Question

A factory need a drive system for a conveyer system. Voltage source available is three phase 415
Volt, 50 Hz. Electric motor that they use is DC motor.
(i) How the design of DC drive system for that system :
(ii) What the parameters should be considered?
(iii) What type of the DC motor that needed?
(iv) What kind of converters that suitable for this system?
(v) How the control system?

Answer 1

Given that the supply available is 3 phase 50 Hz 415 Volts.

The motor used is a DC motor.

(i) The design should include the type, ratings of the motor.

The converter used must be identified correctly and it has to be calculated such that it does not get overloaded.

The type of feedback must be selected to ensure the correct speed of the conveyor. Perfect gearbox must be selected.

(ii)The parameters to be considered to design the system are,

a)How much load is being driven by the motor.

b)Speed of the conveyor.

c)The capacity of the motor.

d)The overall cost of the system.

e)Working environment.

f)Maintenance flexibility

(iii)For these types of loads the starting toque required is high and thus DC series motor is best suitable.

(iv)Here the supply available is 3 phase AC source. We need a 3 phase converter which converts the AC voltage is DC voltage. This applications also can be done by using 3 phase rectifiers coupled with a DC chopper.

(v)The feedback should be taken from the conveyor by using a tacho generator. This feedback is used to control the output voltage. In the case of 3 phase converter, the firing angle of the converter is varied. In case of the combination of rectifier and chopper, the duty cycle of the chopper is varied.