(CEE 1) NSW Coal Competence Board
EXAMINATION FOR CERTIFICATE OF COMPETENCE AS Mine Electrical Engineer (Coal Mine Health and Safety Act 2002)
9.30am – 12.30pm, 17th August 2011
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. Clearly state any assumptions you make in
answering the questions. 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 each answer page with their Candidate Examination
Number.
• All questions are allocated with their respective marking value.
• Parts of the answers for questions 2 and 3 are to be provided on the
‘Boutique surface reclaim tunnel’ layout and the ‘Boutique mine 107 panel’
drawings. Both of these A3-size sheets are to be noted with your candidate
number clearly visible where indicated and handed in with your answer book.
Page 1 of 7
Application of Electrical Engineering to Mining
QUESTION 1 (10 marks)
You have just been appointed as the Manager of Electrical Engineering at an underground
mine that has, on average, 6-9 m3 in-seam gas content. The mine is ventilation
constrained and you have identified that during the previous 12 months the mine has
reported over 450 gas trips as notifiable incidents to the regulator.
The mine has been operating for 10 years with a stable workforce; however you have
been advised during your handover that five of your 23 electricians have resigned and will
all leave within one month.
As part of a review you have conducted of the electrical engineering management plan
(EEMP) and standards of engineering practice (SEP), you have identified that there is no
formal electrical induction management plan for the mine. All the applications you have
reviewed are ‘clean skin’ electricians who all have a NSW Qualified Supervisors electrician
license.
a)
Draft the scope of an electrical appointment ‘management plan’. (6 marks)
b)
List the competencies you would include within the management plan. (4 marks)
Page 2 of 7
Application of Electrical Engineering to Mining
QUESTION 2 (10 marks)
You are the Manager of Electrical Engineering at an underground mine that is
undergoing a major upgrade to the surface Coal Handling and Preparation Plant
(CHPP) for which you have responsibility. The upgrade will involve the construction
of a reclaim tunnel that will have three valve entries fitted with hydraulically controlled
gates and power pack adjacent to the gates. The power pack is installed in the coal
valve chamber which is 3 metres above the conveyor belt and out of the ventilation
flow.
You have been asked by the mine operator to provide your electrical requirements to
the designer for the tunnel. State any other requirements you have for the designer to
include or consider within the design.
a) What are the requirements you would specify to be carried out as part of the design
stages (3 marks)
b) On the drawing ‘Boutique surface reclaim tunnel’, show the locations and types of
monitoring equipment you will require to be installed within the tunnel and any other
items of plant you require within the tunnel. (5 marks)
c) For any monitoring equipment you have nominated, what explosion protection
group classification is acceptable for use. (1 mark)
d) Who would be permitted to maintain the type of equipment selected in this area? (1
mark)
Page 3 of 7
Application of Electrical Engineering to Mining
QUESTION 3 (10 marks)
Your mine is experiencing difficulties in maintaining CH4 levels within the requirements of
the Coal Mine Health and Safety Regulation 2006 at the commencement of the hazardous
zone for longwall development sections. The ventilation officer has advised the Manager of
Mining Engineering that all possible ventilation improvement work has been carried out.
The Manager of Mining Engineering has determined that it is necessary to apply for an
exemption to operate with elevated levels of methane in the intake roadway.
As a result you have been asked to participate in a risk assessment as part of the
exemption process. In preparation for the intended risk assessment, the Manager of
Mining Engineering has requested that you provide summary information of the following:
a) Who would you expect to be included in the risk assessment?(1 mark)
b) State the level CH4 permitted by the Coal Mine Health and Safety Regulation 2006
at the commencement of a hazardous zone. (1 mark)
c) What level of CH4 would you recommend be applied for as part of the exemption for
the commencement of the hazardous zone, where non explosion protected plant
will be installed? (1 mark)
d) What equipment would you expect to be required at the section substation as a
means to safeguard electrical equipment? (1 mark)
e) What equipment would you expect to be required outbye as a means to safeguard
other electrical equipment installed within the gate road? (1 mark)
f) On the ‘Boutique Mine 107’ panel layout drawing provided, show where each item
of electrical safety plant will be installed, show trip levels and any electrical linkages
for tripping. State all assumptions made. (5 marks)
Page 4 of 7
Application of Electrical Engineering to Mining
QUESTION 4 (10 marks)
a) With respect to the most prevalent flammable gas encountered in an
underground coal mine, supply the following information: (4 marks)
i. Name of the gas.
