State TWO environmentally friendly alternatives.
Describe why it is important to look for alternatives to coal to generate electricity.
Describe why access to electricity may have educational benefits.
Describe ONE factor that may increase the cost of generating electricity.
Explain why the provision of electricity to people's homes may reduce air pollution.
Input
Process
Output
Power supply
Describe why it is important to evaluate a PAT project on completion.
Name TWO unsafe acts that can cause injuries in an electrical technology workshop.
List THREE electrical safety devices that will cut off the power supply in an emergency.
Name the type of fire extinguisher that must be used to combat electrical fires.
State TWO safety precautions that must be taken when connecting a multimeter in a circuit to measure current.
Describe why it is important to have good ventilation in a workshop.
State ONE advantage of a three-phase system over a single-phase system.
Draw a delta-connected system showing the line and phase values of current and voltage.
Calculate the current drawn at full load.
If the power factor of the load was improved to 0,98, describe what would happen to the current drawn at full load.
Name TWO factors that influence the value of the capacitive reactance of a capacitor.
Explain the term inductive reactance with reference to a coil.
Describe how an increase in the number of turns on a coil will affect the inductive reactance of the coil.
A pure resistor
A pure coil
The inductive reactance of the inductor
The capacitive reactance of the capacitor
The impedance of the circuit
The current through the circuit
Draw the phasor diagram showing the current and voltages in the circuit.
Calculate the supply current of the circuit.
Draw a fully labelled symbol of an SCR.
State TWO applications of an SCR.
Describe how an SCR is switched on using a controlled gate pulse.
Explain what determines the physical size of an SCR.
Describe how a DIAC is switched on.
Describe the function of the DIAC.
If the value of R2 is increased the brightness of the lamp will decrease. Explain how this occurs.
Describe how the voltage will be affected when the TRIAC begins to conduct.
Explain the term holding current marked IH on the characteristic curve.
Describe the term positive feedback.
Name the main disadvantage of positive feedback.
State ONE application of positive feedback in amplifiers.
Identify the labels marked 1, 2 and 3.
Name the op-amp circuit.
Draw the input and output waveforms on the same axis.
Describe the function of the reference voltage.
Draw a non-inverting amplifier circuit using an op-amp.
Explain how a non-inverting op-amp may be converted into a voltage follower.
Name ONE practical application of a transformer.
Describe the basic operation of a transformer.
Input power
Current
Voltage
The secondary line current
The primary line current
Name TWO practical applications of a PLC.
Memory
CPU
Input interfaces
Name THREE types of programming languages used in PLC programming.
Name the logic function this circuit represents.
Draw the equivalent logic symbol for this circuit.
Draw the truth table of the logic function.
Draw the ladder digram of this circuit.
Identify the control circuit represented in the ladder logic diagram.
Draw the relay control circuit that represents the ladder diagram in FIGURE 9.2.
Simplified design
Improved reliability
Compactness and standardisation
Name a digital device that may be used to count bottles in a cold drink factory.
State the TWO modes in which a three-phase stator winding may be connected.
Name THREE electrical tests that must be carried out on the stator winding of a motor before installation.
Name TWO mechanical inspections that must be carried out on a motor during maintenance.
State how the direction of rotation of a three-phase induction motor may be reversed.
State TWO advantages of three-phase motors over single-phase motors.
The current drawn from the supply
The apparent power of the motor
Explain why the casing of a three-phase motor must be earthed.
List THREE safety devices that must be included in a motor starter circuit.
Describe ONE possible cause of overheating of a three-phase induction motor.
Describe the term normally open with reference to electromagnetic relays.
Explain the function of the end shield of the motor.
Describe the purpose of using electrical switchgear in three-phase motor- control circuits.