Electrical Appliance Serviceperson Examination - … · You have 10 minutes to read this paper but...

EAS 1080

Candidate Code No.

For Board Use Only

Result Date Int

Result Date Int

ELECTRICAL APPLIANCE SERVICEPERSON EXAMINATION

10 September 2016 QUESTION AND ANSWER BOOKLET

Time Allowed: 2 Hours INSTRUCTIONS – READ CAREFULLY

You have 10 minutes to read this paper but do not start writing until instructed to do so by the supervisor.

Write your Candidate Code Number in the box provided above. Your name must NOT appear anywhere in this paper.

Answer all questions.

The pass mark for this examination is 60 marks.

Use a pen for written answers. Do not use a pencil or a red pen.

Drawing instruments and pencils may be used when diagrams are required. Marks are allocated on the basis of correctness.

Do not use correcting fluid or correcting tape.

If a question can be answered from the Act, Regulations, Standard or Code of Practice it is recommended that the relevant clause or regulation number be stated in the reference space provided. For calculation questions all workings, including formulae, must be shown to gain full marks.

For calculation questions all workings, including formulae, must be shown to gain full marks.

You will need to use the following documents in this examination:

● Electricity (Safety) Regulations 2010 reprint dated 1 August 2014 or the Electricity (Safety) Regulations 2010 reprint dated 4 April 2016.

● AS/NZS 3760:2010

PLEASE HAND THIS PAPER TO THE SUPERVISOR BEFORE LEAVING THE ROOM

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EAS 1080 QUESTIONS – 10 SEPTEMBER 2016

2

Question 1 Each part in this question is worth 2 marks. Write your answer for each part in the box provided (a) An earth continuity test has been carried out on a repaired Class I electrical

appliance. A protective earthing conductor resistance that will permit the electrical

appliance to be returned to service is: 1. 1 MΩ 2. 1.25Ω

3. 1.5Ω 4. 0.58Ω (b) Under which of the following circuit conditions is a PRCD specifically

designed to operate? 1. An earth leakage 2. An overload of short duration

3. A high motor starting current 4. A short circuit (c) At 18.5c per unit, what will be the cost of the electrical energy consumed in

6 hours by a heater which draws 10A from the 230V supply? 1. $3.00 2. $2.55

3. $2.00 4. $4.60

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3

Question 1 continued (d) A three-heat switch controlling two heating elements is connecting two

elements in series with the supply. The three-heat switch is in which position.

1. Medium 2. High 3. Low

4. None of the above (e) The main reason for carrying out an earth continuity test on a Class I

electrical appliance is to: 1. Verify that the resistance does not exceed 1 Ω. 2. Verify that the appliance will operate at 230V.

3. Verify that the resistance does not exceed 1 MΩ 4. Verify that the appliance will develop the full power output (f) Which of the following voltage ranges defines standard low voltage in a

multiple-phase MEN system in accordance with the Electricity (Safety) Regulations 2010?

1. 230 volts AC between phases 2. 230 volts AC between neutral an earth

3. 400 volts AC between phase and neutral 4. 230 volts AC between phase and neutral

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4

Question 1 continued (g) An electric heater has an output of 2 kW when operating at 230V. What is the drop in power output if the operating voltage drops 5%? 1. 5% 2. 10%

3. 3% 4. 15% (h) State the power output of an electric motor with a nameplate that reads: Voltage 230 Phases 1 Horsepower 0.5 Speed 1425 r.p.m. 1. 373 W

2. 415 W 3. 460 W 4. 500 W (i) An HRC fuse with a utilisation category (fusing factor) of 1.5 has a current

rating of 32A. The fusing current of the fuse is: 1. 40A 2. 16A

3. 32A 4. 48A

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5

Question 1 continued (j) The flexible cord of a 230V, double-insulated electric clock is to be replaced. The most appropriate type of flexible cord to use would be: 1. Twisted conductor three-core unsheathed 2. Light duty two-core tough plastic sheathed

3. Light duty three-core tough plastic sheathed 4. Two single core conductors, unsheathed

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6

Question 2 (a) State TWO safety reasons why a bayonet cap adaptor must not be used to

supply a 230V, Class I, 2kW, plug-in heater. (2 marks)

(1) ________________________________________________________

________________________________________________________

(2) ________________________________________________________

________________________________________________________ (b) Describe THREE technical qualities that an insulating material must

possess to be suitable for use as insulation in a flexible cord. (3 marks)

(1) ________________________________________________________

________________________________________________________

(2) ________________________________________________________

________________________________________________________

(3) ________________________________________________________

________________________________________________________ (c) A three-core flexible cord is to be fitted to a 230V, Class I electrical

appliance. State ONE reason why the protective earth conductor should be longer

than the phase and neutral conductors when being terminated. (2 marks)

____________________________________________________________ ____________________________________________________________

____________________________________________________________ ____________________________________________________________

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7

Question 2 continued (d) Describe how an energy controller (Simmerstat) controls a load.