ii. Chemical composition.
iii. Upper explosive Limit.
iv. Lower explosive limit.
v. Most explosive mixture.
vi. Most easily ignited mixture.
vii. Minimum ignition energy.
viii. Ignition temperature.
b) Draw a typical group 1 Exd flange joint as per the requirements of
AS/NZS600079.1:2007 labeling and describing critical dimensions. (2 marks)
c) Name and describe the principles of each of the following methods of
explosion protection techniques. (2 marks)
i. Ex d
ii. Ex s
d) When reading an explosion protection certificate of conformity, what would the
following marking tell you: Aus Ex04.1234X Exd I T4 IP66? (2 marks)
Page 5 of 7
Application of Electrical Engineering to Mining
QUESTION 5 (10 marks)
Clause 19(1)(c) of the Coal Mine Health and Safety Regulation 2006 refers to the
use of electrical plant only of a gazetted type in a hazardous zone. The Gazette
Notice 10 (25 January 2008 pp. 181 - 182) details the types and requirements for
electrical plant that may be used in the hazardous zone.
a) Nominate the types of certification allowed to be used as a function of the gazette
notice. (4 marks)
b) This gazette notice makes reference to voltages that exceed 1200 volts and 4000
volts.
i. What do these voltages relate to? (2 marks)
ii. If a mine is looking at introducing voltages that exceed these values what is
required and when must this occur? (2 marks)
c) Your Manager of Mining Engineering wishes to split a coal pillar using a continuous
miner on the intake roadway to an operating longwall panel. What steps would you
take as Manager of Electrical Engineering to ensure that the requirements of this
gazette are complied with at your mine (2 marks)
Page 6 of 7
Application of Electrical Engineering to Mining
QUESTION 6 (10 marks)
A centrifugal pump operating at an efficiency of 65% raises 7500 litres of water per
minute through a head of 300 metres. The pump is driven by a three-phase induction motor running at 1440rpm, has an efficiency of 85% and a power factor of 0.88. Assume the density of the mine water to be the same as that of pure water Document any assumptions made in your calculations.
Formula
Power = gHQ
Where g = acceleration due to gravity
H = vertical height
Q = flow rate
Using the information given above, calculate the following:
a)
The power of the driving motor. (2 marks)
b)
The torque in Nm developed by the motor. (2 marks)
c)
What size drive motor in kW and supply voltage would you choose for this
installation? (2 marks)
d)
Calculate the full load current of the drive motor. (2 marks)
e)
The weekly energy consumption in kWh if the pumping operation is carried out
100hrs per week. (2 marks)
END OF QUESTIONS
Page 7 of 7
(CEE 2)
NSW Coal Competence Board
EXAMINATION FOR CERTIFICATE OF COMPETENCE AS Mine Electrical Engineer
(Coal Mine Health and Safety Act 2002)
1.30pm – 4.30pm, 17 August 2011
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 the Occupational Health and Safety Regulation
2001.
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. Clearly state any assumptions you make
in answering the questions. Questions are to be answered as a prospective
manager of electrical engineering at a NSW mine.
•
•
•
•
Examination time 3 hours.
Each question is designed for a 15 minute answer only.
Candidates should attempt all questions.
Candidates must mark each answer page with their Candidate Examination
Number.
• All questions are allocated with their respective marking value.
