The presentation is based on the discussions about the safety in Power Plants and substations. The presentation is a part of the seminar on Electrical safety and reliability. The reporting of accidents was also discussed at length in the seminar

1. ELECTRICAL SAFETY IN POWER
STATIONS
Manohar Tatwawadi
total output power solutions,
9372167165, PUNE
MAHARASHTRA, INDIA

2. INTRODUCTION
• The criteria of Human Safety from Electric Shock
is very much complex.
• The design of the equipment is done keeping in
view the potential danger to the human life and
property.
• The basic intention of the Law Makers is to deal
with the dangers of Electricity.
• However, due to passage of time, the
technological advances in Electrical Engineering
made the job of Electrical Safety very difficult.
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3. INTRODUCTION
• Inquiries into the cases of Electrical Accidents
reveal the negligence & disregard to the laws and
also casual approach to the loss of human life.
This attitude needs to be changed.
• The Safety Engineering has to be combined with
the Reliability Engineering and Science. If we
practice Reliability Science and construct,
maintain the equipment, it would automatically
take care of the destruction due to accidents and
large breakdowns.
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4. INTRODUCTION
• Only need is to change the outlook towards
human life and values.
• The punishments, which are provided in Acts and
Rules for breach are found to be failure in
Correctional Services.
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5. Electrical Accidents
• Electrical Accidents, unlike most other industrial accidents quite
often happen to professionals, supervisory and working staff. In
some situations, they may be at greater risk than the manual staff.
• If we consider the statistics of the Fatal Electrical Accidents, 35%
accidents are on Supply Company Works and out of these 33%
occur to the working staff of the Supply Company.
• Most of the Non-fatal Electrical Accidents are not reported. The
reported non-fatal accidents are those, which are either to the
Supply Company Workers or with serious injuries to outsides. In this
case, it is very necessary to know the definition of Electrical
Accidents according to the Act of 1910.
• We in India, followed the British made statute of 1910 i.e. Indian
Electricity Act, 1910. This statute was initially prepared in 1884,
then revised in 1903, 1907 and 1909 and finally accepted as Act of
1910.
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6. THE VICTIMS OF ELECTRICAL
ACCIDENTS
1. A person passing on Road & snapped conductor
falling on his head.
2. Person passing by road lifts a charged conductor.
3. Person touching the non-current parts of lines (Supply
Co.)
4. Person contacting water pipes/taps and getting
electrocuted.
5. Person throwing wires/ threads on E.H.V.line.
6. Un-authorised climbing on E.H.V./H.V.lines.
7. Blast of Transformer/ Breakers etc. (oil filled
equipments)
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7. ACCIDENT REPORTING & DEFINITION
OF ACCIDENT
If any accident occurs in connection with the generation,
transmission, supply or use of energy in or in connection
with, any part of the electric supply lines or other works
of any person and the accident results or is likely to have
resulted in loss of human or animal life or in any injury to
a human being or an animals, such person shall give
notice of the occurrence and of any such loss or injury
actually caused by the accident, in such form and within
such time as may be prescribed, to the Electrical
Inspector and to such other authorities as the
appropriate Governments may be by general or special
order direct.
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8. ACCIDENT REPORTING & DEFINITION
OF ACCIDENT
• The definition speaks the real intention of the
Legislators. The words “Likely to have resulted in a Loss
of Human Life & Property” takes complete care of the
possible hazards; either to Human Life or to the
property. It means that the lawmakers considered the
slightest potential danger arising out of Electricity to
the mankind. It speaks for the values of the Human Life
& how the Legislators intended to protect it.
• The detailed regulations i.e. Rules framed under this
Act of 1910 makes obligatory to follow them with same
“SANCTITY” with which the Act was adopted.
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9. STATUTORY REGULATIONS
Indian Electricity Rules – 1956:
1. Rule –3 : Authorization.
2. Rule –29 : Construction, installation, protection, Operation & Maintenance
of electric Supply Lines & Apparatus.
3. Rule –36 : Handling of Electric Supply Lines & Apparatus.
4. Rule –46 : Periodical Inspection & Testing of Consumer’s Installation.
5. Rule –49 : Leakage on Consumer’s Premises.
6. Rule –50 : Supply & use of Energy.
7. Rule –59 : Precautions against failure of Supply – Notice of Failures.
8. Rule –64 : Use of Energy at High & Extra-high Voltage
9. Rule –65 : Testing, Operation & Maintenance.
10. Rule –66 : Metal sheathed Electric Supply Lines-Precautions against excess
leakage.
