Electrician Theory Test

Section A: 1 Mark Test Item: 1 The synchronous speed of a 4 pole induction motor connected to a 50Hz supply is (A) 200rpm (B) 750rpm (C) 1500rpm (D) 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 (A) Makes them too soft (B) Makes them too hard (C) Increases their electrical resistance (D) 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 (A Open circuited (B Short circuited (C 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 (B) The induced voltage in the armature coils as the current reverses (C) The effect of the magnetic field set up by the armature currents on the main field (D) The induced voltage in the armature coils created by interpoles 1 Mark Test Item: 5 For assembling a bearing it should be heat treated to about 80°C using (A) Oil bath (Б) Water bath (C) Soldering iron (D) Cutting torch Test Item: 6 1 Mark A capacitor is connected in parallel with an inductive load for Improvement of load factor (B) Improvement of power factor (C Improvement of correction factor (D 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? (A) Copper and nickel (B) Copper and carbon (C) Aluminium and copper (D) Carbon and silver Test Item: 8 1 Mark A 3 phase, dual voltage motor has how many leads brought out to its terminal block? (A) 6 (B) 7 (C) 8 (D) 9 Test Item: 9 1 Mark Which of the fire extinguishers is ideal for putting off electric fires (A) Class A (B) Class (C) Class C (D) Class A and C Test Item: 10 1 Mark In a workshop, gangways must be kept clear (A) To facilitate communication. (B) To allow for free movement of folk lifts. (C) To prevent accidents (D) To avoid cheating 1 Mark Test Item: 11 In a dc machine inter-poles are fitted in between the field poles in order to (A) Improve commutation (B) Increase the speed of the dc motor (C) Increase the torque of the dc machine (D) 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 (A) (B) Take a deep breath and lift (C) Lift it using gloves (D) 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 (A) Protection by MCB (B) Protection by HBC (C) A motor starter (D) A remote start/stop switches Test Item: 14 1 Mark A meter with a moving coil movement (A) Has a digital readout (B) Can be used on both ac and dc supplies (C) Has a linear scale (D) Can be used to measure power Test Item: 15 1 Mark When two different electrical components are connected in series they (A) Have the same voltage across them (B) They carry the same current through them (C) Have the same resistance (D) 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 (A) Tin and Zinc (B) Copper and Zinc (C) Zinc and Lead (D) Tin and Lead Test Item: 17 1 Mark Which of the following motors can be described as a split phase motor? (A) Shunt motor (B) Universal motor (C) Compound motor (D) Capacitor run and start motor Test Item: 18 1 Mark A temporary installation on a constructional site must be inspected and tested (A) Every three weeks (B) Every month (C) Orice a year (D) Every three months