Aim
To obtain DC voltage from AC input using Single phase Semi Converter with R load and RL load and also with freewheeling diode and without freewheeling diode.
Apparatus required
☞Single phase semi converter kit
☞Patch cards
☞Power card
☞CRO
Circuit Diagram
Procedure
CRO Settings
☞Time (X) Axis : 5ms/div
☞Voltage (Y) Axis : 20V/div
☞Probe : 1:10 CRO Probe is suitable one.
Initial Settings
☞Ensure the 230V Power Supply is in proper with Tester.
☞Ensure the CRO is working properly with probe checking and proper ground line axis.
Mimic Diagram
Experiment Steps
☞The connections are made as per the circuit diagram given above.
☞The R Load must be 60W bulb or 200ohm/2A Rheostat. The Load is 120mH/2A.
☞When the load is Rheostat, then it must be in maximum position.
☞Turn on the SW2 and observe the waveform across between G1&K1, G2&K2, G3&K3, and G4&K4. And ensure it is like triggering pulse given in model graph.
☞Turn ON SW1 and observe the waveform across the R load and RL Load.
☞Measure the X-axis time interval of ON time of Load Voltage and OFF Time of Load Voltage.
☞Adjust the value of Firing angle and note down the load voltage and current.
☞Repeat the step 6.
☞Repeat the experiment for different values of α and note down Vo. Note*If the connections are wrong the kit will get damage.*The load must be R and RL. Do not connect L Load alone.
Model Waveform
Pulse For SCR
Model Graph
Firing angle α variation
Observation
| S.NO | OFF Time(ms) | ON Time(ms) | Alpha(α in Degree) | Vo(Volts) |
| 1 | 4 | 6 | 72 | |
| 2 | ||||
| 3 | ||||
| 4 | ||||
| 5 |
Model Calculation
1. Total Time Period
2. The Average Output Voltage
