AADC CONSTRUCTION QUESTIONAIRES
For what purpose we use the Earth Fault Indicator (EFI) device?
o Fault indicators are used to locate earth-faults or short-circuit in power distribution
networks. The aim of using fault indicators is to have a reliable, cost efficient and fast
indication of the fault location in the network.
o In open ring systems, the damaged line section can be disconnected from the network,
as soon as a fault is located. While the service team repairs the damaged cable, the rest
of the network can be powered up. In this way, the down-time of the network can be
minimized to increase the quality of the infrastructure.
How the EFI device works?
o If there is any fault in a cable, there will be an imbalance in the total amount of current
in a cable instead of zero. The sensor CT will sense that imbalance and hence the device
will start blinking.
o The last device that's not blinking shows that the faulty cable is behind this substation
and in between the blinked device and the device that's not blinking.
What are the safety documents you will need to complete EFI Project (explain)?
o LAP : nature of works related to site survey and installation and testing of EFI without
fixing CT on powered cables
o PTW: nature of works related to power and sensor CT fixing over a power cable
Can the competent person be the authorized person at same time?
o COMPETENT PERSON: a person who has sufficient technical knowledge and experience
to recognize and avoid danger and been appointed by writing to carry out defined scope
in addition to receipt and clearance of safety document .
o Authorized person: in addition to having duties of competent person, he is appointed in
writing to carry defined scope this may include operation of equipment preparation,
issue and cancellation of safety document
o He can have all the certificates and the authorities, but he can either a competent
person who receives the permit from another authorized one, or the authorized person
who issue it for another competent person.
In case that the competent person has to go for other work what shall he do?
o Stop any running activates under the opened permit
o Explain to authorize person the reason to leave.
o Follow procedures of transferring the permit to another competent person
What is the civil clearance?
o Civil clearance is the approval or acceptance for installing equipment inside the
substation. There are several mandatory and optional points to be checked and verified,
civil clearance will be given after clearing all the mandatory points and should be
completed, inspected and approved by Consultant before insertion & assembly of the
electrical equipment to avoid any damage in the electrical equipment.
What are the types of earthing and minimum size of cable for each type?
o Primary Earth – 70 sqmm
o Additional Earth – 25 sqmm
o Portable Earth
Why VLF preferred over DC for high voltage test of cables?
o Applying DC High voltage will result in a stress distribution very different from that in AC
service condition. When AC High voltage is applied to a cable, space charges will be
created with in the insulation due to voids present in it and this space charge will remain
for long time even after discharging also. When the cable is energized, these space
charges will create dangerous uneven stress on the insulation to reduce the life of cable.
o Also, with DC HV test some serious fault or nick in the insulation cannot be detected,
instead cable will pass the test and will be failed when the cable put under live
condition.
o But, VLF test will create almost same effect that of power frequency on insulation of the
cable.
What is the applied voltage for each size of cable during VLF test?
Applied voltage is 3Uo, where U0 is phase voltage
* IEEE 3Uo peak
o For 11KV – 19 KV peak
o For 22KV – 38 KV peak
o For 33KV – 57 KV peak
* IEC Std. 3Uo rms
o For 11KV – 19 KV rms
o For 22KV – 38 KV rms
o For 33KV – 57 KV rms
Procedure for excavation during shut down including permit procedure (from application of permit
tell closing it)?
o First of all, study and analyze the nature of work and decide the type of permit need to
be obtained.
o Obtain NOC from all the utilities and also the route map of cable to be exposed.
o Prepare and submit the application for permit to consultant/client mentioning all the
necessary details for approval.
o Safety document will be issued to the competent person and he will be responsible for
all the activities in site.
o Competent person has to conduct toolbox talk before commencing the work, after
receiving the permit.
o Trial pit need to be taken prior to do excavation.
o Only manual excavation is allowed, if any existing utility is found in the cable route.
o Complete the excavation activity, withdraw the working team from site and close the
permit.
