24-01-2013, 10:45 AM
SINGLE PHASE FULL CONTROLLED BRIDGE CONVERTER WITH R & RL LOAD
CONVERTER WITH R & RL LOAD.docx (Size: 13.74 KB / Downloads: 28)
AIM:
To obtain controlled output waveforms of a single phase fully controlled bridge
Converter with R and RL Loads.
APPARATUS:
S.No EQUIPMENT Qty
1. I-φ Transformer 1
2. I-φ fully controlled power
circuit with firing unit
3. Voltmeter(MI meter) 1
4. Voltmeter(MC meter) 1
5. Rheostat 1
6. Inductive load 1
7 CRO with (1:10) Probe 1
8. Patch cards
THEORY:
For R-Load:
A fully controlled bridge converter using four SCR’s is shown in the circuit
diagram. In the bridge circuit diagonally opposite pair of SCR’s are made to conduct and
are commutated simultaneously. During the first positive half cycle SCR’s T1 and T2 are
forward biased and they are triggered simultaneously at wt =α then the current flowing
through the path A-T1-R-T2-B. During the negative half cycle of the input SCR’s T3 and
T4 are forward biased and they are triggered at wt= (π+α) simultaneously then the current
flows through B-T3-R-T4-A. Thyristors T1,T2 and T3,T4 are triggered at same firing
angle α in each positive and negative half cycle of the input voltage respectively.
PROCEDURE:
For R-Load:
1. Connect the circuit as shown in figure.
2. Verify the connections from the lab instructor before switch on the supply.
3. Keep the rheostat position value given by the lab instructor
4. Switch ON the CRO and calibrate it with the input voltage.
5. Switch on the power circuit and firing circuit.
6. Observe the output voltage waveform in the CRO.
7. Note down the reading of α from the CRO and Vo from the voltmeter
8. Also calculate the theoretical value of output voltage from the formula and
compare it with the practical value of the output voltage, which is observed
from the voltmeter.