INDUCTION GENERATOR

INDUCTION GENERATOR

• WHEN A SQUIRREL CAGE INDUCTION MOTOR IS ENERGIZED FROM A THREE PHASE POWER SYSTEM AND IS MECHANICAL DRIVEN ABOVE ITS SYNCHRONOUS SPEED, IT WILL DELIVER POWER TO THE SYSTEM

• AN INDUCTION GENERATOR RECEIVES ITS EXCITATION (MAGNETIZING CURRENT) FROM THE SYSTEM TO WHICH IT IS CONNECTED.

• IT CONSUMES REACTIVE POWER (KVAR) AND SUPPLIES ONLY REAL POWER (KW) TO THE SYSTEM.

WORKING OF A INDUCTION GENERATOR

• CONSIDER AN AC SUPPLY IS CONNECTED TO A STATOR TERMINALS OF  AN INDUCTION MACHINE. ROTATING MAGNETIC FIELD PRODUCED IN THE STATOR PULLS THE ROTOR TO RUN BEHIND IT. ( THE MACHINE IS ACTING AS MOTOR ).

• IF THE ROTOR IS MADE TO ROTATE AT SPEED MORE THEN SYNCHRONOUS SPEED BY MEANS OF PRIME MOVER, THE SLIP BECOMES NEGATIVE.

• THE ROTOR CURRENT IS GENERATED IN THE OPPOSITE DIRECTION, DUE TO THE ROTOR CONDUCTORS CUTTING STATOR MAGNETIZING FIELD

• THIS GENERATED ROTOR CURRENT PRODUCES A ROTATING MAGNETIC FIELD IN THE ROTOR WHICH PUSHES ( FORCES IN OPPOSITE WAY ) ON TO THE STATOR FIELD

• THIS CAUSES THE STATOR VOLTAGE WHICH PUSHES CURRENT FLOWING OUT OF THE STATOR WINDING AGAINST THE APPLIED VOLTAGE.

• THUS THE MACHINE IS NOW WORKING AS AN INDUCTION GENERATOR ( ASYNCHRONOUS GENERATOR )

USED IN WINDMILLS...

THIS TYPE OF GENERATOR HELPS IN CONVERTING THE UNCONVENTIONAL SOURCES OF ENERGY INTO ELECTRICAL ENERGY...

•  IT IS LESS EXPENSIVE AND MORE READILY AVAILABLE.THAN SYNCHRONOUS GENERATOR.

• IT DOES NOT REQUIRES A DC FIELD EXCITATION VOLTAGE.

• IT AUTOMATICALLY SYNCHRONIZES WITH THE POWER SYSTEMS SO ITS CONTROLS ARE SIMPLER AND LESS EXPENSIVE .

• IT IS NOT SUITABLE FOR SEPARATE ISOLATED OPERATION.

• IT CONSUMES RATHER THAN SUPPLIES MAGNETIZING KVAR.

• IT CANNOT CONTRIBUTE TO THE MAINTENANCE OF SYSTEM VOLTAGE LEVELS.

• IT HAS A LOWER EFFICIENCY.