power u protective relay series bus protection 10-22-18 · differential overcurrent • ct...
Post on 18-Mar-2020
5 Views
Preview:
TRANSCRIPT
By
Mat
t Hor
vath
, P.E
.
Nov
embe
r 6, 2
018
Intr
oduc
tion
to B
us P
rote
ctio
n
Pre
sent
atio
n O
utlin
e1.
Phy
sica
l Bus
Typ
es2.
Typi
cal B
us C
onfig
urat
ions
3.B
us P
rote
ctio
n M
etho
ds &
Sch
emes
4.H
igh
Z B
us D
iffer
entia
l Pro
tect
ion
Afte
r thi
s pr
esen
tatio
n yo
u w
ill b
e ab
le to
:•
Iden
tify
com
mon
bus
arr
ange
men
ts•
Iden
tify
and
unde
rsta
nd th
e op
erat
ion
of c
omm
on b
us
prot
ectio
n sc
hem
es•
Und
erst
and
high
impe
danc
e bu
s di
ffere
ntia
l ope
ratin
g pr
inci
ples
(SE
L-58
7Z)P
urpo
se &
Lea
rnin
g O
bjec
tives
Ele
ctric
al B
uses
PhysicalandElectricalJunctio
n
“Abu
sisa
criticalelemen
tofa
power
system
,asitisthe
pointo
fconvergenceof
manycircuits.”
From
IEEE
Std.C3
7.97
AGu
idefor
ProtectiveRelayAp
plica
tions
toPower
System
Buses
•M
ain
Com
pone
nts
–C
oppe
r or a
lum
inum
con
duct
or–
Sup
porti
ng s
truct
ures
–P
ost I
nsul
ator
s–
Sol
id a
nd/o
r fle
xibl
e co
nnec
tors
•A
dvan
tage
s–
Rel
ativ
ely
Eco
nom
ical
–S
impl
e–
Eas
y to
trou
ble
shoo
t–
Sho
rt re
pair
time
–Lo
nger
Fre
e S
pans
Ope
n A
ir R
igid
Bus
•D
isad
vant
ages
•E
xpos
ure
•La
rger
foot
prin
t req
uire
d
•M
ain
Com
pone
nts
–Fl
exib
le C
ondu
ctor
s–
Sup
porti
ng S
truct
ures
–S
train
insu
lato
rs
•A
dvan
tage
s–
Sm
all f
ootp
rint
–S
impl
icity
–Ve
ry E
cono
mic
al–
Sho
rt re
pair
time
Stra
in B
us
•D
isad
vant
ages
•Lo
wer
relia
bilit
y•
Exp
osur
e•
Con
duct
or s
paci
ng a
nd c
apac
ity
•M
ain
com
pone
nts:
–R
idge
d ce
nter
con
duct
or–
Sup
porti
ng in
sula
tors
–A
ir di
elec
tric
–B
ushi
ngs
at te
rmin
atio
n po
ints
–E
xter
nal s
uppo
rting
stru
ctur
es
•A
dvan
tage
s–
Hig
her r
elia
bilit
y–
Pro
tect
ed–
Sm
alle
r con
duct
or s
paci
ng–
Forc
ed a
ir co
olin
g po
ssib
le
Isol
ated
-Pha
se B
us
•D
isad
vant
ages
•H
igh
cost
•Lo
ngre
pair
time
•E
xpen
sive
•M
ain
com
pone
nts:
–R
idge
d ce
nter
con
duct
or–
Sup
porti
ng in
sula
tors
–In
sula
ting
gas
–B
ushi
ngs
at te
rmin
atio
n po
ints
–E
xter
nal s
uppo
rting
stru
ctur
es
•A
dvan
tage
s–
Hig
her r
elia
bilit
y–
Pro
tect
ed–
Very
sm
all c
orrid
or
Gas
Insu
late
d B
us
•D
isad
vant
ages
•H
igh
cost
•D
iffic
ult t
roub
lesh
ootin
g•
Long
repa
ir tim
e
•M
ain
Com
pone
nts
–A
lum
inum
or c
oppe
r con
duct
or–
Sol
id C
onne
ctor
s–
Sup
porti
ng In
sula
tors
•A
dvan
tage
s–
Vers
atile
–S
mal
l foo
tprin
t–
Pro
tect
ed•
Dis
adva
ntag
es–
Con
fined
spa
ce
Indo
or S
witc
hgea
r Bus
Bus
Fau
lt C
hara
cter
istic
s
•N
ot v
ery
com
mon
Whe
n th
ey d
o oc
cur:
•U
sual
ly b
olte
d fa
ults
•H
ighe
r fau
lt m
agni
tude
s
Bus
Fau
lt Im
pact
:•
All
bus
circ
uits
mus