Page 1 of 13
Legislation and Standards applicable to Underground Coal Mines
QUESTION 1 (10 marks)
You are the Manager of Electrical Engineering at an underground mine and have
been informed, on arrival at the mine, that during the night shift a pump motor was
replaced on a breaker line support (BLS). The new motor had three gland entries in
the motor terminal box and the electrician identified that it had been supplied with
two plastic blanking plugs which had been painted the same colour as the motor
junction box.
The electrician replaced the plastic blanks associated with the new motor with the
correct explosion protected blanks (Exd) and checked a second in-service BLS
pump motor and found that two plastic blanking plugs were still in place on the
Junction box. The electrician has tagged the BLS out of service and the mine is
awaiting your advice.
Note
You know that the BLS has been in service for six weeks and the machine had
undergone your site ‘introduction to site inspection’.
a) Who should be notified of this incident and in what time frame? (3 marks)
b) Knowing that the machine had just completed a full overhaul by a licensed
workshop, how would you address this issue with the workshop? (4 marks)
c) What documents or systems would you review or consider implementing on
your site following your investigation? (3 marks)
Page 2 of 13
Legislation and Standards applicable to Underground Coal Mines
QUESTION 2 (10 marks)
You are the Manager of Electrical Engineering at an underground mine that reticulates high voltage to transportable transformer substations at various locations in the mine. You are developing a High Voltage Safety Management Plan (HVSMP) for the mine. Give a description of how you intend to address the following areas. a)
Detail the scope of the HVSMP. (2 marks) b)
Competence of personnel that will conduct high voltage work. (2 marks) c)
Work practices and procedures. (2 marks) d)
Fitness for purpose of switchgear and safety equipment. (2 marks) e)
Documentation that you will require as part of your HVSMP. (2 marks) Page 3 of 13
Legislation and Standards applicable to Underground Coal Mines
QUESTION 3 (10 marks)
AS3000:2007 Wiring Rules details the following clauses. For each of these clauses
describe how you would apply this to your operation to enable compliance.
(a) Clause 1.5.4.1 - Protection shall be provided against dangers that may arise
from contact with parts of the electrical installation that are live in normal
service. (2 marks)
(b) Clause 1.5.5.1 Protection shall be provided against dangers that may arise
from contact with exposed conductive parts that may become live under
fault conditions. (2 marks)
(c) Clause 1.8 – All electrical installations and any alterations additions and
repairs to electrical installations shall, prior to being placed into service or
use, be inspected as far as practicable and tested to verify that the
installation meets the requirements of this standard as applicable. (2 marks)
(d) Clause 4.1.2 (a) - Enable the electrical equipment to function properly under
external influences to which it is expected to be exposed. (2 marks)
(e) Clause 2.3.1 - Electrical installations shall be provided with devices to
prevent or remove hazards associated with the electrical installation and for
maintenance of electrically activated equipment. (2 marks)
Page 4 of 13
Legislation and Standards applicable to Underground Coal Mines
QUESTION 4 (10 marks)
AS/NZS 3800:2005 Electrical equipment for explosive atmospheres—Repair and
overhaul sets out requirements for electrical equipment designed for use in
hazardous areas of underground coal mines.
