VTU NOTES QUESTION PAPERS NEWS RESULTS FORUMS TESTING OF HALF WAVE, FULL WAVE AND BRIDGE RECTIFIERS WITH AND WITHOUT CAPACITOR

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James Holland
5 years ago
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1 TESTING OF HALF WAVE, FULL WAVE AND BRIDGE RECTIFIERS WITH AND WITHOUT CAPACITOR Aim: To determine the ripple factor, efficiency and regulation of the half wave, full wave and bridge rectifier circuits with and without capacitor. Apparatus: Diode-1N4007, load resistor -1kΩ & 1/2W, capacitor 100µF, transformer - 15V-0-15V, ammeter 0-25mA (MI) and 0-25mA (MC), voltmeter 0-25V. Theory: Rectification is the process of converting the alternating quantity (AC) to the unidirectional quantity (DC with pulsation). The transformer is used to step down the voltage from 230V to the desired level. Then, the diode is responsible for the conversion of ac available at the secondary of the transformer into DC with pulsation. Hence, the diode used for this application is also referred as rectifier. The capacitor connected across the load (resistor) is behaving as a filter. Filter is responsible to smooth the pulsating DC into pure DC. Half wave rectifier is one which converts the ac into pulsating dc during one half of the cycle. It has poor ripple factor, conversion efficiency and voltage regulation. Full wave rectifier is one which converts the ac into pulsating dc during both cycles. For this process two diodes and centre tapped transformer are required. It has better ripple factor, conversion efficiency and voltage regulation compare to the half wave rectifier. The centre tapped transformer is costly compare to without centre tap. This can be overcome by using 4 diodes in a bridge. The bridge rectifier has same ripple factor and conversion efficiency as that of full wave rectifier, but better utilization factor. 1

2 Procedure: Without Capacitor: 1. Connections are made as shown in the figure for half wave rectifier circuit. 2. Measure the voltage across the terminals when the resistor is open circuited (No load). 3. Connect the load resistor across the output terminals and note, the voltmeter reading and ammeter readings (I rms and I DC ). 4. Repeat the above procedure for full wave rectifier and bridge rectifier. With Capacitor: 1. Connections are made as shown in the figure for half wave rectifier circuit with capacitor. 2. Measure the voltage across the terminals when the resistor is open circuited (No load) but capacitor is connected. 3. Connect the load resistor across the output terminals and note, the voltmeter reading and ammeter readings (I rms and I DC ). 4. Repeat the above procedure for full wave rectifier and bridge rectifier with capacitor. 2

3 CIRCUIT-Half Wave Rectifier Fig.1 CIRCUIT-Half Wave Rectifier with capacitor Fig.2 CIRCUIT-Full Wave Rectifier 3

4 Fig. 3 CIRCUIT-Full Wave Rectifier with filtor Fig.4 CIRCUIT-Bridge Rectifier Fig.5 CIRCUIT-Bridge Rectifier with capacito Fig.6 4

5 Tabulation: Position of the switch Open Closed I DC I RMS V M V DC Calculations: Without Capacitor: γ = [(I RMS /I DC ) 2-1] 2 %η = (P DC /P AC )x100 P DC =I 2 DC R L P AC =I 2 RMS R L %VR = (V NL -V L /V L )x100 With capacitors: γ = 1/(2(3) 1/2 R L fc) %η = (P DC /P AC )x100 P DC =I DC 2 R L P AC =I RMS 2 R L %VR = I DC /2fC 5

Examples to Power Supply

Examples to Power Supply Example-1: A center-tapped full-wave rectifier connected to a transformer whose each secondary coil has a r.m.s. voltage of 1 V. Assume the internal resistances of the diode and