Draw the cable trench details & Spacing between each cable for different voltage level
o For LV cable – 30cm
o For 11 KV cable – 40cm
o For 33 KV cable – 50cm
Tests during installation of switchgear?
o Insulation Resistance
o Busbar contact resistance measurement
o Torque
Minimum clearance required between (wall & MV panel) & (wall & LV panel) (MV panel & LV panel)?
o Between Wall & MV Panel – Min. 1 Mtr.
o Between wall & LV Panel – Min. 80 CM (As per ADDC, Regulation and supervision
bureau, RSB- 75 Cm )
o Between LV Panel & LV Panel – Min. 1.5Mtr. (As per ADDC, Regulation and supervision
bureau, RSB )
o Between 11 KV Panel & LV Panel- Min. 1.5 Mtr. (Additional space to consider if required
for drawable type breakers)
o Between 22 KV Panel & LV Panel- Min. 2 Mtr. (Additional space to consider if required
for drawable type breakers)
Define your responsibilities as a construction manager and your daily duties?
o Study and analyze project baseline and schedule received from PM, enabling him
calculate required manpower and machineries, in addition to plan mobilization, site
establishment, site survey, and all requirements to commence planned activities at site.
o Prepare (monthly basis) manpower and machineries mapping through PM, who will
submit the same officially.
o Developing the program of construction work and strategy for making the project
happen as Project Plan.
o Studies and analyses all inputs to reduce risk and maintain construction program as
planed time, quality and budget.
o Make sure that all docs and drawings approvals, NOCs, and related authority permit, are
available prior to site work activities.
o Manage project resources and dispatch to construction sites.
o Lead and control all site activities implemented by GTGC team or subcontractors, and do
required coordination and guidance to make sure that all site activities are moving as
per project plan.
o Coordination between site office and engineering office for reviewing the Construction
drawings against design drawings
o Make sure that work is executed as per approved method statement and safety
precaution, which will maximum maintain personnel, equipment, and environment
safety.
o Certify all executed work through inspections in coordination with QA/QC, and keep
close coordination with consultant and client to achieve full satisfactory.
o Provide support and required guidance to site team in order to help them complete
their tasks, and improve their skills and capabilities.
o Managing for material requirement and availability for construction activity.
o Follow up with planning department to keep project on track by monitoring & managing
work progress based on planning schedule
o Monitoring site progress ensuring for the efficiency for equipment’s and manpower to
ensures that the duration of each activity will meet the required time frame in the
schedule
o Managing Subcontractors including scope, activity, reporting, works certify and other
related construction activity.
o Submit internal and official progress reports on weekly and monthly basis as per
management, company policy, and client requirements.
o Communicating with stakeholders, client, subcontractors, management, suppliers, the
public and the workforce.
o Analyzing inputs and outputs on frequently period to determine the productivity of
recourses and required techniques to improve productivity and quality of developers.
o Develop, analyze and review of lesson learned and utilizing the same for next activity
and projects improvement.
What is the minimum duration needed to complete one brick built substation as a civil work?
For One precast Sub Station with Raft Foundation.
o As pure civil works, Including steel doors & gratings & finishing Min. 23 to Max-30 Days
required.
o Exclusions:-Soil Investigation, Design& approval, NOC, building permit, land cutting or
filling & Levelling soil improvement, Piling works
What is the duration to complete assembly of all equipments inside the substation?
o based on project time schedule and activates breakdown .each activity may vary from
one site to another based on Number of Panels and type of Equipment’s required to be
installed
o (4 panel) Brick built SS: Assembly works of Equipment (TR, SWG, and LV Panel) : 2.5 days
What are the tests for the equipment and duration needed to finish all this tests?
o Based on project time schedule and testing activates breakdown, (4 panel) Brick built SS
Pre commissioning tests: 1.5 days (EXCLUDED DC System)
If some materials which your company placed the PO of it already and delivery delayed which will
cause delay of other work what will you do to overcome this delay?
o First thing is to analyze the impact of delayed delivery on the project milestones or end
date. The impact can be ignored, if you have time buffer or slack (total float) available to
accommodate this delay without delaying any successor activities in on critical path.
o In case of delay in project end date, the matter should be officially escalated to the
client through proper channel with all the supporting documents endorsed by the
supplier. The change in the schedule shall be approved through integrated change
control process.
o After approval, reflect the change in baseline/subsidiary plan.
o Update change log and lesson learned.
