C&G 2357 Unit 309 Questions With Answers

16. Which one of the following is an exposed conductive part:
a) a water pipe
b) the casing of class II equipment
c) a lightning conductor
d) the metal casing of an electric cooker

17. When measuring the current flow through a small powered d.c. component, an ammeter may be used if connected
a) to a current transformer
b) in series to the component
c) to a voltage transformer
d) in series to the components

18. Which one of the following does not help determine the voltage output of a dynamo?
a) winding the coils onto a dense iron core
b) number of turns on the coils
c) rotational speed of the coil
d) magnetic flux density

19. What type of motor depends on the number of pole-pairs and supply frequency to determine its speed?
a) synchronous motor
b) commutator motor
c) shunt wound motor
d) shaded-pole motor

20. What voltage rating are the capacitors used in a single phase capacitor-aided motor?
a) 500v
b) 250v
c) 30v
d) 400v

21. Which one of the following statements is not true of a capacitor-aided AC motor?
a) It uses a standard squirrel cage rotor design
b) the auxiliary winding has a lower impedance than the run winding
c) windings are contained within the stator
d) the auxiliary winding is permanently connected in the circuit

22. What can occur if an excessive load is placed on a synchronous motor?
a) The speed will drop slightly
b) The current drawn will trip out the MCB's or rupture the fuses in the fuseboard
c) Nothing - a synchronous motor keeps constant speed
d) The motor will stall

23. A circuit line and neutral conductor had a total resistance of 1.6 at normal operating temperatures and a load drawing a current of 10 A. The total voltage drop across the circuit would be
a) 0.8 V
b) 1.6 V
c) 8.0 V
d) 16 V

24. The most suitable solder for attaching a lug to a copper cable is called:
a) lead solder
b) plumber's metal
c) tinman's solder
d) silver solder

25. Before using an electric soldering iron:
a) the flexible cord and plug should be inspected for signs of damage
b) an inspection report should be prepared
c) the insulation resistance should be checked
d) the iron should be sent to the workshop for an overhaul

26. Which one of the following is a short circuit protection device that is not activated by heat:
a) a thermally operated circuit breaker
b) a BS 88 protection device
c) a cartridge fuse
d) a residual current device

27. The main purpose of a cable sheath is to :
a) improve its insulation
b) provide protection from mechanical damage
c) improve the flexibility of the cable
d) provide protection for outdoor situations

28. Which of the following is a method of protection against indirect contact:
a) insulation of live parts
b) earthed equipotential bonding
c) protection by barriers
d) placing out of reach

29. What part of a central heating system moves the hot water around the pipework and radiators?
a) pump
b) thermocouple
c) ductwork
d) boiler

30. What name is given to the water heater that can provide hot water 'on demand' very quickly?
a) immersion heater
b) instantaneous water heater
c) cistern type water heater
d) non-pressure water heater