CSEC Industrial Technology Paper 2 May/June 2024 - Free CXC Past Paper with Answers

Define the term 'schematic diagram'.

Explain how a schematic diagram is used in the design of electrical circuits.

Differentiate between a 'one-line diagram' and a 'three-line diagram'.

State TWO ways in which a one-line diagram is used.

Define the term 'plot plan'.

Discuss the importance of including adjoining landmarks when developing a plot plan.

Figure 1 shows a one-line diagram.

Design a three-line diagram based on Figure 1.

State the TWO types of power transformers that are used on the electrical grid, from the generation to transmission and distribution of electricity.

Sketch and label ONE of the power transformers stated in (a) (i).

Calculate the current flowing from the voltage source of a transformer if the current flowing to the load is $10 \text{ A}$ with a transformer ratio of $63.5:1$.

State a metric unit of measurement for the following power quantities.

• True power
• Reactive power
• Apparent power

State a metric unit of measurement for the following power quantities.

• Reactive power

Identify ONE of the power quantities in (b) (i) that is used to determine power factor.

Draw and label a power triangle to represent all three power quantities.

Calculate the output true power and the corresponding reactive power of a transformer with a rated output of $200 \text{ kilo units}$ at a power factor of $0.8$.

Define the following terms in relation to electrical installation.

Domestic

Commercial

Industrial buildings

Calculate the minimum circuit breaker size for a $1 \emptyset \ 240 \text{ V}$, $8000 \text{ W}$ electrical stove.

Calculate the minimum circuit breaker size for a $1\emptyset$ 240 V, 4000 W washing machine.

Using Table 2, calculate the minimum conductor size for the loads given in (b) (i) and (ii).

TABLE 2: CURRENT RATING AND ASSOCIATED CROSS-SECTIONAL AREA FOR CONDUCTORS

CURRENT RATINGS (A)

State THREE types of fundamental dead circuit tests that are required for a new electrical installation.

Design a motor control circuit which has the following features.

• Direct online starting from a $1\emptyset$ 220 V supply
• Push buttons for starting and stopping from one station
• A pilot light to show when the starter is energized, indicating that the motor is running

Identify the TWO correct electronic symbols in the block between Stages D and E in Figure 2.

Describe the voltage that would be present for Stages A, B, C and D of the power supply shown in Figure 2. A B C D