Electrical Industry Electrician Class 2 Theory Test PDF (Zimbabwe)

# Ministry of Higher & Tertiary Education ## Industrial Training and Trade Testing Department ### ZIMBABWE ### ELECTRICAL INDUSTRY ### ELECTRICIAN #### Class: 2 #### Theory Test ### Instructions to candidate: - Write your identity number on all loose the answer sheets provided - Check if all your...

# Ministry of Higher & Tertiary Education ## Industrial Training and Trade Testing Department ### ZIMBABWE ### ELECTRICAL INDUSTRY ### ELECTRICIAN #### Class: 2 #### Theory Test ### Instructions to candidate: - Write your identity number on all loose the answer sheets provided - Check if all your test papers are complete - Attempt all questions - On multiple choice questions only one answer is correct. The marking has to be done carefully and only in ink - Do not put any marks on the question papers - Submit the complete question paper together with your answer sheet. Failure to submit question paper will lead to disqualification for 3 years. - Candidates are allowed to use calculators - Show working on all calculation questions ### Time: 150 Minutes ### Number of questions: 35 ### Type of question: 20 Multiple choice, 10 Short Answer & 5 Essay type ## Section A: ### Test Item: 1 1 Mark The synchronous speed of a 4 pole induction motor connected to a 50Hz supply is - 200rpm - 750rpm - 1500rpm - 3000rpm ### Test Item: 2 1 Mark Copper and aluminium are used as electrical conductors in a virtually pure state since the addition of alloying materials - Makes them too soft - Makes them too hard - Increases their electrical resistance - Makes it more difficult to machine them or draw them into a wire ### Test Item: 3 1 Mark Before an ammeter can be removed from the secondary terminals of a current transformer connected to a load, the transformer terminals must be - Open circuited - Short circuited - Connected to the primary winding - Connected to earth ### Test Item: 4 1 Mark Armature reaction in a dc machine is - The torque produced on the field pole by the rotating armature - The induced voltage in the armature coils as the current reverses - The effect of the magnetic field set up by the armature currents on the main field - The induced voltage in the armature coils created by interpoles ### Test Item: 5 1 Mark For assembling a bearing it should be heat treated to about 80°C using - Oil bath - Water bath - Soldering iron - Cutting torch ### Test Item: 6 1 Mark A capacitor is connected in parallel with an inductive load for - Improvement of load factor - Improvement of power factor - Improvement of correction factor - Improvement of volt factor ### Test Item: 7 1 Mark Which of the two elements are commonly used in the manufacture of carbon brushes that are used on electrical machines? - Copper and nickel - Copper and carbon - Aluminium and copper - Carbon and silver ### Test Item: 8 1 Mark A 3 phase, dual voltage motor has how many leads brought out to its terminal block? - 6 - 7 - 8 - 9 ### Test Item: 9 1 Mark Which of the fire extinguishers is ideal for putting off electric fires - Class A - Class B - Class C - Class A and C ### Test Item: 10 1 Mark In a workshop, gangways must be kept clear - To facilitate communication - To allow for free movement of folk lifts - To prevent accidents - To avoid cheating ### Test Item: 11 1 Mark In a dc machine inter-poles are fitted in between the field poles in order to - Improve commutation - Increase the speed of the dc motor - Increase the torque of the dc machine - To reduce the current when starting the machine ### Test Item: 12 1 Mark The right way to lift a load is - Bend down, take a firm grip and lift - Take a deep breath and lift - Lift it using gloves - Take a firm grip, secure a good footing, place fleet at comfortable distance apart, bend the knees, keep back straight and lift with leg muscles ### Test Item: 13 1 Mark All electric motors with a rating above 0.37KW must be supplied with - Protection by MCB - Protection by HBC - A motor starter - A remote start/stop switches ### Test Item: 14 1 Mark A meter with a moving coil movement - Has a digital readout - Can be used on both ac and dc supplies - Has a linear scale - Can be used to measure power ### Test Item: 15 1 Mark When two different electrical components are connected in series they - Have the same voltage across them - They carry the same current through them - Have the same resistance - Have the same load ratings even if they have different resistance values ### Test Item: 16 1 Mark Soft solder used for electrical joints is an alloy of - Tin and Zinc - Copper and Zinc - Zinc and Lead - Tin and Lead ### Test Item: 17 1 Mark Which of the following motors can be described as a split phase motor? - Shunt motor - Universal motor - Compound motor - Capacitor run and start motor ### Test Item: 18 1 Mark A temporary installation on a constructional site must be inspected and tested - Every three weeks - Every month - Once a year - Every three months ### Test Item: 19 1 Mark A tong tester instrument can also be correctly called - A dynamometer wattmeter - An insulation resistance tester - An earth loop tester - A clip on ammeter ### Test Item: 20 1 Mark A transformer core is laminated - To reduce hysteresis loss - To reduce eddy current loss - To make the core lighter than if made from solid material - To facilitate cooling of the core ## Section B: ### Test Item: 1 3 Marks State three advantages of a nickel cadmium cell. ### Test Item: 2 5 Marks a) State ohms law b) Calculate the current flowing in a 50Ω resistor and the power it dissipates when a voltage of a100V is applied to its ends. ### Test Item: 3 2 Marks What is power factor? ### Test Item: 4 2 Marks Name the substance used to absorb moisture in a transformer unit. ### Test Item: 5 2 Marks What is the effect of having an inductive load of power factor 80% or 0.8 on an installation? ### Test Item: 6 4 Marks Describe briefly the following parts of a DC motor - Armature - Commutator ### Test Item: 7 4 Marks What is the difference between ampere- hour efficiency and watt-hour efficiency ### Test Item: 8 2 Marks What is the purpose of a fuse? ### Test Item: 9 5 Marks Explain how the arcing horns afford lighting protection to a transformer. 5 marks ### Test Item: 10 3 Marks What is discrimination? ## Section C: ### Test Item: 1 10 Marks Define the following terms - **Synchronous speed**: 2 marks - **Slip**: 2 marks - **Rotor speed**: 2 marks - Calculate the synchronous speed of a 6 pole machine connected to a 60Hz supply: 2 marks - What is the slip of the machine above has a rotor speed of 1000rpm?: 2 marks ### Test Item: 2 10 Marks Explain how the following are used to afford lightning protection to a transformer: - Lightning arrestors: 5 marks - Arcing horns: 5 marks ### Test Item: 3 10 Marks State what the following instruments are used to measure and show how they are connected. - Ammeter - Voltmeter - Ohmmeter - Megger - Tong tester