(1 mark) ____________________________________________________________ ____________________________________________________________

____________________________________________________________ (e) Describe how a thermostat controls a load.

(2 marks) ____________________________________________________________ ____________________________________________________________

____________________________________________________________ ____________________________________________________________

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8

Question 3 (a) A new flexible cord is to be fitted to a Class I electrical appliance. (i) State the minimum number of conductors required for the flexible

cord. (1 mark)

________________________________________________________ (ii) Refer to AS/NZS 3760 and state the colour coding and polarity of the

conductors of the flexible cord. (3 marks)

________________________________________________________

________________________________________________________

________________________________________________________

Ref: ……………………………………….

(b) A new flexible cord is to be fitted to a Class II electrical appliance.

(i) State the minimum number of cores required for the flexible cord. (1 mark)

________________________________________________________ (ii) Refer to AS/NZS 3760 and state the colour coding and polarity of the

conductors of the flexible cord. (2 marks)

________________________________________________________

________________________________________________________

________________________________________________________

Ref: ……………………………………….

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9

Question 3 continued (c) A 230V, 25 metre three core flexible extension cord is used to supply a 2

kW heater. State ONE reason why the heater does not produce the full 2 kW output.

(1 mark) ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ (d) A 230V, 25 metre three core flexible extension cord is used to supply a 2

kW heater. State ONE reason why the flexible cord overheats.

(1 mark) ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ (e) Define the term current rating as it applies to a flexible cord.

(1 mark) ____________________________________________________________ ____________________________________________________________ ____________________________________________________________

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10

Question 4 Introduction A 230V, 600W, Class I washing machine was plugged into a live socket outlet and turned on. The machine was faulty and the 20A HRC fuse with a 1.5 utilisation category (fusing factor) protecting the socket outlet operated (blew). Tests on the washing machine showed: ● A protective earthing conductor resistance was 0.62 Ω. ● A phase to frame fault of 1.1 Ω. Use the information in the introduction to this question to answer parts 4(a), 4(b) and 4(c). (a) Calculate the total current flowing when the washing machine was

operating. (5½ marks)

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11

Question 4 continued (b) Use calculations to show why the 20A HRC fuse operated.

(2 marks) (c) Use calculations to show the voltage that appeared on the frame of the

washing machine when it was turned on. (2½ marks)

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12

Question 5 (a) HRC fuses are commonly used for protection of final subcircuits. (i) Define the term current rating as it applied to an HRC fuse.

(2 marks)

________________________________________________________

________________________________________________________ ________________________________________________________ ________________________________________________________ (ii) When replacing an HRC cartridge fuse, the replacement must have

characteristics the same as the original. State the FOUR electrical characteristics to be checked for similarity.

(2 marks) (1) ____________________________________________________

(2) ____________________________________________________

(3) ____________________________________________________

(4) ____________________________________________________ (iii) State TWO technical electrical advantages that an HRC fuse has

when compared to a rewireable fuse. (2 marks)

(1) ____________________________________________________

____________________________________________________

____________________________________________________

(2) ____________________________________________________

____________________________________________________

____________________________________________________

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13

Question 5 continued (iv) State TWO safety reasons why a blown HRC fuse must not be

replaced with fuse wire of the same current rating. (2 marks)

(1) ____________________________________________________

____________________________________________________

____________________________________________________

(2) ____________________________________________________

____________________________________________________

____________________________________________________ (b) A RCD is live. The test button is pushed, but the RCD does not trip. State TWO conditions, any one of which would prevent the RCD from

tripping. (2 marks)

(1) ________________________________________________________

________________________________________________________ (2) ________________________________________________________

________________________________________________________

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14

Question 6 Introduction The figure below is a 230V class I oven with three compartments. There is one element in each compartment. ● Element 1 is 26.45 Ω ● Element 2 is 52.9 Ω ● Element 3 is 105.8 Ω

Use the information in the introduction to this question to answer parts 6(a), 6(b) and 6(c).

