Lab manual_ DCM&Tr-2025
Experiment Name:: Plot the O.C.C. of a D.C. generator & find the critical resistance
Aim of the Experiment:
To Plot the Open Circuit Characteristics of DC generator
To Find the Critical Resistance(Rc) of Shunt Generator
Theory:
Circuit Diagram
Specification:
Required instruments for this experiment:
Sl. No | Instruments / Tools Used | Type(AC/DC) | Quantity | Range |
1 | Ammeter | |||
2 | Voltmeter | |||
3 | Ammeter | |||
4 | Voltmeter | |||
5 | Tachometer |
Name Plate Details:
DC Generator:
Sl.No | Item | Value | Item | value |
1 | HP/KW | 2 | RPM | 1500 |
2 | Armature Voltage | 220 | Field Volt | 220 |
3 | ARM.AMPS | 8 | Field Current | 0.8 |
4 | Front Brg | Rear Brg | 6305 | |
5 | RCC:ISS | 4722 | T,rise | 45 °C |
6 | Ins. Class | B | Year | |
DC Motor:
Sl.No | Item | Value | Item | value |
1 | HP/KW | 3 | RPM | 1500 |
2 | Armature Voltage | 220 | Field Volt | 220 |
3 | ARM.AMPS | 12 | Field Current | 0.8 |
4 | Front Brg | 6206 | Rear Brg | 6305 |
5 | RCC:ISS | 4722 | T,rise | 45 °C |
6 | Ins. Class | B | Year | 2021 |
Procedure to operate the experiment
Connect the circuit as guided by the Lab in- charge.
For generator part- First complete the armature circuit but keep open the Field circuit to measure the residual voltage.
As, at zero field current the generator supplies residual voltage.
Then, complete the generator field circuit and measure the generated voltage for different field current.
Procedure to operate the experiment
1. ON the MCB to supply the power to the panel. Observe the indicator light and voltmeter showing reading.
2. Start to operate the 3 point DC starter slowly and move it towards the last stud.Hold a moment and leave it here.
3. Measure the residual generated voltage at zero field current as the field is open.
4. Stop the MCB.
5. Complete the generator field circuit.
6. ON the MCB and operate the starter as before .
7. Measure the generator generated voltage at different field current.
8. You have reached your result. Complete the experiment
9. OFF the MCB.
Precautions for this experiment::
1. Don’t touch any live connection.
2. Use the tools which are well insulated.
3. Use proper shoes and hand gloves.
4. Measure the Residual voltage of the generator keeping open the field circuit of the generator.
5. Stop the MCB and complete the field circuit and measure the generated voltage at different field current.
6. Don’t supply the field current beyond its rated value.
7. If possible use constant DC voltage to operate the DC motor which is a prime mover of this experiment.
Data Table:
Sl. No | Field Current | Genereted Voltage |
1 | 0 | 25 |
2 | 0.1 | 76 |
3 | 0.25 | 190 |
4 | 0.375 | 230 |
5 | 0.5 | 260 |
6 |
:
You draw your own graph.
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