The drop in speed from no load to full load is very high in a series motor without interpoles.
A series motor is a type of DC motor where the field winding is connected in series with the armature winding. In a series motor without interpoles, there are no additional winding or interpoles present.
The speed of a DC motor is inversely proportional to the torque load on the motor. When the motor operates at no load, there is minimal torque load on the motor, and it tends to operate at a higher speed. However, when the motor operates at full load, the torque demand increases, causing a decrease in speed.
In a series motor without interpoles, the drop in speed from no load to full load is relatively high. This is because the series motor lacks the additional flux control provided by interpoles. Interpoles are small auxiliary poles placed in the magnetic circuit of a DC motor to compensate for armature reaction and enhance the speed regulation.
Without interpoles, the armature reaction in a series motor becomes more pronounced, leading to a higher drop in speed when the motor operates at full load.
Therefore, the correct answer is C: Series motor without interpoles. The drop in speed from no load to full load is very high in a series motor without interpoles.