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E

3 2 1

N

Control Switch Fuse

P


15

Question 6 continued (a) Calculate the total power consumed by the oven when all switches are in

the on position. (4 marks)

(b) Calculate the total current drawn by the oven when all switches are in the

on position. (2 marks)

(c) Calculate the current drawn by the oven when only element 1 and element

3 are operating. (4 marks)

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16

Question 7 (a) In a single-phase capacitor-start motor: (i) How is the start winding disconnected when the motor is up to speed?

(1 mark) ________________________________________________________ (ii) Describe how you would reverse the direction of rotation in this type

of motor. (1 mark)

________________________________________________________ ________________________________________________________ ________________________________________________________ (iii) What would be the effect on the performance of this single-phase

capacitor-start motor if the capacitor had become disconnected and the motor was switched on whilst connected to a load?

(1 mark) ________________________________________________________ (b) (i) Describe how the direction of rotation can be reversed for a universal

motor (1 mark)

________________________________________________________ ________________________________________________________ ________________________________________________________ (ii) State TWO typical applications for a universal motor

(1 mark) (1) ____________________________________________________ (2) ____________________________________________________

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17

Question 7 continued (c) The figure below shows the circuit diagram for a single-phase induction

motor at rest. (i) What type of single-phase induction motor is being shown?

(1 mark) ________________________________________________________ (ii) Name the components shown in the figure:

(3 marks) A ____________________________________________________

B ____________________________________________________

C ____________________________________________________ (iii) Describe how you would reverse the direction of rotation in this type

of motor. (1 mark)

________________________________________________________ ________________________________________________________ ________________________________________________________

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Phase

Neutral

A

B

C


18

Question 8 Introduction In an office, a 16A MCB protects a final subcircuit consisting of three socket outlets supplying various 230V plug-in electrical appliances. The appliances were operating normally until the MCB tripped. When the MCB was reset, it tripped again. A faulty appliance is causing the MCB to trip. Use the information in the introduction to this question to answer parts 8(a) and 8(b). (a) TWO types of fault in an electrical appliance that could cause the MCB to

trip. State those TWO faults.

(2 marks) (1) ________________________________________________________ ________________________________________________________

(2) ________________________________________________________ ________________________________________________________

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19

Question 8 continued (b) For each of the two faults stated in (a) describe how an electrical appliance

is tested to locate the fault. Include: ● The test instrument used. ● The test result if the fault is in an appliance. Test 1

(4 marks)

____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ Test 2

(4 marks)

____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ ____________________________________________________________

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20

Question 9 (a) You have repaired a 230V, Class I, plug-in electrical appliance and are

carrying out the instrument tests required by AS/NZS 3760. An ohmmeter is being used to carry out the first test. (i) What type of test is being carried out with the ohmmeter?

(1 mark) ________________________________________________________

(ii) Explain how the test stated in (a)(i) is carried out.

(2 marks) ________________________________________________________

________________________________________________________

________________________________________________________

________________________________________________________ (iii) (1) What is the permitted resistance for the test stated in (a)(i)?

(1 mark) ____________________________________________________ (2) Is this resistance a minimum or maximum value?

(1 mark) ____________________________________________________

(iv) State ONE reason for carrying out the test stated in (a)(i) (1 mark)

________________________________________________________

________________________________________________________

________________________________________________________

________________________________________________________

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21

Question 9 continued (b) The second test to be carried out on the 230V, Class I, plug-in electrical is

an insulation resistance test. (i) What type of test instrument is used for an insulation resistance test?

(1 mark)

________________________________________________________ (ii) What test voltage is applied?

(1 mark)

________________________________________________________ (c) Explain why an ohmmeter cannot be used to carry out an insulation

resistance test on a portable electrical appliance. (2 marks)

____________________________________________________________

____________________________________________________________

____________________________________________________________

____________________________________________________________

____________________________________________________________


22

For Candidate’s Use For Examiner’s Use Only Questions

Answered Marks

In the box, write the number of EXTRA sheets you have used. Write NIL if you have not used any

1

2

3

4

5

6

7

8

9

TOTAL MARKS

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