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Q1— Section header —
1.1The procedure below was followed during the replacement of heati ng
1.2Name the alloy that is normally used for manufacturing heating element (1\ [10] 1104126310
Q2— Section header —
2.1.1Circuit breaker
2.1.2Earth leakage (2 2\ (4\
2.2Name the components indicated in FIGURE 1 of a core balanced earth leakage relay. Write only the name of the component next to the question
2.2.6\n the ANSWER BOOK. FIGURE 1: CORE BALANCED EARTH LEAKAGE RELAY (6\ [10]10
2.2.411041263 520 (E\
Q3— Section header —
3.1Choose a description from COLUMN B that matches an item in CO LU MN A. Write only the letter (A \next to the question number (3.1.1
3.1.5\in the ANSWER BOOK. COLUMN A COLUMN B
3.1.5Tungsten halogen lamps Cold cathode neon lamps High pressure mercury
3.2FIGURE 2 shows different types of lamps as used in an electrical field. Name each type of lamp and write only the answer next to the letter
3.3State TWO main components of a compact fluorescent lamp. (2\ [10] 1104126310
Q4— Section header —
4.1The maximum current value (1\
4.2The effective value of the current
4.3The frequency
4.4The instantaneous v alue 8 milliseconds after reaching zero while increasing positively (3\ [10]10
Q5— Section header —
5.1The impedance of the circuit
5.2The total current flow
5.3The voltage drop across the resistor (3\
5.4State the nature of current flow versus voltage applied in a capacitor connected to an alternating supply. [10]10
Q6— Section header —
6.1A three phase delta connected motor draw a current of 12 A at full load from a 415 V supply at a power factor of 0,8
6.1.1The phase current flowing in the motor
6.1.2The phase voltage (1\
6.1.3The power input to the motor
6.2Make a neat labe led sketch to illustrate the delta connection of a three phase system and indic ate the line and phase voltages on your sketch.
Q7— Section header —
7.1Explain the operation principle of a transformer (2\
7.2A 300 k VA phase transformer has a star connected primary and delta connected secondary. The
7.2.1he t urns ratio of the transformer (3\
7.2.2The primary line current (3\
7.3Explain how overheating of the c ore of the transformer is avoided. (2\ [10]10
Q8— Section header —
8.1Explain, w ith reference to DC motor, the meaning of a separately excited machine. (2\
8.2Draw a neat, labe led sketch which shows the basic principles of a motor. Include the relative directions of the flux, EMF, force and motion. (5\
8.3Briefly explain the field coil connections of the following:
8.3.1Shunt motor
8.3.2Series motor
8.3.3Compound motor (3 1\ (3\ [10] 1104126310
Q9— Section header —
9.1Show, w ith a neat labelled circuit diagram, how a single phase capacitor starts
9.2Answer t he following questions with regard to a three phase wound rotor induction motor
9.2.1State how m any connection terminals are on the stator of the motor (1\
9.2.2State i which formation the rotor normally would be connected. (1\
9.2.3State w hich connection on the stator will produce a higher torque (1\
9.2.4Explain the signi ficance of interlocking (2\ [10]10
Q10— Section header —
10.1Draw a basic circuit diagram of the connections required for a voltmeter to be connected to a high voltage AC supply. (3\
10.2State the functions of the following components of measuring instruments:
10.2.1Fixed iron
10.2.2Hair springs
10.2.3Permanent magnets (3 1\ (3\
10.3Draw a neat, label ed circuit diagram to show how semi conductor diodes can be used to give three phase hal