WINCH DRIVE USING SINGLE-PHASE CONTROLLED RECTIFIER

A Separately-Excited DC Motor is driving a Winch Drum through a 1:10 speed reduction

gearing system. The diameter of cable drum is 40 cm. The motor is a 367 Frame Size whose

parameters are: 230 V, 30 hp, 1150 RPM, 108 A, 0.0963 armature resistance. The motor

armature inductance is assumed large enough such that the armature current is assumed

ripple-free. The motor is driven from a 240 V, 50 Hz sinusoidal source through a single-phase

controlled rectifier. The motor field current is assumed constant at rated value.

(1) Is the motor capable of raising the load at rated loading conditions? If not, calculate

the maximum linear velocity of the load while raising up. Then evaluate the THDF of

the supply current and the input power factor of the system. Assume constant

rotational loss.

(2) If the motor is to raise the load at rated conditions (i.e., torque and speed), what would

you suggest? In this case calculate the possible linear velocity of the system while

raising up.

(3) If the motor is to lower the load at the same raising speed without overloading,

calculate the firing angle required for this purpose, and evaluate the THDF of the

supply current and the input power factor of the system.

(4) If the motor is to hold the load at standstill, what is the value of the load current to do

so? Can you comment on such a situation?