Consider a DC generator running at the rated speed of 2000 rpm, suddenly there is an insulator falls on the field circuit and breaks it. Then
As the field circuit gets broken there is interruption in the flux to the dc machine, and as a result the motor stops in few seconds.
If a self excited DC generator is failed to run, this refers to
Any of the reasons are valid for no build up of an emf.
The self-excited dc generator with gradual build up of residual voltage and EMF corresponds to
It responds to a positive feedback because the gain is always more than one in the linear region.
The critical resistance refers to
After taking a glance at the magnetization curve, it can be concluded that the emf will not build up if the resistance is greater than critical resistance.
If a DC shunt generator fails to start, the most primitive action would be
The first measure is to check if the field winding as properly connected with additive polarity so that the flux is aiding in nature.
Flashing is used to
It is a method to give a kick start to dc machine when its residual magnetism is vanished.
A series generator, having external characteristics which is a straight line through 0 to 50 V at 200 A is connected as a booster, between a station bus-bar and feeders of 0.5 ohm resistors. The voltage at the far end of feeder at current of 50 A is
V = voltage drop-voltage added up by boosters
= (0.3*50 – 50*50/200)
= 2.5 V
The number of parallel paths in the armature is increased by
It is increased by increasing magnetic poles which give parallel path to the magnetic circuit.
A dc series generator as armature and field connections are reversed, the generator
It happens due to non build up voltage.
____ is responsible for mechanical power output of a DC motor
Primarily it is the electrical input power which starts the motoring action.