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RECTIFICATION (A PROCESS OF CONVERTING A.C TO D.C BY A RECTIFIER (WHAT IS…
RECTIFICATION
A PROCESS OF CONVERTING A.C TO D.C BY A
RECTIFIER
WHAT IS A RECTIFIER??
UNIDIRECTIONAL CONDUCTOR
SYMBOL;
TYPES OF RECTIFIER;
THERMIONIC DIODE VALVE
SELENIUM
SEMICONDUCTOR (GERMANIUM/ SILICONE)
RECTIFIER BIASED
FORWARD BIAS
RACTIFIERS HAVE LOW RESISTANCE
RECTIFIERS CONNECTED TO A SUPPLIER
REVERSE BIAS
RECTIFIERS HAVE HIGH RESISTANCE
RECTIFIERS DOES NOT CONDUCT CURRENT
TYPE OF RECTIFICATION
HALF-WAVE RECTIFICATION
HOW??
WHEN A RECTIFIER IS CONNECTED SERIES WITH AN A.C INPUT AND A D.C LOAD
FIRST HALF
WHEN A CURRENT FLOWS, POTENTIAL IFFERENCE IS EQUAL TO RESISTANCE
SECOND HALF
CURRENT IS REVERSED IN BIAS DIRECTION, NO CURRENT FLOWS, POTENTIAL DIFFERENCE IS ZERO, RESISTANCE IS HIGH
FULL-WAVE RECTIFICATION
CENTER TAP FULL WAVE
CONSIST;
1) TWO RECTIFIERS
2) TRANSFORMERS WITH A CENTRE-TAPED SECONDARY
BASED ON THE DIAGRAM
DURING THE OTHER HALF OF THE SAME CYCLE...
POINT F IS POSITIVE WITH RESPECT TO POINT A AND O
RECTIFIER F CONDUCTS CURRENT (FORWARD BIASED)
CURRENT FLOWS THROUGH FEC AND O,F AND LOAD R
RECTIFIER B DOES NOT CONDUCT CURRET (REVERSE BIASED)
POINT O IS HALF OF POINT A
CURRENT FLOWS THROUGH ABC,OA, AND LOAD R
RECTIFIER E DOES NOT CONDUCTS CURRENT (POTENTIAL DIFFERENCE ACROSS FO IS REVERSE BIASED WITH RESPECT TO IT)
F IS A REFERENCE POINT (ZERO POTENTIAL)
BRIDGE FULL-WAVE RECTIFICATION
USED FOUR RECTIFIERS
BASED ON THE DIAGRAM...
FIRST HALF-CYCLE
POINT A POSITIVE
RECTIFIERS 1 AND 2 CONDUCT CURRENT (FLOW THROUGH ABC, DEF, LOAD R)
NEXT HALF OF THE SAME CYCLE
POINT F POSITIVE (RECTIFIERS 3 AND 4 ARE FORWARD BIASED)
CURRENT FLOWS THROUGH FEC, DBA, LOAD R
SMOOTHING RECTIFICATION USING CAPACITOR
A PROCESS OF PRODUCING A STEADY D.C FROM THE VARYING BUT UNIDIRECTIONAL OUTPUT OBTAINED FROM A HALF OR FULL-WAVE RECTIFIER
C1 IS A LARGE CAPACITOR (RESERVOIR CAPACITOR)
C1 TAKE A CHARGE AND DELIVER IT TO LOAD
SMOOTHING ACTION OF C1 DEPENDS ON..
SIZE OF THE CAPACITOR
VALUE OF LOAD
TIME BETWEEN EACH CYCLE
WHEN RECTIFIERS ARE PRODUCING PEAK OUTPUT (OA) 1)LOAD CURRENT IS FLOWING
2) CAPACITOR IS CHARGING
AFTER TIME T, RECTIFIERS OUTPUT DROPS OFF (AB) 1)CAPACITOR DISCHARGE AND PROVIDE LOAD CURRENT
CURRENT THROUGH LOAD IS MAINTAINED, POTENTIAL DIFFERENCE ACROSS LOAD, V IS ALSO MAINTAINED
CYCLE OPERATION IS REPEATED
V1 FLUCTUATING AT THE FREQUENCY TWICE OF THE SUPPLY
1 more item...
A FILTER CIRCUIT CONSISTING OF A CHOKE L
CHOKE = AN INDUCTOR WHICH HAS THE CIRCUIT PROPERTY OF OPPOSING ANY CHANGE IN CURRENT
WHEN A CHOKE IS CONNECTED IN SERIES WITH R, IT OPPOSES CHANGES IN LOAD CURRENT
RESULT; REDUCES THE RIPPLE CURRENT IN LOAD AND HENCE RIPPLE VOLTAGE ACROSS THE LOAD
