Lab Information -- Direct Current Machine Experiments
EXPERIMENT NO. 3
SATURATION CURVE OF A D.C. GENERATOR
PURPOSE:
To study the relationship between the no-load voltage and the shunt field current of a separatelyexcited shunt generator.
APPARATUS REQUIRED:
1. One DM-100/A D.C. machine as a generator
2. One MFM-100 Multifunction machine
3. One Hampden D.C. voltmeter
4. One Hampden D.C. ammeter
5. One Hampden 0 to 150 volt power supply
6. One Hampden 120 volt A.C. power supply
PROCEDURE:
Couple the D.C. generator to the multi-function machine and make the connections shown in
Figure 3. Adjust the field rheostat to its maximum resistance, fully clockwise position. Adjust the
output of the 150 volt power supply from zero to maximum in 15 volt intervals and back from
maximum to zero in 15 volts intervals again. Record the armature voltage for about ten different
values of field current for both ascending and descending values.
NOTE:
Always adjust current in the shunt field in one direction only. Never reduce it then increase it.
Using the data obtained in the procedure, plot the ascending and descending saturation curves.
Analyze the curves, comparing it to the results that one would expect considering the theory
involved.