in nature, the power flowing between the machines is in form of mechanical torque. This provides isolation of the electrical system as well as some buffering of power between the two electrical systems.
Conversions The motor generator set can be used for conversions of electrical power in various forms
- AC to DC – This is possible by using a AC motor (induction motor or synchronous motor) and a DC generator.
- DC to AC – This can be accomplished by using a DC motor and an AC generator.
- DC at some voltage level to DC at another voltage level.
- Alternating power at one frequency to Alternating power at another frequency
- Fixed AC voltage to variable or regulated AC voltage
- Single phase AC voltage to 3 phase AC voltage
Now days motor generator sets have been upgraded in many ways. Earlier these were used in the places where speed regulation is required highly like elevators, factories etc. Now day’s semiconductor devices are working as the motor generator set i.e. with the introduction of power semiconductors devices like thyristor or SCR?">thyristor, GTO, MOSFET etc. motor generator set are replaced by them. These conversions of power from one form to another can be brought about very easily. They are small and compact in size, losses are less and control is very easy.