a) As part of your standards of engineering practice (SEP) for your mine, when
would you expect or require an over pressure test be conducted on an Exd
enclosure at a licensed repair workshop? (2 marks)
b) Describe the methods for testing flameproof joints for straightness as
detailed in Appendix E of the standard. (2 marks)
c) Appendix D describes the marking of overhauled equipment. List the
minimum requirements for marking of overhauled equipment. (2 marks)
d) List the information that should be presented on the Repair/Overhaul and
Examination Report. (2 marks)
e) What are the key requirements for facilities that conduct overhauls on
explosion-protected electrical equipment? (2 marks)
Page 5 of 13
Legislation and Standards applicable to Underground Coal Mines
QUESTION 5 (10 marks)
Clause 19 (i) (i, ii, iii) of the Coal Mine Health and Safety Regulation 2006 calls for:
The provision of effective earthing, including the following:
i)
the minimisation of risk from touch, transfer or step potential,
ii) the prevention of the effects of lightning being transferred to the
underground parts of the coal operation,
iii) the limitation of earth fault currents to mobile plant fed via flexible cables
and to electrical plant in the underground parts of the coal operation
a) What would you do for each of the above points now and the future to
confirm compliance to these clauses? (3 marks)
b) Sketch in an engineering manner a typical earth grid you would find in place
at a 2 MVA, 11kV/415V substation on the surface of the mine, showing the
High and Low Voltage earth positions as well as the lightning earth
arrangement. Label all components and explain any assumptions you have
made on your drawing. (5 marks)
c) What would be your signs and label requirements for the substation and
what would you base this requirement upon? (2 marks)
Page 6 of 13
Legislation and Standards applicable to Underground Coal Mines
QUESTION 6 (10 marks)
You have just arrived at a mine as the Manager of Electrical Engineering and have
identified that there are a large number of different power lines that cross the site.
It is evident that many areas underneath the power lines are used by large mobile
plant as part of exploration work on a regular basis.
a) How would you manage this scenario in the first instance? (2 marks)
b) What systems would you want implemented for your site? (2 marks)
c) How would you go about this given that the mine is happily operating under
the current system? (2 marks)
d) How do you convince a reluctant coal operator to change the existing
system? (2 marks)
e) What would be your last resort response if there was no commitment to
change? (2 marks)
Page 7 of 13
Legislation and Standards applicable to Underground Coal Mines
QUESTION 7 (10 marks)
You are a Manager of Electrical Engineering at a coal operation. The Maintenance
Manager has consulted with you as part of a review of the ‘plant introduction to site
process’, and he is seeking your advice for the electrical safety requirements for
the specification of a mobile 400 amp generator welder.
a) What standards and references would you use to provide your response? (1
mark )
b) What specific electrical requirements would you document for inclusion in
the specification? (2 marks)
c) The Maintenance Manager has asked for your advice on purchasing a
multipurpose unit that electrode welds, MIG welds, has 240 volt auxiliary
power and can supply compressed air for use in the workshop. What would
be your advice for this unit? (2 marks )
d) Outline welding category levels and designate these areas on your site. (3
marks)
e) What processes would you apply before allowing a contractors welding
machine to your site and how would this differ from welding plant owned by
the mine? (2 marks)
Page 8 of 13
Legislation and Standards applicable to Underground Coal Mines
QUESTION 8 (10 marks)
Clause 207 (4) of the Occupational Health and Safety Regulation 2001 (OHSR)
requires that: “electrical work on an electrical installation may be carried out while
the circuits and apparatus of the part of the installation that is being worked on are
energised if it is necessary to do so in the interests of safety and the risk of harm
would be greater if the circuits and apparatus were de-energised before work
commenced”.
a) List four requirements of the OHSR for mine sites to conduct live work if the
risk of harm would be greater if the circuits and apparatus were deenergised before work commenced. (4 marks)
b) Nominate where you would permit live work occurring at your mine if the risk
of harm would be greater if the circuits and apparatus was de-energised
before work commenced (1 mark)
Notice is required to be given before the implementation of clause 207 (4)
for mine site only.
c) Who is the notice to be given to and in what time period? (2 marks)
Clause 208 An employer must ensure that persons conducting tests for the
integrity and operability of energised circuits and apparatus of an electrical
installation at a place of work conduct the tests in a safe manner.
d) List three requirements that the employer must ensure? (3 marks)
Page 9 of 13
Legislation and Standards applicable to Underground Coal Mines
QUESTION 9 (10 marks)
As the Manager of Electrical Engineering an underground mine you have been
asked to provide your specific requirements for an external emergency stop system
on a surface substation.
