NSW Coal Competence Board EXAMINATION FOR … · CEE1 Application of Electrical Engineering to Mining March 2014 ... working in calculations. Neatness in diagrams is essential and

(CEE1)

NSW Coal Competence Board

EXAMINATION FOR CERTIFICATE OF COMPETENCE AS Mine Electrical Engineer

(Coal Mine Health and Safety Act 2002)

6 March 2014

9.30am – 12.30pm

Application of Electrical Engineering to Mining

INSTRUCTIONS TO CANDIDATES:

It is expected that candidates will present their answers in an engineering manner making full use of diagrams, tables, and relevant circuits where applicable and showing full working in calculations. Neatness in diagrams is essential and will be considered in the allocation of marks. Questions are to be answered as a prospective manager of electrical engineering at a NSW mine.

Examination time 3 hours

Each whole question is designed for a 30 minute answer

Candidates should attempt all questions

Candidates must mark this paper with their Candidate Number only

All questions and parts are allocated their respective marking value

During the reading time candidates may use a highlighter to mark the key parts of

questions.

CEE1 Application of Electrical Engineering to Mining March 2014

Questions continue next page Page 3 of 16

Question 1 (10 marks)

The schematic below shows a transportable substation feeding a new longwall via a

borehole feeder. Outlet 2 will be used as a spare.

a) Fill in the missing values in the above drawing with what you might typically expect

to find on this substation. (2 Marks)

i. Transformer voltages

ii. Transformer MVA rating

iii. Transformer impedance

iv. NER rating

/2



b) On the time/current graph provided, draw typical protection curves for the protection

devices for MCB1 and MCB2 shown in the drawing. Clearly show which curves

represent which protection devices. (2 Marks)

/2



c) Explain what considerations you made in the positioning of the time-current curves.

(4 Marks)

/4

d) To achieve “best practice” what minimum 3-phase fault level would need to be

present at the shovel high voltage bus? (1 Mark)

/1

e) What is the maximum allowable setting for the earth continuity protection? (1 Mark)

/1




You have been appointed the Electrical Engineer at a “greenfield” coal mine construction

site. On commencement of mining-related activities you are to be appointed as the

Manager of Electrical Engineering. As a consequence you will be responsible for

developing the Mine’s Electrical Engineering Management Plan (EEMP) and the

Standards of Engineering Practice.

When considering the requirements of Clause 19 of the Coal Mine Health and Safety

Regulation 2006:

a) What Australian Standard must be complied with for installations on the surface of

the mine? (1 mark)

/1

b) What provision should be made for personnel requiring access to energy supply

authority infrastructure on the site? (2 marks)

/2



c) What provisions should be made for working on HV installations? (2 marks)

/2

d) In considering the content of Section 7 of AS3007:2013, Electrical Installations –

Surface Mines and Associated Processing Plant, what general requirements and

information would you incorporate into your equipment technical specifications with

regard to the installation of overhead power-lines? (5 marks)

/5




You have been appointed as the Manager of Electrical Engineering at a mine that has

access by two drifts.

Each drift has winders which have recently been upgraded and have been design

registered with NSW Trade & Investment, Mine Safety Operations under the provision of

the Work Health & Safety Regulations 2011(Schedule 18B Saving and transitional

provisions)

In reviewing the registration documents: a) what is your understanding of (4 marks)

i. Primary Safety Circuit ii. Secondary Safety Circuit iii. SIL rating iv. What is meant by design registered

/4



b) What is the relationship between SIL rating and reliability of a circuit (2 marks)

/2

c) List five (5) of the functions that should be incorporated in the Primary Safety circuit

(2 marks)

/2

d) Nominate the desired SIL rating of the Primary Safety Circuit and explain why this

rating would be appropriate (2 marks)

/2




Generator Installations

You are the MEE at a major new Longwall Operation. You have a large construction site

for the assembly of major production equipment.

