LPS study for water treatment plant

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LABUGAMA
&
KALATUWAWA
WATER
TREATMENT
PLANT
LIGHTNING
STUDY
(RISK
ASSESSMENT)
REPORT
ON
LIGHTNING
PROTECTION
1. Introduction
Lightning
protection
study
is
a
highly
site
specific,
with
many
design
unique
to
individual
facilities
and
structures.
Mitigation
of
the
effects
of
lightning
strike
is
attempted
through
the
deployment
of
a
combination
of
exterior
and
interior
defenses.
The
dangerous
effects
of
strikes
to
automated
water
treatment
plants
can
include
damage
in
sophisticated
electronic
equipment
and
life
loss.
There
are
no
devices
and
methods
capable
of
preventing
for
lightning
discharges.
The
type
of
damage
depends
on
the
position
of
the
point
of
the
strike,
on
its
characteristic
and
systems
involved.
The
occurrences,
which
are
caused
by
lightning,
can
threat
people,
critical
structures,
internal
electrical
and
electronic
systems
due
to
electromagnetic
effects
of
lightning
current,
so
that
the
selection
of
adequate
protection
measures
has
a
high
priority.
2. Objectives
The
objective
of
this
lightning
protection
study
is
to;
• Review
the
existing
lightning
protection
system
against
national
and
international
standards.
• Risk
assessment
to
the
site
to
identify
required
protection
level.
3. Standards
This
document
refers
to
the
following
standards:
• EN
62305-­‐1:
"Protection
against
lightning.
Part
1:
General
principles";
• EN
62305-­‐2:
"Protection
against
lightning.
Part
2:
Risk
assessment";
• EN
62305-­‐3:
"Protection
against
lightning.
Part
3:
Physical
damage
to
structures
and
life
hazards";
• EN
62305-­‐4:
"Protection
against
lightning.
Part
4:
Electrical
and
electronic
systems
within
structures";
4. Parameters
of
lightning
current
The
most
important
parameters
for
the
purpose
of
designing
protection
systems
are
peak
value
of
the
stroke
and
the
lighting
density
of
the
area.
In
both
case
of
Labugama
and
Kalatuwawa
the
isokeraounic
level
is
well
above
100
and
nearly
114
days
(fig:01).
The
peak
current
is
at
average
of
36kA.
[The
data
is
from
“Activity
of
cloud-­‐to-­‐ground
lightning
observed
in
Sri
Lanka
and
in
surrounding
area
of
the
Indian
Ocean”
by
A.
B.
Weerasekera,
D.
U.
J.
Sonnadara,
I.
M.
K.
Fernando,
J.P.
Liyanage,
R.
Lelwala
and
T.
R.
Ariyaratne]

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Fig
01:
Isokeraounic
Map
Sri
Lanka
[The
map
is
based
on
the
findings
of
the
study
“Lightning
conditions
in
Ceylon,
and
measures
to
reduce
damage
to
electrical
equipment”
by
Dr
Gi-­‐ichi
Ikeda
in
1968
(Asian
Productivity
organization
report,
May
1969
–
AP)
Project
TES/68)]
5. Risks
of
lightning
strikes
Since
this
Labugama
and
Kaltuwawa
are
the
main
water
treatment
plants,
which
deliver
water
to
Sri
Lankas’
capital
city,
Colombo,
and
breakdown
of
the
plants
due
to
event
like
lightning
cannot
be
underestimated.
For
the
purposes
of
lightning
protection
to
automated
water
treatment
plants
may
be
classified
as
“critical
structures”
due
to
the
very
heavy
consequential
effects
of
lightning
flash,
which
can
cause
damage
to
the
structure
and
affect
to
lot
of
people
benefited
by
the
treatment
plant.
Cloud-­‐to-­‐ground
lightning
strokes
present
a
clear
and
immediate
danger
for
ground
personnel
involved
in
outdoor
operations.
When
this
danger
presents,
people
outside
operations
are
suspended
until
the
threat
has
passed.
Direct
and
nearby
cloud-­‐to-­‐ground
discharges
can
be
hazardous
to
structures,
persons,
installations
and
other
systems
within
or
on
structures.
So,
the
application
of
lightning
protection
measures
must
be
considered.
The
decision
for
the
need
for
protection
and
the

