A dc motor is basically self-starting, it doesn't require any starting device. But in order to start the motor in a desired safe way, there is a need for an external device called 'Starter'. A dc motor can start…
In a recent article, we have seen the construction and working principle of a three-point starter. The disadvantage of a three-point starter is that due to the series connection of field winding with the no-volt coil (NVC).…
The dc motors are widely used in various applications like variable-speed drives, constant-speed drives, and many more. For selecting a type dc motor for a particular application it is very important to study the character…
In a dc machine, the given input energy will be not equal to output energy i.e., the output energy will be always less than the input energy, thereby reducing the efficiency. The whole electrical input is not available at t…
At starting when a rated voltage is applied across the stationary armature terminals of the dc motor, it draws more current comparatively greater than rated current. When such heavy currents pass through the armature windin…
Basically, there is no difference in the construction of a dc motor and dc generator. A dc motor gives a mechanical output with input as a dc supply while the dc generator gives dc electrical output with mechanical input. S…
It is seen that emf induced in the armature conductors of a dc generator is alternating in nature. The frequency of the induced emf alternates with a frequency corresponding to the product of the speed and the number of pai…
In this method, the speed control of dc motor is achieved by controlling the voltage applied across the armature terminals. It is introduced by the scientist sir Henry Ward Leonard in 1891 and named as a 'Ward Leonard …
Hopkinson's test of dc machine also known as a 'Regenerative Test'. This test is also one of the efficient ways of determining the losses and efficiency of a dc machine. The test is performed by mechanical coupl…