A contractor has a requirement to construct a temporary compound for offices and

storage containers. The offices and containers will be supplied via a 250KVA Generator.

a) What five (5) specific items need to be bonded together to form the “Generating set

bonding system” as described in AS3010:2005 Electrical Installations – Generating

Sets? (2 marks)

/2

b) What specific items would you want addressed in your site layout with respect to the

electrical installation? (2 marks)

/2



c) Is there anything in particular you would require for the water tank installation or

storage containers? (2 marks)

/2

d) Draw on the attached layout drawing detailing the earthing arrangements you would

require for the entire installation and show any specific details and assumptions you

have made – see compound layout drawing next page. (4 marks)

/4



Question 5 (10 marks) Mining cables used for underground coal operations in reeling and trailing applications

are designed to be “fit for purpose” for their duty in a particularly harsh environment.

The following questions are related to this design requirement:

a) Which Australian Standard provides design criteria for Reeling and Trailing cables

used in the underground coal mining industry. (1 marks).

/1

b) With the use of the area below draw a typical cross sectional diagram of a “type 275

Cable” and identify the critical design features of the cables internal cores, insulation

and screening. (3 marks)

/3



c) Describe how and where the Type 275 cable design is utilised in the underground

mining industry, the typical size cable used and why it may be chosen over other

cable types? (3 marks)

/3

d) Explain with the use of a diagram what is meant by a “Spark Test Unit” when

referring to a licensed cable repair workshop. Show in the diagram how this device

functions and why is it used? (3 marks)

/3




Generator Installations

You are the MEE at a major new Longwall Operation. You have a large construction site

for the assembly of major production equipment.

A contractor has a requirement to construct a temporary compound for offices and

storage containers. The offices and containers will be supplied via a 250KVA Generator.

a) What five (5) specific items need to be bonded together to form the “Generating set

bonding system” as described in AS3010:2005 Electrical Installations – Generating

Sets? (2 marks)

/2

b) What specific items would you want addressed in your site layout with respect to the

electrical installation? (2 marks)

/2



c) Is there anything in particular you would require for the water tank installation or

storage containers? (2 marks)

/2

d) On the attached layout drawing (overpage), detail the earthing arrangements you

would require for the entire installation and show any specific details and

assumptions you have made. (4 marks)

/4



END OF QUESTIONS

END OF PAPER

Page 2 of 26

(CEE2)

NSW Coal Competence Board

EXAMINATION FOR CERTIFICATE OF COMPETENCE AS Mine Electrical Engineer

(Coal Mine Health and Safety Act 2002)

6 March 2014

1.30pm – 4.30pm

Legislation and standards applicable to underground coal mines

INSTRUCTIONS TO CANDIDATES:

Unless otherwise stated all references to Regulations are to the Coal Mine Health and Safety Regulation 2006

or Work Health and Safety Regulation 2011

It is expected that candidates will present their answers in an engineering manner making full use of diagrams, tables, and relevant circuits where applicable and showing full working in calculations. Neatness in diagrams is essential and will be considered in the allocation of marks. Questions are to be answered as a prospective manager of electrical engineering at a NSW mine.

Examination time 3 hours.

Each whole question is designed for a 15 minute answer.

Candidates should attempt all questions.

Candidates must mark this paper with their Candidate Number only.

All questions and parts are allocated their respective marking value.

During the reading time candidates may use a highlighter to mark the key parts of

questions.