a) Write in point form your considerations prior to documenting your
specification. (1 mark)
b) Write a brief specification including any documents you would need to
reference. (4 marks)
c) List your commissioning tests you would require before hand over. (3
marks)
d) What maintenance inspection criteria would you apply to the circuit? (2
marks)
Page 10 of 13
Legislation and Standards applicable to Underground Coal Mines
QUESTION 10 (10 marks)
With the aid of sketches explain:
a) the purpose and operation of spark test apparatus used in the testing of
intrinsically safe apparatus nominated with AS/NZS60079.11:2006
Explosive atmospheres – Equipment protection by intrinsic safety i. (5
marks)
b) the process of pressure testing an Exd enclosure and nominate where the
test pressure is derived from. (5 marks)
QUESTION 11 (10 marks)
With the aid of sketches (if required) describe what is meant by
a)
Pressure piling with respect to flameproof enclosures Exd. (2 marks)
b)
State the minimum number of threads to be engaged on flameproof
enclosure Exd for threaded entries eg: gland. (1 mark)
c)
How many faults are applied during testing of Exi (a) and (b)? (2 marks)
d)
What is meant by the term systems and entity concepts with respect to
intrinsically safe systems? (4 marks)
e)
If you read in a hazardous area assessment report ‘Zone 20’ what would
you understand it to mean? (1 mark)
Page 11 of 13
Legislation and Standards applicable to Underground Coal Mines
QUESTION 12 (10 marks)
As the Manager of Electrical Engineering, you are aware of ongoing issues with the
reliability of some components on your Powered Roof Support Control System.
An Engineer from the OEM attends site to show you a replacement IS solenoid and
a new type of cable they are proposing to retrofit to your longwall.
The Engineer is stating it is compatible with the existing power supply
The Entity concept parameters they have detailed are:
IS POWER
NEW IS
SUPPLY
SOLENOID
Uo
12V
Ui
14V
Io
2A
Ii
2.5A
Co
15uF
Ci
20uF
Lo
95uH
Li
5uH
New Cable
L/R 50uH/ohm
Cable Parameters are: Capacitance = 0.1uF/m
Inductance
= 0.9uH/m
L/R
= 13uH/ohm
Using the information stated above:
a) Can the solenoid be used with the existing IS power supply? Justify your
answer. (2 marks)
b) The solenoid is controlled via an output of the IS controller mounted on each
roof support. The output contact is not shown in the parameter drawing
above. Does it need to be considered when evaluating the circuit
parameters? (1 mark)
Page 12 of 13
Legislation and Standards applicable to Underground Coal Mines
QUESTION 12 (continued)
c) If you are considering the inductance of the circuit only – what can the
maximum length of the cable be? (2 marks)
d) What information would you expect to be displayed on the nameplate of the
solenoid? (3 marks)
e) You ask the Engineer why you need the new cable, and cannot use the
existing cables and he is not certain why and states that “the engineers at
head office said you have to use the new cable”.
This represents a considerable cost, as there are 150 roof supports with 10
solenoids per support.
On checking the original parameter drawings in the Safety File, you note the
following cable parameters: C = 0.5uF/m; L=2uH/m; L/R = 40uH/ohm.
In terms of ensuring IS integrity – can the existing cable be used? Justify
your answer. What other reasons may prompt the supplier to say the cables
need to be changed? (2 marks)
END OF QUESTIONS
Page 13 of 13
(CEE 3)
NSW Coal Competence Board
EXAMINATION FOR CERTIFICATE OF COMPETENCE AS A Mine Electrical Engineer
(Coal Mine Health and Safety Act 2002)
1.30pm – 4.30pm, 17 August 2011
Legislation and Standards applicable to Surface Coal Mines
INSTRUCTIONS TO CANDIDATES
Unless otherwise stated all references to Regulations are to the Coal Mine Health
and Safety Regulation 2006 or the Occupational Health and Safety Regulation
2001.
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. Clearly state any assumptions you make
in answering the questions. Questions are to be answered as a prospective
manager of electrical engineering at a NSW mine.
