WHAT IS AN ELECTRICAL MACHINE?

AN ELECTRICAL MACHINE IS A DEVICE THAT CONVERTS MECHANICAL ENERGY INTO ELECTRICAL ENERGY AND VICE VERSA. FOR EX. GENERATOR AND MOTOR. HOWEVER, TRANSFORMER IS A TYPE OF MACHINE THAT DOES NOT CONVERT ONE FORM OF ENERGY INTO OTHER BUT IT DOES CONVERTS ONE AC VOLTAGE LEVEL INTO ANOTHER AC VOLTAGE LEVEL.
AN ELECTRICAL MACHINES PLAYS VITAL ROLE IN NOT ONLY INDUSTRIES BUT ALSO IN OUR DAILY LIFE. ELECTRICAL MACHINES ARE USED IN FAN, AC, HAIR DRYER, VEHICLES, TOYS, ETC WHICH WE USE IN DAILY WITHOUT THEM OUR LIFE MORE LIKELY TO BE STOPPED.

TYPES OF ELECTRICAL MACHINES:

ELECTRIC GENERATOR - 

AN ELECTRIC GENERATOR IS A MACHINE THAT CONVERTS MECHANICAL ENERGY INTO ELECTRICAL ENERGY. IT WORKS ON THE PRINCIPLE OF ELECTROMAGNETIC INDUCTION. THIS STATES THAT WHENEVER A ROTATING CONDUCTOR PLACED IN A MAGNETIC FIELD IT CUTS THE MAGNETIC FIELD WHICH INDUCED EMF(ELECTROMOTIVE FORCE) IN THE CONDUCTOR.

EMF (ELECTROMOTIVE FORCE) IS NOTHING BUT A VOLTAGE OR ELECTRIC POTENTIAL. THAT CAUSES CURRENT TO FLOW THROUGH A CONDUCTOR.

GENERATOR IS MADE UP OF A ROTOR AND A STATOR. MECHANICAL ENERGY IN THE FORM OF ROTATION IS PROVIDED TO THE ROTOR BY MEANS OF PRIME MOVERS SUCH AS, TURBINES LIKE, STEAM TURBINE, WIND TURBINE, WATER TURBINE, ETC. ALSO BY IC ENGINES, ETC.

TYPES OF ELECTRICAL GENERATOR -

• AC GENERATOR OR ALTERNATOR = THIS GENERATORS CONVERTS MECHANICAL ENERGY INTO AC CURRENT. ALTERNATORS HAVE STATIONARY ROTOR AND ROTATING FIELD OR STATOR.

• SALIENT POLE TYPE - THIS ALTERNATOR USED FOR LOW AND MEDIUM SPEED BECAUSE IT HAS LARGE NUMBER OF POLES PROJECTING OUT OF ITS PERIPHERY. THIS ALTERNATORS HAVE LARGE DIAMETER AND SHORT AXIAL LENGTH.

• NON-SALIENT OR CYLINDRICAL TYPE - THIS ALTERNATOR HAS SHORT DIAMETER AND LARGE AXIAL LENGTH OF ROTOR, WHERE THE FILED WINDING IS PLACED INSIDE THE TOOTHED TYPE SLOTS PRESENT ON ITS OUTER PERIPHERY. THUS IT CAN BE USED AT HIGH SPEED. IT HAS ONLY 2 OR 4 NUMBER OF POLES.

•  DC GENERATOR = THIS GENERATOR CONVERTS MECHANICAL ENERGY INTO DC CURRENT. DC GENERATORS HAVE ROTATING ROTOR AND STATIONARY FIELD.

• SELF EXCITED DC GENERATOR - IN THIS TYPE FIELD COIL IS CONNECTED WITH ARMATURE IN EITHER SERIES OR PARALLEL OR SERIES-PARALLEL COMBINATION. 

• SERIES GENERATOR - FIELD WINDING IS CONNECTED IN SERIES WITH ARMATURE WINDING.

• SHUNT GENERATOR - FIELD WINDING IS CONNECTED IN PARALLEL WITH ARMATURE WINDING.

• COMPOUND GENERATOR - FIELD COILS ARE CONNECTED IN SERIES AND PARALLEL WITH THE ARMATURE WINDING.

• SHORT SHUNT GENERATOR.

• LONG SHUNT GENERATOR.

• SEPARATELY EXCITED GENERATOR  - IN THIS TYPED OF GENERATOR THE FIELD WINDING DOES NOT COME IN CONTACT WITH ARMATURE WINDING PHYSICALLY, THE SOURCE IS SEPARATELY PROVIDED TO FIELD WINDING.