CEE2 Legislation and standards applicable to underground coal mines March 2014

Questions continue on next page Page 3 of 26

QUESTION 1 (10 marks)

You are the Manager of Electrical Engineering (MEE) of an underground coal operation in

NSW. Incidents have occurred around Remote Controlled Mining machines which have

been identified as “Unintended Activations”, where the machine has functioned in a

manner which may place operators at risk.

a) Identify the clause in the Coal Mine Health and Safety Regulation 2006 which this

type of incident falls under, and give details of the clause wording and requirements

(2 marks)

/2

b) Australian Standard AS4240.3:2013 details the requirements for Remote Control

systems. Explain in some detail the scope of this standard. (2 marks)



/2

c) From the Standard (AS4240.3:2013) explain what is meant by:

i. Controlled Work Area

ii. No Standing Zone

iii. Residual Risk

iv. Safety Related circuit(s). (2 marks)

/2

d) Considering the requirements of this Standard (AS4240.3:2013), please detail how

you would expect each underground coal operation to deal with these requirements

and what would be the anticipated outcomes? ( 2 marks)

/2



e) Draw a diagram in the box below to identify what “Exclusion Zones” refer to for a

continuous miner in this Standard. (AS4240.3:2013) (2 marks)

/2




As the Manager of Electrical Engineering at an underground coal mine you attend daily

and weekly mine review meetings. Recent meetings have highlighted an apparent

increase in the number of cable damage incidents.

You have researched these incidents and identified the primary areas of damage has

come from:

Miner cable damage while performing breakaways, and

Shuttle car cable damage from level wind or cam spooler failures, and

Longwall Shearer Bretby cable damage, resulting from bretby sections breaking

clear of the bretby.

a) What systems and standards should be in place at your mine to deal with these types

of issues? (2 marks)

/2

b) Explain with specific examples, the types of rules you would expect to see in your

mine standards around the issues identified above? (4 marks)



/4

c) Explain how you would address these issues at your mine, considering they may not

just be “electrical issues”. Detail short-term and long-term actions? (4 marks)

/4



QUESTION 3 (10 marks) As the Qualified Electrical Engineer you are required to develop guidance to your electrical

personnel for instances when electrical personnel may be required to “test” on energised

low voltage circuits commonly found in fixed plant in surface operations.

a) What are the specific requirements listed in Work Health and Safety Legislation in this

regard. (2 marks)

/2

b) AS4836 – “Safe working on or near low voltage electrical installations and equipment”

requires a number of safety precautions to be undertaken or considered before and

during testing. List 6 of these requirements (3 marks)

/3



c) In your own words, describe what your understanding of the following terms are as

mentioned in AS4836: (3 marks)

On or Near (1 mark)

/1

Safety Observer (1 mark)

/1

Competent Person (1 mark)

/1

d) List two (2) risk control methodologies identified in the Hierarchy of Controls as listed

in AS4836. Give practical examples of how these would be applied in the

management of risks associated with live low voltage testing. (2 marks)

/2



QUESTION 4 (10 marks) You are the Manager of Electrical Engineering at an underground coal mine. An incident

has occurred where a Continuous Miner was crushing a cable against the rib line.

The investigation into the incident has identified that major burning has occurred at the

crush point on the cable, and the supply circuit breaker in the DCB has suffered flashover

damage with the district supply transformer tripping the back-up earth leakage protection.

a) On being made aware of the details of the incident, what would be your initial

concerns with respect to the operation of the electrical protection equipment?

(3 marks)

/3

b) What systems or processes need to be in place at your operation to assist in

preventing the apparent failure of the protection system in this scenario? (2 marks)

/2



c) With regard to the operation of the protection system, what would your investigation

cover? (2 marks)

/2

d) Draw a simple single line diagram as an example of how these systems may operate

with respect to your operation. (3 marks)

/3



QUESTION 5 (10 marks) AS/NZ 2081:2011 Electrical Protection devices for Mines and Quarries

a) What limitations does this standard impose on the adjustment of relay parameters?

(1 mark)

/1

b) Name four pieces of information that according to the above standard should be

included on the label of a protection device? (2 marks)

/2

c) The above Standard nominates a typical maximum EC resistance setting of 45ohms.

