Objective: To obtain external characteristics of a dc shunt generator
The self excited DC shunt generator is coupled to a DC motor, which acts as prime mover. Two characteristics are more important. The internal or total characteristic that gives the relation between the emf actually induced in the armature and the armature current. This is of interest mainly to the designer. The external characteristics called performance characteristics (also voltage regulating curve) which give the relation between the terminal voltage and load current. This curve lies below the internal characteristics due to armature drop. This is important in judging the suitability of a generator for a particular purpose. These characteristics can be obtained by a load test with total field resistance remaining fixed as the speed is to be kept constant.
Equipment required: All the measuring instruments associated with each experiment are industrial grade. These instruments are housed in an elegant cabinet as a package. Range of instruments and accessories (standard format)
1. 2HP Shunt machines mechanically coupled both are identical 220V 2HP 1500rpm.
2. 3-4 point DC Starter for the above
3. Suitable Loading rheostats
4. Digital tachometer
5. Suitable double tube rheostat
6. Suitable single tube rheostat
7. Suitable digital Voltmeters DC
8. Suitable digital ammeters DC.
9. Suitable DC source –Rectifier unit