Magnetic Characteristics of DC Generator (Experiment No. 13) | Electrical Engineering скачать в хорошем качестве

Magnetic Characteristics of DC Generator (Experiment No. 13) | Electrical Engineering

(DC Generator Characteristics ): Magnetic Characteristics or Open Circuit Characteristic (O.C.C.): This curve shows the relation between the generated e.m.f. at no-load (E0) and the field current (If) at constant speed. It is also known as magnetic characteristic or no-load saturation curve. Its shape is practically the same for all generators whether separately or self-excited. The data for O.C.C. curve are obtained experimentally by operating the generator at no load and constant speed and recording the change in terminal voltage as the field current is varied. The O.C.C. for a d.c. generator is determined as follows: The field winding of the d.c. generator (series or shunt) is disconnected from the machine and is separately excited from an external d.c. source. The generator is run at fixed speed (i.e., normal speed). The field current (If) is increased from zero in steps and the corresponding values of generated e.m.f. (E0) read off on a voltmeter connected across the armature terminals.