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Q1— Section header —
1.1Indicate whether the following statements are TRUE or FALSE. Choose the answer and write only 'T rue or 'F alse
1.1.10\n the ANSWER BOOK.
1.1.1To gain insight into the nature of electric currents, it is necessary to consider the structure of the atom.
1.1.2In a DC circuit, power is the product of the applied voltage and the resulting current
1.1.3The strands of conductors make it imp ossible for cables to bend to a certain degree
1.1.4A positive temperature coefficient of resistance means the higher the temperature, the higher the resistance of the material
1.1.5Kirchhoff s first law states that the algebraic sum of the voltage drop in any closed circuit is equal to the algebraic sum of the applied EMF
1.1.6According to Norton s theorem, any network that has two terminals and consists of resistances, voltage sources and current sources cannot be replaced by a sing le current source
1.1.7When two magnets are placed very close to each other, like poles attract each other and unlike poles repel each other
1.1.8The two principal laws of electromagnetism are known as Faraday s laws
1.1.9Any two cond uctors eparated by an insulating material is defined as capacitor
1.1.10
1.2.1The current through each cell (4\
1.2.2The current through eac h coil (3\
1.2.3The terminal voltage of each coil (2\ 1. The field current of shunt connected generator is 4,1 A, with the initial temperature of the coil being 20
1.4.1The PD across the combination (4\
1.4.2The charge across each capacitor (2\ [30] QUESTIO N 2 DC MACHINES30
2.1Define armature reaction (2\
2.2A six pole lap wound DC generator supplies a load of 50 A at 240 V. Calculate the speed of the prime mover if the machine is shunt
2.3A short shunt, compound wound generator supplies a load with 65 A at a terminal voltage of 400 V. The series field, shunt field and armature resistances are 0 contact voltage drop if the magnitude of the generated
2.4A 500 volt DC motor has an armature resistance of 0,2 and draws a full load armature current of 100 amps. Calc ulate the starting resistance required if the overloads are set to trip at 125% of full load current
Q3— Section header —
3.1Explain the effective value of an alternating current (2\
3.2sistor and an inductance of 200 mH\ and an inductance of 100 mH\. The circuit is supplied by 200 V/50 Hz. Determine the following:
3.2.1The total current drawn by the circuit (12\
3.2.2The voltage drop across the two coils (4\
3.2.3The current through each branch of the parallel circuit (2\ [20]20
Q4— Section header —
4.1What are the TWO types of single phase transformer windings? (2\
4.2
4.2.1The peak value of the flux density in the core (4\
4.2.2The voltage induced in the secondary winding (2\
4.2.3The voltage per turn (2\ [10]10
Q5— Section header —
5.1Explain what the end plates of a motor are. (3\
5.2Name THREE types of a single phase, induction motors. (3\
5.3Discuss briefly the differences that exists between the starting and running windings of a split phase motor. (4\ [10] 808007410
6.1Beside hydro power station , what are the other TWO power stations that depend on vast quantit ies of water for their operation
6.2Give THREE reasons why coal fired power stations are built near coal mines (3\
6.3You have a scale deflection when 13,5 mA passes through it. Determine the maximum current and voltage that the instrument can be used to measure (5\ [10]10