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selection
of
protection
measures
should
be
determined
in
terms
of
risk;
it
means
that
these
measures
should
be
adequate
to
reduce
the
risk
to
a
tolerable
level.
The
modern
approach
is
that
of
risk
management
which
integrates
the
need
for
protection
and
the
selection
of
adequate
protection
measures
taking
into
account
the
efficiency
of
the
measures.
In
the
risk
management
approach,
the
lightning
threats
that
create
risk
are
identified,
the
frequencies
of
all
risk
events
are
estimated,
the
consequences
of
the
risk
events
are
determined
and,
if
these
are
above
a
tolerable
level
of
risk,
protection
measures
are
applied
to
reduce
the
risk
(R)
to
below
the
tolerable
level
(RT).
The
criteria
for
design,
installation
and
maintenance
of
lightning
protection
measures
may
be
distinguished
as
protection
measures
to
reduce
mechanical
damages,
fire,
explosion
danger
and
life
hazard
due
to
direct
lightning
flashes
to
the
structure;
protection
measures
against
the
electromagnetic
effects
of
lightning
on
electrical
and
electronic
systems
within
a
structure;
protection
measure
to
reduce
the
loss
of
services
entering
the
structure,
power,
telecommunication
and
data
lines.
It
should
be
stressed
that
the
selection
of
adequate
protection
measures
aim
to
reduce
not
only
the
risk
by
direct
flashes
to
the
structure
but
even
the
risk
for
low-­‐
voltage
and
electronic
systems
against
indirect
flashes,
it
means
the
risk
due
to
flashes
to
ground
near
the
structure,
flashes
direct
to
the
lines
or
flashes
to
ground
near
the
lines
entering
the
plant.
6. Review
of
Existing
LPS
Kalatuwawa
The
existing
water
treatment
plant
at
Kalatuwawa
located
in
a
congested
area
beneath
the
tank
bund.
Along
side
of
the
outdoor
water
sedimentation
area
a
chemical
dosage
and
equipment
room
is
situated.
The
outdoors
water
sedimentation
area
has
metal
structures
for
maintenance
works
and
they
are
not
been
equipotentially
bonded
to
earth.
The
plant
room
is
comprised
with
generators,
turbines,
electrical
panel
boards,
motors,
etc.
this
plant
room
is
protected
by
external
lightning
protection
systems
(LPS)
comprise
of
few
air
finials,
roof
conductors
and
earthing
arrangements
complied
to
BS
6651.
No
electronic
systems
are
used
in
controlling
the
plant
room.
Annexure
01
contains
all
the
measurements
taken
for
the
external
existing
LPS
for
its
condition.
No
surge
protection
has
been
used
to
protect
the
power
panels
and
electrical
equipment.
Site
earth
and
continuity
testing
was
carried
out
using
Fluke
multifunction
tester
mode
1653B.
However,
a
metal
roof
is
designed
to
cover
the
existing
outdoor
pant
area
with
the
new
renovations
and
the
plant
room
is
modernized
with
new
equipment
with
electronics
incorporated
for
automated
operations.
Further
a
new
control
building
is
proposed
adjacent
to
the
plant
room
and
a
store
building
is
being
renovated.
New
power
supply
is
proposed
to
the
site
by
upgrading
the
existing
transformer.

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Fig
02:
Plan
of
treatment
plant
at
Kalatuwawa
taken
from
the
top
of
the
tank
bund.
Labugama
This
is
mostly
an
indoor
type
water
treatment
pant
but
there
is
an
out
door
plant
area
at
the
beginning
of
the
treatment
process.
This
site
is
located
beneath
the
Labugama
tank
bund
along
side
the
entrance
road
(which
is
at
roof
level
of
the
plant
room)
to
the
tank
bund.
This
gives
a
natural
protection
to
part
of
the
building.
The
outdoor
plant
area
is
not
bonded
to
earth
and
comprised
with
metal
walkways.
This
plant
room
is
protected
by
external
lightning
protection
systems
(LPS)
comprise
of
few
air
finials,
roof
conductors
and
earthing
arrangements
complied
with
BS
6651.
No
electronic
systems
are
used
in
controlling
the
plant
room.
Annexure
02
contains
all
the
measurements
taken
for
the
external
existing
LPS
for
its
condition.
The
tank
bund
the
fuel
station
and
some
structures
along
the
entrance
road
are
protected
with
isolated
LPS.
No
surge
protection
has
been
used
to
protect
the
power
panels
and
electrical
equipment.
Fig
03:
Plan
of
treatment
plant
at
Labugama
taken
from
the
top
of
the
tank
bund.

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There
are
few
other
buildings
coming
up
for
the
chemical
dosage,
generator,
etc.
The
plant
room
roof
is
being
repaired.
The
complex
electronics
and
power
room
is
coming
under
this
plant
room.
New
power
supply
is
proposed
to
the
site
by
upgrading
the
existing
transformer.
7. Risk
analysis
and
Recommendations
The
risk
analysis
was
done
to
both
sites
covering
all
the
structures
of
the
plants.
The
annexure
03
and
04
contains
the
risk
analysis
done
as
per
the
BS
EN
62305
part
2.
The
result
and
required
protection
level
is
also
discussed
and
the
recommendations
were
made
case
by
case
and
are
included
in
the
above
annexures.
Annexure
03
conversed
the
risk
assessment
and
recommendations
for
Kalatuwawa
site
and
Annexure
04
is
for
Labugama
site.
It
is
generally
observed
from
the
results
that
there
is
no
risk
in
direct
hit
of
lightning
to
the
considered
structures.
However
coordinated
SPD
protection
is
required.
8. Conclusions
A
LPS
shall
be
designed
in
accordance
with
BS
EN
62305
parts
3
and
4
based
on
these
recommendations
discussed
under
the
annexures
related
to
chapter
7
to
reduce
the
risk
level
to
a
tolerable
value.
This
LPS
shall
be
implement
to
mitigate
the
lightning
effects
to
the
site
and
thereby
minimizes
the
risk
of
failure
of
the
plants.
Basnayaka
D.S.K.
Director
B.Sc.
(Eng),
C.
Eng,
M.Sc.
(Power),
MIESL,
APGBCSL