Generally if some delay happen in one activity during the project how to compensate this delay and
how to speed the progress? How to control the quality in the same time?
1- First of all, we should investigate regarding this activity delay, and find out reasons (resources
not sufficient, resources not qualified, improper site control, quality issues and delays or delay
of approvals and authority permits), responsible party or department, consequences, and
impacts, then report this delay to management.
2- Check whether it will affect the critical path or delay the whole project, to know its impact
value.
3- Most commonly, Schedule compression techniques are used to shorten the schedule duration
without reducing the project scope in order to meet schedule constraints and imposed dates.
For example crashing technique by increasing resources, working hours with incremental cost
and fast tracking technique by doing the appropriate activities in parallel.
4- Keep full control on any expected scope creeping or gold plating.
5- Quality shall be maintained by developing comprehensive testing strategy, applying quality
assurance rules and procedures.
How you will install PU?
o 1-making the site survey.
o 2-Marking the site as per the approved drawings.
o 3-preparing all dead work as per approved drawings.
o 4-making compaction (compaction test) and preparing the BCC.
o 5-Installation of the foundation & applying water proofing
o 6-Installion of the package unit.
o 7-Termination
What the bus bar ratings for LV panel and how you will determine the rating if the LV panel is life?
o Name plate of LV panel includes the bus bar rating and we can take full details while
main panel is live
Procedure of taking shut down?
o The person who is going to receive the safety document should be competent from the
client, and the activity must come under mentioned scope in certificate
o Prepare and submit the permit application indicating all necessary details (substation
name, equipment name, scope of work, safety precautions, date, duration, etc.,) to
client for approval and processing the shutdown request.
o After confirming outage from the operation, authorized person will give the shutdown
and will apply all the safety precautions, will hand over the equipment and will issue the
permit for the competent person.
o After receiving the safety document from authorized person, work can be started.
How many earth points in LV and PU?
o In LV Panel, 2 Earth points; on either sides
o In PU, 2 Earth points for Body Earthing & 1 Earth point for Neutral Earthing
How many way is the LV panel?
o In total, there are 18 ways; 9 ways in each outgoing feeder and the rating of buss bar is
2700 A
Can you take shutdown for MV & LV in same time?
o Yes it can
What is the minimum clearance for PU & LV?
o From package unit to the fence the minimum clearance is 1.5 m, for LV 1 m from the
accesses and 0.75 m from the wall
Size of cable for the HV side in PU?
o P/U is part from loop, cable size as per loop design, it can be 3C, 300 sqm/3C, 240 sqm
even 3C, 185 sqm
What is the cable size from transformer to LV panel?
From transformer to LV panel, 1C 630sqmm cable is used and no. of runs depends on the rating
of transformer.
o 500KVA TR – 1 run for each phase + 1 run for neutral
o 1000KVA TR – 2 run for each phase + 1 run for neutral
o 1500KVA TR – 3 run for each phase + 2 run for neutral
How you will install the LV panel and make assembly?
o First of all, for installing panels inside the substation, civil clearance need to be
obtained; for newly constructed substations.
o For lifting, crane with appropriate capacity have to be chosen depending on the weight
of crate.
o Check and confirm the access to enter the panel inside the substation, also verify the
platform for unloading panels, prior to insertion.
o Do marking inside the station as per the approved layout.
o Insert panels and position accordingly.
o Do inter panel connection if the panel is 2 or more part.
o Anchoring the panels down the floor.
o Bus bar interconnection, torqueing (as per the standard value) and marking the bolts.
o Clean the panel inside prior for the closing cover.