t be
inte
rrup
ted
•C
an re
sult
in s
ever
e sy
stem
di
stur
banc
es
Impo
rtanc
e of
Bus
P
rote
ctio
n•
Ded
icat
ed p
rote
ctio
n•
Hig
h sp
eed
oper
atio
n fo
r in
tern
al fa
ults
•Tw
o-ou
t-of-t
wo
trip
crite
ria•
Opt
iona
l red
unda
nt p
rote
ctio
n sc
hem
e•
Rem
ote
back
up p
rote
ctio
n•
Tim
e ov
ercu
rrent
pro
tect
ion
•
Sec
urity
for o
ut-o
f-zon
e fa
ults
•S
ensi
tivity
for m
inim
um in
tern
al
faul
ts
Bus
Pro
tect
ion
Phi
loso
phy
Prin
cipl
e an
d O
pera
tion
•Tr
ips
and
lock
outs
the
bus
brea
kers
•M
any
outp
ut c
onta
cts
•O
pera
tion
isol
ates
its
trip
coil
•Ve
ry fa
st o
pera
tion
•H
ardw
ired
to b
reak
er tr
ip
circ
uits
•C
an b
e us
ed to
pro
tect
re
lay
cont
acts
Bus
Loc
kout
Rel
ays
•Im
prov
es s
yste
m re
liabi
lity
•M
inim
izes
Impa
ct o
f Out
ages
•U
tiliz
es V
ario
us A
rrang
emen
ts–
Com
bine
d A
rrang
emen
ts–
Ope
ratin
g Fl
exib
ility
–S
elec
tivity
–B
us p
rote
ctio
n m
ust a
dapt
Bus
Sec
tiona
lizin
g
Diagram
1
Diagram
2
One
of t
he m
ost b
asic
and
ec
onom
ical
des
igns
No
oper
atin
g fle
xibi
lity
No
sele
ctiv
ity
Zone
of P
rote
ctio
n•
Enc
ompa
sses
the
who
le b
us
Bus
faul
t will
inte
rrupt
all
asso
ciat
ed s
ervi
ces
Sin
gle
Bus
–S
ingl
e B
reak
er•
Zone
of P
rote
ctio
n:
–B
us a
nd T
rans
form
er p
rote
ctio
n is
co
mbi
ned
•U
sual
ly u
sed
in d
istri
butio
n su
bsta
tions
•N
o se
lect
ivity
•N
o fle
xibi
lity
•Fa
ult l
ocat
ion
diffi
culty
•Ve
ry e
cono
mic
al
Bus
& T
rans
form
er –
Sin
gle
Bre
aker
Dou
ble
Bus
w/B
us T
ie
–S
ingl
e B
reak
er
•Zo
ne o
f Pro
tect
ion:
•
Bus
A a
nd B
us B
ha
ve in
depe
nden
t an
d de
dica
ted
prot
ectio
n
•Li
ttle
Flex
ibili
ty
•S
ome
Sel
ectiv
ity
Mai
n &
Tra
nsfe
r Bus
–
Sin
gle
Bre
aker
Breakersub
stitu
tion
Zone
ofProtectio
nEncompasses
mainbu
son
ly
Transfer
busp
rotection
provided
bytransfer
breaker
Noselectivity
Flexibilityincreases
Ofte
nCo
mbine
d
Dou
ble
Bus
–S
ingl
e B
reak
er•
Zone
of P
rote
ctio
n:
•B
us 1
and
Bus
2 h
ave
inde
pend
ent
prot
ectio
n as
sign
ed b
ased
on
switc
hing
co
nditi
on
•Lo
ts o
f ope
ratin
g fle
xibi
lity
•S
ome
sele
ctiv
ity
•C
ompl
ex s
witc
hing
•C
T w
indi
ng a
ssig
nmen
ts c
hang
e
•N
ot c
omm
only
use
d in
the
U.S
.
Dou
ble
Bus
–D
oubl
e B
reak
er•
Zone
of P
rote
ctio
n:•
Bus
1 a
nd B
us 2
hav
e in
depe
nden
t pro
tect
ion
•Fu
ll op
erat
ing
flexi
bilit
y
•Im
prov
ed S
elec
tivity
•In
crea
sed
cost
•Ve
ry c
omm
on
Rin
g B
us
•N
o de
dica
ted
bus
prot
ectio
n
•Fu
ll op
erat
ing
flexi
bilit
y
•G
ood
sele
ctiv
ity
•S
hare
d br
eake
rs
•E
cono
mic
al
Bre
aker
-And
-A-H
alf
Bus
•Fu
llop
erat
ing
flexi
bilit
y
•E
xcel
lent
sel
ectiv
ity
•W
idel
y us
ed
•Zo
ne o
f Pro
tect
ion:
•
Bus
A a
nd B
us B
hav
e in
depe
nden
t an
d de
dica
ted
prot
ectio
n zo
nes.