In determining the relay setting – what are the crucial parameters that need to be

considered? (2 marks)

/2

d) For earth continuity protection, the above Standard nominates a minimum

permissible shunt resistance of 1kOhm between a pilot core and earth. What does

this mean? (1 mark)

/1



e) Where remote start functionality is provided via a pilot circuit, what condition is

required to be prevented, and how is this achieved? (1 mark)

/1

f) The standard recommends a maximum time delay for an earth fault should not

exceed 500mSec. Under what circumstances may this value have to be exceeded?

What would be your main consideration in exceeding this value? (2 marks)

/2

g) The standard nominates a minimum insulation resistance for Earth Fault Lockout

protection. What is this value? (1 mark)

/1



QUESTION 6 (10 marks) EES-014 Small Inverters

You have been asked to develop a management plan for the use of inverters on your site.

a) In the box below, draw a typical 240V 10A single appliance inverter installation as

described in EES-014 - Technical Principles for the use of “Stand Alone”

Generators at NSW Mines (Coal and Metals) and Extractive Operations. (4

marks)

/4



b) Describe what your earthing requirements would be for this installation. (3 marks)

/3

c) What specific protection devices would you want installed on the circuit? (3 marks)

/3

d) What specific protection devices would you want installed on the circuit? (1 mark)

/1



QUESTION 7 (10 marks) Your company has just released a safety bulletin noting an increase in the number of

reported electric shocks from the use of welding equipment.

Your Operations Manager requires a report on the use of welders at your mine site and the

controls required to be in place to prevent electric shock incidents.

a) Considering Section 19(3) of the Work Health Safety Act 2011, what measures would

be appropriate in assisting to control the risk of electric shock while welding on your

site? (2 marks)

/2

b) According to AS1674.2, what specific controls should be put in place to eliminate or

minimize welding hazards in a purpose built welding bay in a surface workshop?

(4 marks)

/4



c) According to AS1674.2, what specific controls should be put in place to eliminate or

minimize electrical hazards when undertaking welding on an AFC panline on a

longwall face? (4 marks)

/4




The following are extracts from the titled Australian Standards as listed below. Fill in the

missing words from the various extracts. (1/2 Mark each)

AS3000:2007 – Wiring Rules

Clause 1.5.3.1 - Protection shall be provided against ________ __________arising from

contact with parts that are ________ in normal service (direct contact) or parts that

become live under _________ conditions (indirect contact)

Clause 1.5.4 .1 - ____________ shall be provided against __________ that may arise

from contact with parts that may become live in ___________ service.

Clause 1.8 - All electrical installations and any ______________, _____________ or

repairs to electrical installations shall, ___________ to being placed in service or use, be

_____________ as far as practicable and ______________to verify that the installation

meets the requirement of this standard as applicable.

AS4836:2011 – Safe Working on or near low voltage electrical installations and

equipment

Clause 2.1 – To _______ on or near any ___________ installations and equipment, it is

first necessary to determine whether it is ______ to do so. This can be done before

starting work by applying a ______ ____________ system at each and every work site.

The first aim shall be to ___________ the risk.

Clause 2.3.3 – Persons working on or near ______________ conductors of electrical

equipment should be aware that fault currents or up to 20 times the rated current of the

supply transformer can flow for short times during ______fault conditions

/10



QUESTION 9 (10 marks) Clause 19 (1)(c ) of the Coal Mine Health & Safety Regulation 2006 makes provisions for

the use of electrical plant only of a Gazetted type in a hazardous zone

Within the short extract of sections taken from the Gazette notice (Gazette number 10, 25

January 2008) fill in the missing words in the spaces below (10 Marks)

Schedule

1 General

1.6 Electric cables conforming to AS/NZS ____________, Electric cables Reeling and

trailing For underground coal mining purposes.

1.7 Electric cables conforming to AS/NZS ____________ Electric cables Underground

coal mines – Other than reeling and trailing.

