ELECTRICAL APPLIANCE SERVICEPERSON …...(b) Describe how you would reverse the direction of rotation in this type of motor. (c) The single-phase capacitor-start motor is connected

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23 June 2018

Time Allowed: 2 Hours

ELECTRICAL APPLIANCE SERVICEPERSON (QUALIFIED) EXAMINATION

Check the label on the back of this paper to ensure you have your paper.

INSTRUCTIONS – READ CAREFULLY

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

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 based on correctness.

Do not use correcting fluid or correcting tape.

It is recommended that the reference source for your answers be included in the space provided if a question can be answered from the Act, Regulations, Standard or Code.

However, just stating a reference only will earn no marks.

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

• Electricity (Safety) Regulations 2010 reprint dated 4 April 2016 • AS/NZS 3760: 2010

PLEASE HAND THIS PAPER TO THE SUPERVISOR BEFORE LEAVING THE ROOM

EASQ - June 2018 Page 2 of 30

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Section 1

Each part in this question is worth 2 marks. Write your answer for each part in the box provided.

Question 1 2 marks

A 230V/230V portable isolating transformer designed for personal protection is

required to be tested after a new flexible cord has been fitted.

Which of the following insulation resistance test values would permit the isolating

transformer to be returned to service?

A 10 MΩ

B 0.5 Ω

C 0.5 MΩ

D 1 Ω

Question 2 2 marks

The maximum current a flexible cord can carry safely without overheating

depends mainly on:

A The type of supply, a.c. or d.c.

B The cross-sectional area of the flexible cord conductors.

C The colours of the flexible cord conductors.

D The number of cores in the flexible cord.


Question 3 2 marks

A 230V heater comprises two elements connected in series across the supply.

If one resistance becomes open-circuited, what is the voltage across the other resistance?

A OV

B 460V

C 690V

D 230V

Question 4 2 marks

The symbol of a square within a square on a name-plate of an electrical appliance is used to indicate that the appliance is double-insulated.

Which one of the following terms on an appliance nameplate would also indicate that the appliance is double-insulated.

A Class I

B Class II

C All-insulated

D 240V

Question 5 2 marks

A switch controls two heating elements both of the same resistance. The settings

that can be selected on the switch are high, medium and low. When the high position is selected on the switch, it will connect:

A Two elements in series with the supply.

B One element in series with a suitable resistance.

C One element only across the supply.

D Two elements in parallel across the supply.

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Question 6 2 marks

When fighting a fire in live electrical equipment, which of the following fire

extinguishers should not be used?

A Water - gas expelled.

B Dry powder.

C Vaporising liquid.

D Carbon dioxide.

Question 7 2 marks

State the reason why a bayonet cap adaptor must not be used to supply a Class I electrical appliance.

A Wrong voltage rating.

B No earthing facility.

C Not mechanically strong enough.

D The cord supplying the adaptor is the wrong shape.

Question 8 2 marks

Which one of the following changes would reverse the direction of rotation of a single-phase capacitor-start motor?

A Reverse the phase and neutral supply conductor connections at

the motor terminal block.

B Reverse the connections of the centrifugal switch.

C Reverse the connections of the run winding.

D Reverse the connections of the capacitor.


Question 9 2 marks

An HRC fuse has a minimum fusing current of 30A and a 1.5 fusing factor (utilisation category). The current rating of this fuse is:

A 15A

B 20A

C 30A

D 45A

Question 10 2 marks

What is the current drawn by a small electric motor with a nameplate that reads:

Voltage 230

Phases 1

Output Power ¼ horsepower Speed 1425r.p.m.

(Assume Power Factor is 1 and Motor Efficiency is 100%).

A 2.23W

B 0.81A

C 12.23A

D 8.1A

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Section 2

Question 11 3 marks

In a single-phase capacitor-start motor:

(a) How is the start winding disconnected when the motor is up to speed?

