A separately excited $$DC$$ shunt motor is driving a fan load whose torque is proportional to the square of the speed. When $$100$$ $$V$$ are applied to the motor, the current taken by the motor is $$8$$ $$A,$$ with the speed being $$500$$ $$rpm.$$ At what applied voltage does the speed reach $$750$$ $$rpm$$ and then what is the current drawn by the armature? Assume the armature circuit resistance to be $$1\,\,\,\Omega .$$ Neglect brush drop and mechanical losses.

Two single phase transformers $$A$$ and $$B$$ have the following parameters.
Transformer $$A$$: $$400V/200V,$$ $$10$$ $$kVA,$$ percentage resistance and percentage reactance are $$3\% $$ and $$4\% $$ respectively.
Transformer B: $$5$$ $$kVA,$$ $$400V/200V,$$ percentage resistance and percentage reactance are $$4\% $$ and $$3\% $$ respectively.
These two transformers are connected in parallel and they share a common load of $$12$$ $$kW$$ at a power factor of $$0.8$$ lag. Determine the active and reactive power delivered by transformer $$A.$$

A 4-pole lap-wound DC generator has a developed power of P watts and voltage of E volts. Two adjacent brushes of the machine are removed as they are worn out. If the machine operates with the remaining brushes, the developed voltage and power that can be obtained from the machine are

A DC shunt motor is running at 1200 rmp, when excited with 220 V DC. Neglecting the losses and saturation, the speed of the motor when connected to a 175 V DC supply is: