How we saved a Generator (in fact two), again!

1.
Backgr
Finding
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‐
How
round
t was j
received a
urgently, t
along with
On enquir
12 MW, 1
taken on
industry,
warranted
Hearing th
checklist (
we find th
upcoming
We imme
by the firs
up and wo
gs‐ at Site
The initial
that the R
normally
such fault
like last lin
So, such a
extra vigi
protection
I
we sav
ust anothe
a call from
they wante
h its relayin
ring about
11 kV got
rental ba
Generator
d extensiv
his, the da
(we’ll see
he Root Ca
g repaired G
diately dis
st flight ava
orking.
l forensics
Relay (and
a time de
t occurs (st
ne of defen
a surprising
lant. This
n system.
ved a G
er day and
m a new C
ed us to te
ng, scheme
such urge
burnt (sta
sis and a
r failure is
ve and me
ay went int
it later in a
use and so
Generator
patched 2
ailable and
were fou
d GCB eve
layed prot
tator failur
nse.
g observat
warranted
Generat
d another
Customer i
est and com
es and com
ency, we le
ator) and w
temporary
nothing le
ethodical a
to a tizzy a
a diagram)
olve it, this
too!
of our eng
d were soo
nd from th
ntually) w
tection. It
re), other
tion just at
d us for i
Authorised
tor (in f
morning o
n Metal Se
mmission a
mplete test
earnt that
was sent f
y solution
ess than a
analysis li
and we im
) to find o
rented Ge
gineers alo
on on the jo
he fault re
was tripped
was a sur
protection
t the start
n‐depth a
d Channel
fact tw
of January
ector, from
n old 10 M
ing.
their origi
for repairin
. As we a
an air‐cras
ke an air‐
mmediately
ut the Roo
enerator w
ong with th
ob. In less
ecords of t
d on NPS
prise, beca
ns take car
of the job
nd thorou
Partners
wo), aga
2019, on
m Chhattis
MW, 11 kV
inal Gener
ng, this 10
all know th
h and this
‐crash inve
y started p
ot Cause. A
was in dang
he test sets
than a day
the Relay.
protection
ause norm
re, NPS is s
b prompte
ugh checki
ain!
which we
sgarh. And
Generator
ator rated
0 MW was
hat in our
s criticality
estigation.
reparing a
And unless
er and the
s required,
y, we were
We learnt
n, which is
mally when
something
d us to be
ing of the
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e

2.
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‐
And then
wiring wa
Protection
Fault sche
Following
Protection
Generator
eventually
operated,
Seen here
came the
as the culp
n Engineer
eme checki
actual im
n (51S) did
r kept run
y, NPS op
the dama
e is S2 miss
Stator B
e moment
prit for the
r so to spe
ing).
mages clea
not opera
ning on th
peration o
ge was alre
sing (to Re
Burnt
t of recko
e Generat
eak (It wa
arly show
ate due to n
his serious
operated o
eady done
elay)
Authorised
ning, and
or burn‐ou
s found w
the fault.
non‐wiring
a fault wh
on time d
.
Co
d Channel
you know
ut! Least e
while carryi
So, 90 %
g of NCT se
hich finally
delay. But
orrected by
Disconne
Partners
w from wh
expected f
ing out St
% Stator E
econdary S2
y led to he
t by the
y new wirin
ected Wind
here? NCT
fault for a
ator Earth
arth Fault
2 to Relay.
eating and
time NPS
ng
ding
T
a
h
t
.
d
S

3. ‐
‐
‐
‐
‐
‐
‐
NCT, whic
But from
case of St
relevant b
wire.
Differentia
settings w
compiled
ordination
Suppose b
operate a
these are
this case,
because in
Reverse P
Logic was
With the
changing t
Similarly,
Frequency
set logic
imagine!
LBB Prote
Manual o
other des
wiring.
Following
ch is used f
TB to Rela
tator E/F,
breakers. T
al Protecti
was not a
during com
n, Power Sy
both the a
nd genera
Class A pr
it’s AVR.
nter‐panel
Power and
s so wrong
set logic,
the logic.
this wro
y and Ove
didn’t let
Corrected
ection trip
f the Gene
signated fu
Diagram w
for Stator E
ay, wire S2
Relay wou
This fault w
ion setting
available, w
mmissionin
ystem and
bove prote
te alarm a
rotection a
And you
wiring wa
Forward P
gly set tha
, these pr
ng logic
r Frequen
these pro
by changin
ping was
erator Prot
unctions a
will help us
E/F Protect
2 was miss
uldn’t hav
was simply
g was foun
we recom
ng and to
Load Flow
ections, St
and trip sig
and must c
know wha
s not done
Power Pro
t neither A
rotections
error was
cy Protect
otections g
ng the logi
assigned
tection Re
nd not thi
s understan
Authorised
tion, was w
sing/not co
e sensed
y corrected
nd high, b
mended t
carry out t
w.
ator E/F a
gnals faithf
cut the ve
at we foun
e. Correcte
otections w
Alarm cou
were ren
s observe
ions. All th
generate a
c.
to Output
elay, this O
is. Correct
nd this crit
d Channel
wired up to
onnected o
nor opera
d by conne
besides, th
to furnish
the fresh S
nd Differe
fully. And a
ry source
nd? AVR c
d and now
were set b
ld be gene
ndered us
ed in Und
hese were
any Alarm
t No. 3, b
Output No.
ted by cha
ical event
Partners
o TB in CRP
on Relay. S
ted nor tr
ecting a 2.
he referenc
us the O
Studies on
ntial, are a
as we all k
of the fau
ould not b
w stands re
ut with wr
erated nor
eless. Cor
der Voltag
e set alrigh
or Trippin
but as per
3 must be
anging the
better.
P correctly.
So even in
ripped the
5 sq. mm.
ce for the
OEM data,
Relay Co‐
alright and
now, both
lt. Here in
be tripped
ctified.
rong logic.
r Tripping!
rrected by
ge, Under
ht, but the
ng signals,
the OEM
e used for
logic and
.
n
e
.
e
,
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d
h
n
d
.
y
r
e
,
r

4. Authorised Channel Partners

5. Conclu
‐
‐
‐
‐
‐
usion – How
Not only o
the protec
And gene
now onwa
By doing
will be pu
rewinding
Generator
continuou
our effort
in totality
affects th
And that’s
And at la
difference
The above
our very
abnormal
to us, we’
And if yo
between
anywhere
w our insig
our team v
ctions ava
erate a cor
ards, the w
so, we als
t in place a
g data but m
r is an e
usly runnin
ts are view
. Testing, a
e end‐resu
s what we
st, we we
e between
e are in fa
busy 3‐da
ities and c
ll be happy
u’re lookin
your asset
e.
ghtful actio
verified tha
ilable, they
rrect tripp
way a safe a
o ensured
after due r
more or les
expensive
g plant du
wing the pr
as such, is
ults (produ
delivered.
ere happy
symptom‐
ct the maj
ys (and n
orrected a
y to save y
ng for a d
ts and you
ons helped
at the new
y verified
ing sequen
and reliabl
complete
repairs. Set
ss, the mac
asset itse
ue to failure
roblems fro
an isolated
uction/rev
to “wow”
‐solving‐ag
jor problem
ights too)
as many as
our assets
edicated a
ur revenue
Authorised
d the Indus
wly installe
that it ope
nce too. N
e protectio
e protectio
ttings need
chine will b
elf, and t
e of a Gen
om custom
d job, but w
enue), the
” the custo
gents and p
ms found a
at site, w
possible. W
too!
agency wh
e, we’ll be
d Channel
stry
ed Generat
erates, and
No burning
on system
on of 12 M
d to be ver
be protecte
the loss o
nerator can
mers’ point
when it is
en it’s pro
omer, who
proper Doc
and correc
we also ob
Well, to kn
ho underst
happy to
Partners
tor of 10 M
d operates
g of Gener
should be.
MW Genera
rified/corre
ed.
of produc
n run in to
t and resol
done in a w
foundly m
o learnt a
ctors.
cted. Thou
bserved ma
now more,
tands the
assist you
MW has all
s correctly.
rator from
.
ator which
ected with
ction in a
crores. All
lving them
way which
meaningful.
t last, the
gh, during
any minor
, call/write
direct link
, anytime,
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