(b) Describe how you would reverse the direction of rotation in this type of motor.

(c) The single-phase capacitor-start motor is connected to a load.

What would be the affect on the performance of the motor if the capacitor had become disconnected and the motor was switched on?

Question 12 2 marks

(a) Describe how the direction of rotation can be reversed for a universal motor.

(b)

1.

State two typical applications for a universal motor.

2.


Question 13 5 marks

The figure below shows the circuit diagram for a single-phase induction motor at

rest.

(a) What type of single-phase induction motor is being shown?

(b)

1.

Name the three components shown in the above diagram:

2.

3.

(c) Describe how you would reverse the direction of rotation in this type of motor.

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Section 3

Question 14 5 marks

You have replaced the mineral insulated metal sheathed (MIMS) element and flexible cord in a 230V, Class I, portable electric oven.

To carry out testing, a multi-function test instrument with the required functions and ranges is to be used.

(a) Refer to AS/NZS 3760 and state the test or tests using test instruments that must be carried out on the 230V, Class I, portable electric oven.

Ref:

(b) For each test stated in (14)(a) state:

• The function required to be selected on the test instrument. • The range required to be selected on the test instrument. • The permitted test result for the test. • Whether the test result is a minimum or maximum value.


Question 15 1½ marks

Refer to AS/NZS 3760 and state three visual inspections that need to be carried

out on the flexible cord and plug of a 230V, Class I, portable electric oven.

1.

2.

3.

Ref:

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Question 16 2 ½ marks

You have replaced the flexible cord and plug on a Class II electric drill.

(a) Refer to AS/NZS 3760 and state the test or tests, using test instruments, that must be carried out on the Class II electric drill.

Ref:

(b) For each test stated in (16)(a) state:

• The function required to be selected on the test instrument. • The range and test voltage required to be selected on the test

instrument. • The permitted test result for the test. • Whether the test result is a minimum or maximum value.


Question 17 1 mark

Refer to AS/NZS 3760 and describe two visual checks (inspections) that need to

be carried out on a Class II electric drill (but not the flexible cord and plug).

1.

2.

Ref:

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Section 4

Question 18 4 marks

Draw and label a circuit diagram showing an ammeter connected to measure the current supplied to a 230V, 1500W, Class II, single phase electric heater.

You must show:

● The polarity of the supply. ● The heater and element, controlled by an internal switch. ● The ammeter.

● A fuse protecting the circuit.

Question 19 2 marks

Calculate the reading on the ammeter when the heater in (18) is operating.


Question 20 2 marks

The element in the heater in question 18 is to be replaced with a 2000W element.

Calculate the resistance of the new element.

Question 21 2 marks

Calculate the power dissipated by the new element when the heater in question 18

is working and the supply voltage increases to 240V.

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Section 5

Question 22 2 marks

When replacing an HRC cartridge fuse which has blown, the replacement must have characteristics the same as the original. State the four electrical characteristics to be checked for similarity.

1.

2.

3.

4.

Question 23 2 marks

State two technical advantages that an HRC fuse has when compared to a rewireable fuse.

1.

2.

Question 24 2 marks

State two safety reasons why a blown HRC fuse cartridge must not be replaced with fuse wire of the same current rating.

1.

2.


Question 25 4 marks

(a) For which type of protective device is the term tripping factor used.

(b)

Define the term tripping factor.

(c)

Define the term current rating as it applies to an HRC fuse.

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Section 6

Question 26 3 marks

For a faulty permanently-connected electrical appliance:

(a) What does switching off the appliance mean?

(b)

What does isolating the appliance mean?

Question 27 2 marks

A 230V permanently-connected electrical appliance has been isolated and tagged. Describe two methods of ensuring that the electrical appliance remains isolated while left unattended.

(a)

(b)


Question 28 3 marks

A 230V, Class I waste disposal unit is supplied from a permanent connection unit and is controlled by a separate isolation switch that is not located adjacent to the unit.