•
•
•
•
Examination time 3 hours.
Each question is designed for a 15 minute answer only.
Candidates should attempt all questions.
Candidates must mark each answer page with their Candidate Examination
Number.
• All questions are allocated with their respective marking value.
• Part of the answer for question 2 is to provided on the ‘Boutique surface
reclaim tunnel’ layout drawing and is to be handed in with your answer book
with your candidate number clearly visible
Page 1 of 14
Legislation and Standards applicable to Surface Coal Mines
QUESTION 1 (10 marks)
As the Qualified Electrical Engineer for the coal operation you have been asked to
provide your specific requirements for an external emergency stop system on a
surface substation.
a) Write in point form your considerations prior to documenting your
specification. (1 mark)
b) Write a brief specification including any documents you would need to
reference. (4 marks)
c) List your commissioning tests you would require before hand over. (3
marks)
d) What maintenance inspection criteria would you apply to the circuit? (2
marks)
Page 2 of 14
Legislation and Standards applicable to Surface Coal Mines
QUESTION 2 (10 marks)
You are the Qualified Electrical Engineer for the coal operation that is undergoing
a major upgrade to the surface Coal Handling and Preparation Plant (CHPP) for
which you have responsibility. The upgrade will involve the construction of a
reclaim tunnel that will have three valve entries fitted with hydraulically controlled
gates and power pack adjacent to the gates. The power pack is installed in the
coal valve chamber which is 3 metres above the conveyor belt and out of the
ventilation flow.
You have been asked by the mine operator to provide your electrical requirements
to the designer for the tunnel. State any other requirements you have for the
designer to include or consider within the design.
a) What are the requirements you would specify to be carried out as part of the
design stages? (3 marks)
b) On the drawing ‘Boutique surface reclaim tunnel’, show the locations and types
of monitoring equipment will you require to be installed within the tunnel and any
other items of plant you require within the tunnel? (5 marks)
c) For any monitoring equipment you have nominated, what explosion protection
group classification is acceptable for use? (1 mark)
d) Who would be permitted to maintain the type of equipment selected in this area?
(1 mark)
Page 3 of 14
Legislation and Standards applicable to Surface Coal Mines
QUESTION 3 (10 marks)
AS3000:2007 Wiring Rules, details the following clauses. For each of these
clauses describe how you would apply this to your operation to enable compliance.
a) Clause 1.5.4.1 - Protection shall be provided against dangers that may
arise from contact with parts of the electrical installation that are live in
normal service. (2 marks)
b) Clause 1.5.5.1 Protection shall be provided against dangers that may arise
from contact with exposed conductive parts that may become live under
fault conditions. (2 marks)
c) Clause 1.8 – All electrical installations and any alterations additions and
repairs to electrical installations shall, prior to being placed into service or
use, be inspected as far as practicable and tested to verify that the
installation meets the requirements of this standard as applicable. (2 marks)
d) Clause 4.1.2 (a) - Enable the electrical equipment to function properly under
external influences to which it is expected to be exposed. (2 marks)
e) Clause 2.3.1 - Electrical installations shall be provided with devices to
prevent or remove hazards associated with the electrical installation and for
maintenance of electrically activated equipment. (2 marks)
Page 4 of 14
Legislation and Standards applicable to Surface Coal Mines
QUESTION 4 (10 marks)
You are the Qualified Electrical Engineering at a surface coal operation when you are advised that a conveyor belt within the coal handing plant as failed to stop when a stop lanyard was operated. a)
What steps will you now take with respect to this incident? (3 marks) b)
What are your responsibilities as far as legislation is concerned? (2 marks) c)
Who would you involve in the investigation? (2 marks) d)
What key areas would your investigation focus towards? (3 marks) Page 5 of 14
Legislation and Standards applicable to Surface Coal Mines
QUESTION 5 (10 marks)
Clause 19(i) (i, ii, iii) of the Coal Mine Health and Safety Regulation 2006 calls for:
The provision of effective earthing, including the following:
i)
the minimisation of risk from touch, transfer or step potential,
ii) the prevention of the effects of lightning being transferred to the
underground parts of the coal operation,
iii) the limitation of earth fault currents to mobile plant fed via flexible cables
and to electrical plant in the underground parts of the coal operation
a) What would you do for each of the above points now and the future to
confirm compliance to these clauses? (3 marks)
b) Sketch in an engineering manner a typical earth grid you would find in place
at a 2 MVA, 11kV/415V substation on the surface of the mine, showing the
High and Low Voltage earth positions as well as the lightning earth
arrangement. Label all components and explain any assumptions you have
made on your drawing. (5 marks)
c) What would be your signs and label requirements for the substation and
what would you base this requirement upon? (2 marks)
Page 6 of 14
Legislation and Standards applicable to Surface Coal Mines
QUESTION 6 (10 marks)
You have just arrived at a new site as the Qualified Electrical Engineer and have
identified that there are a large number of different power lines that cross the site.