11. Rule –67 : Connection with earth.
12 Rule –90 : Earthing.
13 Rule –91 : Safety & Protective Devices.
14 Rule –92 : Protection against lighting.
15 Section–33 : Notice of Accidents & Inquiries.
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10. I.E.Rule No. 29, 35 &36
• I.E.Rule No. 29 speaks about the general precautions, in maintenance,
erection construction and operation. All such work, and the procedure
should be such as to confirm to the relevant B.I.S. and further it is
obligatory on the owner of installation to make any activity in respect
of Electrical Installation such that it should prevent danger.
• Rule – 35: All these rules deal with human psychology also. Rule 35
lays down to fix the danger notice on each Medium & High or Extra
High Pressure Installation. From the practical point of view, one thinks
that everybody, who so-ever comes to the Power Station knows the
potential danger from the installation & in this condition, it is a waste
to provide such warning. With this contention, there is no answer, why
the technicians met with Electrical Accident? It is negligence. But when
he reads a Caution, his mind is psychologically prepared to take
adequate care from the proximity of the hazardous Live Part. This
alone allows a person to act rightly with safety.
• Rule – 36: It prescribes the Caution while handling of the Electrical
Conductors & apparatus.
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11. PROTECTION FROM MECHANICAL &
ELECTRICAL INJURY TO WORKMEN
• Any unauthorised person is not permitted to work on live lines. Here, the
authorisation refers to Rule No. 3, Wherein the Manager has to get
himself satisfied that the person, who is authorised to work on particular
job is so competent to take adequate Safety Precautions, for himself & for
others also.
• The Scheme of all the rules is made in such a way that to suit most of the
Contingencies of the Technology in practice. Rules 61, 67, 90 speaks about
the Safety from non-Current Carrying parts, Earthing etc. Principally, Rule
67 is very much improved, and cares for the Human Safety for the persons
in the SwitchYard. A concept of Step & Touch Voltage Ground Potential
Rise due to faults in H.V./ E.H.V. Sub-station is explained. It makes
obligatory for the owner/ manager of the Sub-station to observe the
maximum designed value of Earth Resistance throughout the year, so as to
keep the Step/Touch Potential & Ground Potential Rise within permissible
limits.
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12. PROTECTION FROM MECHANICAL &
ELECTRICAL INJURY TO WORKMEN
• The Permissible Limits are decided by the imperical formula
keeping in view the tolerable dose of the current through
the human body.
• The injury from the Electric Current is a factor, which is
influenced by so many parameters, current time duration,
voltage, individual reflex action capacity, weight of human
body, etc. As such, it is very much complex phenomena.
• The safety standards are based on the maximum of all such
parameters connected to human body. We have
categorised the Electrical/ Mechanical Accidents in relation
to the electrical equipments.
• In Generating Station, we will focus our study on following
types, which are predominant.
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13. ACCIDENTS IN SUB-STATION
1. Ground potential rise.
2. Touch potential.
3. Step potential.
4. Bursting of oil filled equipment.
5. Potential rise at fencing.
6. Potential rise at non-current carrying parts inside Sub-
station, such as G.I. pipes.
7. Supply to Isolated Equipments due to energising through
another alternative source. (while men at repairs.)
8. Back feeding
9. Fire/ Gas hazard in cable galleries.
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14. MAIN REASONS OF FATAL ACCIDENTS
IN SUB-STATION
1. Improper maintenance, no preventive
maintenance.
2. No proper permit system.
3. Wrong operation of Isolating Switches by
operators.
4. Improper operation of protection devices.
5. Improper Earthing-design.
6. Improper rupturing capacity of equipments.
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15. ELECTRICAL ACCIDENTS IN
GENERATING STATION (Study)
• Temporary installation during construction & repairs work:
• Majority of the Fatal Electrical Accidents occur in Generating Stations due to 230
Volts Electric Supply lines, which are laid Temporarily for Lighting/ Power during
Construction period.
• The lives lost are of Construction Labors. During the inquiry, it is seen that the
attitude of the Owner of Line and the Principle Owner i.e. Power Station persons is
very casual. Everyone stands away from the responsibility & measures the life in
the monitory compensation. This is really incorrect, and against the ethics of
Electrical Engineering.
• It is accepted that the Temporary Installation is necessary, but there are means to
do it very safely. The rules provides the obligation on the Principal Employer or the
Power Station in-charge to see that all such works are done in utmost safe manner,
and are maintained also. Both, comment the breach of Indian Electricity Rules. The
person from Power Station can not escape the charge of willful negligence leading
to the accidents. An Officer must put an effort to that direction, so as to prove that
he has exerted sufficiently and reasonably, but the situation was beyond the
control due to natural forces.