Can you make excavation inside the fence of PU with only LAP safety document?
o In case of PU site plans cover the working area then the answer is Yes , in case not the
Complete NOC process shall take place and answer will be No
Can you open two permits in same time?
o It is not allowed to open two permits in same time for same person, as per SSR and you
have to be in the location where you open the permit
If you have emergency and the shutdown is going on what will you do?
o Inform another Competent Person through authorized person
How are you doing the site survey?
o Site survey shall be done on specific SOW and defined locations in the contract, by
approved Method of statement and site survey format from client. Trail pits, visual
inspection, site measurement is the main tools to do so
What is Procedures of power transformer installation?
o Ensure completion of Foundation finishing works and level as well as the
associated metal works such as (checker plate, Gratings).
o Ensure proper site access for machinery and manpower for safe working
area considering the arrangement of temporarily scaffolding and covering of
transformer surrounding trenches.
o Installing of Transformer main tank using proper crane and lifting chakels as per
manufacturers, recommendation and lifting plan as it shall be positioned on
Transformer base in plant yard considering the proper orientation of HV/LV sides
respectively.
o Installation and assembly of Transformer radiators, conservator, bukhloz relays along
with associated piping works between , main tank , breathers, sampling flanges ,etc.. As
per manufacturer recommendation.
o Installation and Assembly of HV/LV Cable end boxes along with its related works for
Bushing, bus bars, arrestors etc. as per manufacturer recommendation.
o Installation and assembly works Transformer auxiliaries and instruments (FANS, OLTC
PANEL) will be installed as per manufacturer’s recommendation cooling fans, oil
circulating pumps, tap changers, level switches, firefighting system etc. are to be
installed.
o Draining of oil from transformer main tank and performing Oil BDV test prior filtration
as per approved SAT procedure followed by filtration and circulation process of
Transformer oil with the right quantity of loose Oil drums followed by conducting oil
BDV after filtration to ensure approved values as per manufacturer recommendation.
o Positioning of transformer wheels followed by locking of it to arrest any movements of
the transformer main tank shall be fixed / anchored in the exact position after verifying
its position with respect to the position & level.
What is pre commissioning test for power transformer?
o Measurement of voltage/Turns ratio
o Measurement of winding resistance
o Vector group test
o Measurement of insulation resistance of the winding between HV, LV and earth
windings and Polarization Index (PI) test.
o Magnetizing Current test
o Short Circuit test
Fiber Optic Cable Laying Procedures
o Safety Precaution
o Conduct a thorough site survey prior to cable placement.
o Do not exceed cable minimum bend radius.
o Do not exceed cable maximum recommended load.
o The figure-eight configuration should be used to prevent kinking or twisting when cable
must be unreeled or backfed.
o Unreeled cable is placed on the surface above the manhole.
o Pulling cable in 100mm duct pipe manhole to manhole.
Tests for Fiber Optic Cable
o Visual Inspection.
o Drum Test
o Post Installation Test
o Splice loss Attenuation Test and Continuity Test of Fibers.
o End-to-End test using Optical time domain reflector - meter (OTDR)
o Splice Loss Analysis
o End to End test using power meter & light source
o Outer Sheath DC Voltage Withstand test
Machineries & Man power needed for the activities and the project?
o Engineer, Supervisor, competent person (permit holder), HSE officer, Technician &
labors
Pulling Machine, cable Trailer, car crane
What is the documents that should be submitted to the consultant when submitting the RFI?
o RFI format, checklist sheet, approved drawing, NOCs, Permits (if applicable), MS
approval & approval of previous activities RFIs.
What is the documents that should be taken with the site engineer while going for inspections?
o RFI, checklist sheet, approved drawing, approved MS.
If you are excavation in an area where water is coming inside the trench what you will do? Where will
you put the water?
o We have to prepare dewatering system & water to be put in nearest sewerage line
In the second day, the water is still coming back again, what you will do in this case?
o We have to lay cables in Tramp, if above the ground
Trail pit is done every how many meters?
o 50 meter
What’s the use of semi conductive material on the cable?
o Redistribute & control the electric field (stress)
What’s the standard we are using for VLF? What the standard for other tests? Exact Names and
Numbers …
o IEC 60502
o IEEE 400.2