It is evident that many areas underneath the power lines are used by mobile plant
on a regular basis.
a) How would you manage this scenario in the first instance? (2 marks)
b) What systems would you want implemented for your site? (2 marks)
c) How would you go about this given that the mine is happily operating under
the current system? (2 marks)
d) How do you convince a reluctant coal operator to change the existing
system? (2 marks)
e) What would be your last resort response if there was no commitment to
change? (2 marks)
Page 7 of 14
Legislation and Standards applicable to Surface Coal Mines
QUESTION 7 (10 marks)
You are a Qualified Electrical Engineer at a surface coal operation. The
Maintenance Manager has consulted with you as part of a review of the plant
introduction to site process, and he is seeking your advice for the electrical safety
requirements for the specification of a mobile 400 amp generator welder.
a) What standards and references would you use to provide your response?
(1 mark )
b) What specific electrical requirements would you document for inclusion in
the specification? (2 marks)
c) The Maintenance Manager has asked for your advice on purchasing a
multipurpose unit that electrode welds, MIG welds, has 240 volt auxiliary
power and can supply compressed air for use in the mines service bay.
What would be your advice for this unit? (2 marks )
d) Outline welding category levels and designate these areas on your site. ( 3
marks )
e) What processes would you apply to a contractors welding machine before
allowing it to be used on your site? (2 marks)
Page 8 of 14
Legislation and Standards applicable to Surface Coal Mines
QUESTION 8 (10 marks)
Clause 207 (4) of the Occupational Health and Safety Regulation 2001 (OHSR)
requires that: “electrical work on an electrical installation may be carried out while
the circuits and apparatus of the part of the installation that is being worked on are
energised if it is necessary to do so in the interests of safety and the risk of harm
would be greater if the circuits and apparatus were de-energised before work
commenced”.
a) List four requirements of the OHSR 207 for mine sites to conduct live work
if the risk of harm would be greater if the circuits and apparatus were deenergised before work commenced. (4 marks)
b) Nominate where you would see live work occurring at your mine if the risk
of harm would be greater if the circuits and apparatus was de-energised
before work commenced. (1 mark)
Notice is required to be given before the implementation of clause 207 (4) for mine
site only.
c) Who is the notice to be given to and in what time period? (2 marks)
Clause 208 - An employer must ensure that persons conducting tests for the
integrity and operability of energised circuits and apparatus of an electrical
installation at a place of work conduct the tests in a safe manner.
d) List three requirements what the employer must ensure. (3 marks)
Page 9 of 14
Legislation and Standards applicable to Surface Coal Mines
QUESTION 9 (10 marks)
You are the Qualified Electrical Engineer at a large open-cut mine. When walking
through the Technical Services Department you overhear the Technical Services
Manager mention the words “remote-controlled loader”. On enquiring for more
information you are informed:
“Our company has signed a Memorandum of Understanding (MoU) with a major
overseas equipment supplier – The Wunhung Sewing Machine Company - a joint
venture to introduce their revolutionary technology into the Australian market”.