• Use of E.L.C.B. and honour of provisions of Indian Electricity Rules would definitely
stop the accidents in future.
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16. Fire in cable galleries
• In Thermal Power stations, the Cable Galleries attract
the Coal dust & any Arcing i.e. Earth Fault/Puncture
may lead to Explosion.
• Instance have occurred, where such explosion leads to
loss of millions of rupees and cumulative loss due to
withdrawal of Generators from Grid. During Inspection,
It has been pointed out that the Cable installation is
not properly looked.
• There may be other reason in practice. However, as a
Executive, we have to adopt the modern & superior
methods by which the Installation can be maintained in
very much safe manner.
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17. Deficiencies……..
Following are the deficiencies found in installation of
cable galleries.
1. Accumulation of Coal dust in Cable racks.
2. Improper ventilation.
3. Inadequate lighting & Access for routine periodical
inspection.
4. Seepage water in Cable Trenches.
5. Heating of particular cable runs due to loose
connections/overloading/ sparking at Armoring.
6. Improper / inefficient Earth Connection to Armor.
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18. Damage to breakers & transformers
• Many cases of accident are reported due to damage to H.V. / E.H.V.
Breakers & Transformers.
• In most of the cases, there are internal faults, which occur instantly by
weakening of di-electric parameters of the equipment. Many times the
periodical record of Tests are not compared, and if compared the
tolerance of the Officer may be due to threat of running down the
plant, aggravates the situation, and becomes the cause of the accident.
• Taking Tests and comparing with the standards is the real missionary
job, which is to be done with open mind and zeal, and with the study
of International Standard.
• It is also seen that the manufacturing companies many times derate
the Insulation Standard for the major Government Organisations for
the reasons best known to all that how the same equipment, when
supplied to private industries hold very high insulation qualities &
values.
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19. Avoiding inter-locks & wrong
operation of equipments
• In some cases accidents were reported in Power
Station Yard due to operation of isolators on
Load.
• It is prescribed by law that the isolators be
Electrically inter-locked with breakers in such a
way that it is operated only on no-load.
• Sub-station incharge has willfully breached this
provision & caused an accident.
• Proper training to the operating persons should
be given, so as to avoid the misconcept.
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20. Deteriorated earth mats
• In the Generating Station or Sub-station Earth Mat is designed with a
definite fault level, where more parallel connections, from various
sources are brought. Naturally the Fault current level, which is adopted
at the initial level becomes inadequate to take care of all faults. In this
way, the general damage is caused due to high ground potential rise.
• Sometimes the protection cables are damaged due to excessive stress
on insulation and sparking occurs at the armoured end at the end
boxes thus destroying the control. At times, this has compelled to shut
down the Generating Station.
• For the human Safety of Operators in yard, the top surface, which is of
Road metal, has to be necessarily dry to increase the foot resistance of
human body.
• The switchyard, if full of Seepage Water, may detoriate the Grid and
endanger the life of human being. Necessary effective Storm Water
Drain at 60 cm below the Ground level should be done to avoid danger
to human life and property.
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21. Mental loading of maintenance
officers
And Analysis of Faults.
• It is seen that many of the Technical Officers are
loaded beyond the tolerable limit, and they do
not get sufficient time to analyse the situation,
read the data & compare with the standard to
make the effective maintenance periodically.
• The Analysis of Faults should be computerised,
and centrally published, so as to make it available
for staff of all Generating Stations and take
corrective measures.
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22. HOW TO ACHIEVE THE OBJECTIVES OF
COMPLETE SAFETY
• Only the accident prevention can not serve the
process for safety Engineering.
• Reliability Engineering and Safety Engineering go
hand in hand.
• Once, we emphasize on the reliability, most of
the situations, which cause hazards are
eliminated barring personal mistakes. Awareness
of Safety and constant straining or constant
thrust of Safety Thoughts on the mind of
Technicians make possible to avoid any isolated
situation causing hazard.
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23. HOW TO ACHIEVE THE OBJECTIVES OF
COMPLETE SAFETY
• Reliability measurements are a necessary part of
Power System studies, in order to achieve an
acceptable level of reliability at a reasonable cost,
tools have been developed, choosing the most
effective technique, we will be able to determine
the quality of power system.
• Once, this is achieved successfully, the safety
aspect of about 90% is already covered. It is
necessary that all may strive for the reliability &
safety, as a combined aspect of safety hence forth
to achieve long sustaining quality results.
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