(a)

1.

State two precautions than can be taken to secure the isolation (other than attaching a Danger Tag) because the isolating switch is not

located adjacent to the motor.

2.

(b) State the main reason a Danger Tag is attached to the isolation switch for the waste disposal unit.

Question 29 2 marks

State the two reasons why the prove test prove method of testing for isolation is used.

1.

2.

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Section 7

Question 30 4 marks

Two single phase 230V Class II, plug-in electrical appliances are each supplied by a flexible cord.

(a) Appliance 1

State one set of colour coding for the flexible cord. State the polarity for each colour.

Note: You must state the colours and polarity accurately.

(b) Appliance 2 State one set of colour coding – different from those stated for Appliance

1 - for the flexible cord. State the polarity for each colour.

Note: You must state the colours and polarity accurately.

Question 31 2 marks

An electrical appliance is being supplied from a three core flexible extension cord. The extension cord has been disconnected because it started to overheat. State the two actions, either of which could be taken to stop this situation reoccurring.

1.

2.


Question 32 1 mark

If the phrase “it is the maximum current that it is designed to carry safely” is used in respect to a flexible cord, what characteristic is being described?

Question 33 3 marks

The figure below represents the terminals of an appliance plug socket after the cover has been removed. Indicate on the figure the active (phase), neutral and earth terminals. Note: You must state the polarity accurately.

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Section 8

Question 34 2 marks

State the main reason why danger tags are used.

Question 35 4 marks

Two registered electrical appliance service persons are carrying out electrical repairs

on the same 230V, fixed-wired, industrial machine. State four precautions that must be taken when attaching danger tags to an

isolating switch of the industrial machine.

1.

2.

3.

4.


Question 36 2 marks

State the main reason why an out-of-service tag is attached to electrical equipment.

Question 37 2 marks

A voltage test is being carried out at the supply side of a single-phase isolating switch to establish if a fixed-wired Class I appliance is isolated. Between which terminals of the isolating switch would testing be carried out to clearly establish that isolation (or otherwise) has taken place.

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Section 9

Question 38 3 marks

Instrument tests are being carried out on an electrical appliance.

(a) State the main reason why a protective earthing conductor resistance test is carried out.

(b) State the main reason why a polarity test is carried out.

(c) State the main reason why an insulation resistance test is carried

out.


Question 39 4 marks

A Class I, 230V electrical appliance is used in damp conditions.

(a) Describe how the damp conditions could affect the operation of the appliance.

(b) Describe the danger that may exist for an operator who uses the appliance

without an electrical safeguard and a phase to frame fault occurs.

Question 40 1 mark

State one reason why an ohmmeter is not the correct instrument to carry out an insulation resistance test on a portable electrical appliance.

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Question 41 2 marks

Describe the internal operation of a combined thermal/magnetic MCB when an

overload occurs on the final subcircuit it protects.

For Candidate’s Use

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


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Markers Use Only Markers Use Only

Section 1 Section 5

Question 1 2 marks Question 22 2 marks




Question 5 2 marks TOTAL 10 marks

Question 6 2 marks Section 6





TOTAL 20 marks TOTAL 10 marks

Section 2 Section 7



Question 13 5 marks Question 32 1 mark

TOTAL 10 marks Question 33 3 marks

Section 3 TOTAL 10 marks


Question 15 1½ marks Question 34 2 marks

Question 16 2½ marks Question 35 4 marks

Question 17 1 mark Question 36 2 marks


Section 4 TOTAL 10 marks




Question 21 2 marks Question 40 1 mark


TOTAL 10 marks

FINAL MARK 100 marks


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Office Use Only

Result: ___________ Date: _____________ Int: ______________

Result: ______________ Date: _______________ Int: _________________

Documents

ELECTRICAL APPLIANCE SERVICEPERSON …...(b) Describe how you would reverse the direction of rotation in this type of motor. (c) The single-phase capacitor-start motor is connected