Lesson 7 - Electricity SAQ

1.         * Are the following statements true or false? Provide reasoning for your answer.

a) Current and power are the same thing.

b) Direct current has a lower frequency than alternating current.

c) A big brewery only needs three-phase power.

d) A transformer allows you to convert power from one voltage to another.

e) Two-pole motors rotate faster than four-pole motors.

f) Power factor correction is used to decrease maximum demand.

2.         * Which applications in a brewery would you use DC power for? Justify why it is better than AC power for these applications.

3.         **  

a) Why do motors have a large initial current?

b) What is the difference between a soft starter and a variable speed drive?

c) For the following applications, recommend ways in which the maximum demand can be reduced.

i)     Five water pumps supplying water to the plant.

ii)    A large agitator that only runs at one speed.

iii)   A filter pump on a line that has a control valve on it.

4.         *

a) What is the difference between earthing and grounding?

b) Why would you not rely only on grounding?

5.         **

a) What is power factor?

b) How does power factor differ for inductive, resistive, and capacitive loads?

c) What is power factor correction and why is it important?