1.8 Any electric cable determined as suitable by the ____________ (in consultation with

the manager of electrical engineering for the coal operation), that is used solely as part of

an ____________ ____________circuit or is integral to a ____________

1.9 In a hazardous zone where the flammable gas concentration is greater than

____________ by volume in the general body of air, only the following types of electrical

plant.

2 Valid certificate of conformity.

The certificate of conformity:

2.1 for ____________.____________ (mines susceptible to firedamp) as defined in

section 4 of AS/NZS 60079.0:2005 Electrical apparatus for explosive gas atmospheres,

Part 0: General requirements, or, for plant that is intrinsically safe, Group II associated

apparatus, as defined in AS/NZS 60079.0:2005 Electrical apparatus for explosive gas

atmospheres, Part 0: General requirements and,

2.2 must be an ____________ ____________ certificate of conformity, or, an

____________ ____________ certificate of conformity, or, an ____________

____________certificate of conformity.

/10



QUESTION 10 (10 marks) Increased Safety (Exe) is a form of Explosion Protection technique increasingly used in

underground coal mines.

a) In your own words, what is the definition of “Increased Safety”? (1 mark)

/1

b) List at least four (4) concepts used in the design of Exe equipment (2 marks)

/2

c) Give examples of typical Increased Safety equipment currently used in the industry

(1 mark)

/1



d) When an inspection of an Exe lighting box enclosure on a Longwall face was carried

out, it was identified that the external cable glands entering the enclosure were

standard off the shelf PVC glands. Are these allowed for this type of enclosure?

Justify your answer. (3 marks)

/3

e) On inspecting an Exe conveyor motor operating in a hazardous zone it is apparent

that, at some previous time, the motor terminal block has been removed (for reasons

unknown), and the motor leads have been directly bolted to the motor supply cable

conductors. These connections appear to have been taped up utilising an

appropriately rated insulation tape. Is this permitted? Justify your answer. (3 marks)

/3



QUESTION 11 (10 marks) As a Manager of Electrical Engineering you are expected to have a sound understanding

of Acts, Regulations Standards, Gazette notices, Code of Practices and Guidelines.

a) List what Acts and Regulations govern the use of electricity in NSW Coal mines.

(2 marks)

/2

b) With the aid of any sketches describe your understanding of the relationship of Acts,

Regulations Standards, Gazette notices, Code of Practices and Guidelines. The next

page has been left blank for any sketches. (4 marks)

/4





c) In the event of an electrical notifiable incident at your mine site. (4 marks)

i. Who is responsible to make any notifications

ii. Whom is to be notified

iii. What time frames are notifiables to be report

/4




Intrinsic Safety Concepts

AS60079:11 – Equipment protection by Intrinsic Safety

AS60079:25 – Assessment of simple IS systems.

a) On a Certificate of Conformity for an IS device, what would the suffix “X” signify in the

Certificate Number? (1 mark)

/1

b) Where a Certificate of Conformity for an IS device has Conditions of Use, who is

responsible for ensuring the conditions of use are adhered to? (1 mark)

/1

c) Can IS equipment certified for use in a Group II atmosphere be used in a gas

drainage plant located on the surface of an underground coal mine? (1 mark)

/1

d) Further to (c) what would be one issue associated with using Group II equipment in

an installation at a coal mine? (1 mark)

/1


Page 26 of 26

e) In the box below, draw a sample block diagram for the following simple IS system:

(6 marks):

An IS air velocity meter is located in a hazardous area connected to a PLC analogue

input in a safe area via a IS transmitter. Include all key parameters utilising typical

expected values. In your diagram, the relationship between all input and output

parameters (eg Um; Uo; Ii; Io; Co; Ci; Lo; Lr) should demonstrate that the circuit is

compliant.

/6

END OF QUESTIONS

END OF PAPER

Documents

NSW Coal Competence Board EXAMINATION FOR … · CEE1 Application of Electrical Engineering to Mining March 2014 ... working in calculations. Neatness in diagrams is essential and