After further enquiries you find out that:
“The trial involves a 50T payload electric loader and a 190T electric truck from the
Wunhung range. Their remote control technology involves the integrated
application of wireless voice over internet protocol (VoIP) technology, global
positioning systems (GPS), and collision avoidance systems (CAS). The
equipment has been in limited operation in their home market for the last couple of
years, but it is new to Australia”.
“The machines will be used to load and transport coal in a trial area out of the
South Pit. It is intended there will be segregation from other parts of the operation,
but there is the possibility of some interaction of machinery at the ROM hoppers.
The trial will run for two to three months”.
“The equipment will be turning up on site in approximately five weeks”.
“The Board and the CEO are particularly interested in seeing this trial proceed, as
they see enormous potential in the technology”.
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Legislation and Standards applicable to Surface Coal Mines
QUESTION 9 (continued)
a) Outline the process you would follow to manage the introduction of this
equipment to site. (3 marks)
b) In undertaking the introduction process, list what legislation, Australian
Standards and NSW Mine Safety Guidelines would you consider to be
applicable to the equipment? (2 marks)
c) An initial enquiry reveals the machines have not been manufactured to
comply with relevant codes and standards. The supplier shows little
inclination to make changes to the machine to achieve compliance, (as they
have already been built) and the General Manager is becoming extremely
frustrated at the “brick walls” he sees being erected before the equipment
even arrives on site. How will you manage these non-compliances so that
the safe operation of the equipment is not compromised? (3 marks)
d) List the documentation you would expect the supplier to provide with the
equipment. (2 marks)
Page 11 of 14
Legislation and Standards applicable to Surface Coal Mines
QUESTION 10 (10 marks)
The coal operator has asked you to evaluate a new electric drive rear dump truck
for use at your operation:
a) In point form, what would be your specific requirements for the electrical
systems on the machine? (2 marks)
b) For each of the above requirements state the reason for your choice. (2
marks)
c) What specific safety circuits would you ask be fitted to the machine and the
reason for your requirements? (2 marks)
d) How do you assess that you received the plant you asked for? (2 marks)
e) What process would you follow for isolation on the machine? (2 marks)
Page 12 of 14
Legislation and Standards applicable to Surface Coal Mines
QUESTION 11 (10 marks)
As the Qualified Electrical Engineer for the mine it is evident that compliance to
Electrical Standards is falling at a rate that has become unacceptable after a
number of electric shock incidents:
a) What other installation measures could be applicable in this scenario? (2
marks)
b) How can you improve the overall compliance of the installations? (2 marks)
c) What are your responsibilities as the Qualified Electrical Engineer in this
regard? (2 marks)
d) List some of the causes that could let the installation get into a poor state?
(2 marks)
e) How do you deal with non-compliant installations where standards are not
being met? (2 marks)
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Legislation and Standards applicable to Surface Coal Mines
QUESTION 12 (10 marks)
A centrifugal pump operating at an efficiency of 65% raises 7500 litres of water per
minute through a head of 300 metres.
The pump is driven by a three-phase induction motor running at 1440rpm, has an
efficiency of 85% and a power factor of 0.88. Assume the density of the mine water to be the same as that of pure water. Document any assumptions made in your calculations. Formula Power = gHQ Where g = acceleration due to gravity
H = vertical height
Q = flow rate
Using the information stated above, calculate: a)
The power of the driving motor. (2 marks) b)
The torque in Nm developed by the motor. (2 marks) c)
What size drive motor in kW and supply voltage would you choose for this installation? (2 marks)
d)
Calculate the full load current of the drive motor. (2 marks)
e)
The weekly energy consumption in kWh if the pumping operation is carried
out 100hrs per week. (2 marks)
END OF QUESTIONS
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