•Li
ne p
ositi
on p
rote
ctio
n pr
ovid
ed b
y br
anch
circ
uits
•E
cono
mic
al
Diff
eren
tial O
verc
urre
nt
•C
T se
cond
ary
lead
s su
mm
ed o
ut s
ide
the
rela
y
•Id
entic
al T
ap ra
tios
•C
T m
atch
ing
•D
iffer
ence
Cur
rent
usi
ng
51/5
0 el
emen
ts
•Ti
me
dela
yed
•Av
oid
mis
oper
atio
ndu
e to
tra
nsie
nt s
atur
atio
n
Adv
anta
ges
•E
cono
mic
al
Dis
adva
ntag
es•
Sec
urity
•S
trong
sou
rces
•Ti
me-
dela
yed
clea
ring
•D
iffic
ult t
o se
t pro
perly
•N
ot s
uita
ble
in a
reas
of s
yste
m
with
hig
h X
/R ra
tio
Diff
eren
tial O
verc
urre
nt
(con
tinue
d)
Par
tial B
us D
iffer
entia
l
Ope
ratin
g P
rinci
ples
:
•S
ourc
e C
T le
ads
sum
med
ou
tsid
e re
lay
•Ti
e br
eake
r CTs
incl
uded
•O
verc
urre
nt e
lem
ent
•P
icku
p se
t abo
ve lo
ad
•S
elec
tivity
requ
ired
•O
ptio
nal:
Dis
tanc
e el
emen
ts
Par
tial B
us D
iffer
entia
l (C
ontin
ued)
Par
tial B
us D
iffer
entia
l (C
ontin
ued)
Adv
anta
ges:
•
Very
eco
nom
ical
Dis
adva
ntag
es:
•Fa
ult C
urre
nt/F
LA•
Req
uire
d se
lect
ivity
•R
educ
ed s
ensi
tivity
•U
sed
with
radi
al
circ
uits
Zone
Inte
rlock
Sch
eme
(Fas
t Bus
Trip
ping
)O
pera
ting
Prin
cipl
e: (A
nim
atio
n)•
Sou
rce
circ
uit(s
) •
Tim
e de
laye
d •
Rec
eive
s/S
ends
Blo
ck
Sig
nal
•D
irect
iona
lity
•R
adia
l circ
uit(s
)•
Inst
anta
neou
s el
emen
t se
nds
bloc
k si
gnal
•C
omm
unic
atio
n
Zone
Inte
rlock
Sch
eme
(Con
tinue
d)
Adv
anta
ges:
•Fa
st c
ompa
red
to in
vers
e-tim
e O
C e
lem
ents
•R
elat
ivel
y ec
onom
ical
Dis
adva
ntag
es:
•R
equi
res
Com
mun
icat
ion
Sch
eme
•S
ecur
ity a
gain
st C
T S
atur
atio
n•
Slo
wer
than
hig
h-Z
or p
erce
ntag
e-re
stra
int
sche
mes
Dire
ctio
nal C
ompa
rison
Ope
ratin
g P
rinci
ple:
•D
ista
nce
Ele
men
ts
Adv
anta
ges
•R
elat
ivel
y E
cono
mic
al•
Few
CT
cons
train
ts
Dis
adva
ntag
es•
Volta
ge R
efer
ence
•M
ultip
le F
ailu
re P
oint
s
Hig
h C
urre
nt
Inte
rrup
tion
& L
imiti
ngFu
ses
& S
hort
Circ
uit L
imite
rs•
Hig
h In
terr
upt r
atin
g•
IS li
mite
r ope
rate
s in
less
th
an 1
ms
Adv
anta
ges
•E
xtre
mel
y H
igh
Spe
ed
Dis
adva
ntag
es•
Rep
lace
men
ts n
eede
d w
ith fu
sibl
e in
terr
upte
rs
Arc
Fla
sh P
rote
ctio
n
Opt
ical
Sen
sors
•Fi
ber o
ptic
sen
sors
or l
oops
•In
door
Sw
itchg
ear
Adv
anta
ges
•R
elat
ivel
y E
cono
mic
al•
Ext
rem
ely
Hig
h S
peed
Dis
adva
ntag
es•
Sup
ervi
sion
with
opt
ical
Per
cent
age
Res
train
ed
Diff
eren
tial
Ope
ratin
g P
rinci
ple:
(Ani
mat
ion)
•R
elay
mea
sure
s di
ffere
nce
and
rest
rain
t qua
ntiti
es•
Trip
if d
iffer
ence
cur
rent
exc
eeds
a s
et p
erce
ntag
e of
the
rest
rain
ing
quan
tity
TieBK
RN.O.
I01C
FI02C
FI01
I02
BKR2
N.C.
BKR1
N.C.
Per
cent
age
Res
train
ed
Diff
eren
tial (
Con
tinue
d)
•O
pera
te v
s. R
estra
int R
elat
ions
hip
•S
lope
Set
ting
•C
ontro
lling
Fac
tors
•C
T P
erfo
rman
ce•
X/R
Rat
io•
Faul
t Mag
nitu
de
•D
uel S
lop
Cha
ract
eris
tic
Per
cent
age
Res
train
ed
Diff
eren
tial (
Con
tinue
d)
Per
cent
age
Res
train
ed
Diff
eren
tial (
Con
tinue
d)P
erce
ntag
e R
estra
ined
D
iffer
entia
l (C
ontin
ued)
CT4Cu
rren
ts:
Per
cent
age
Res
train
ed
Diff
eren
tial (
Con
tinue
d)
•Re
layconstantlymon
itors
changesinop
erateand
restraintcurrents
•Increase
inrestraint
with
outa
nincrease
inop
eratecurren
tind
icates
externalfault
•Re
layentershigh
securitymod
e
•Onlyrequ
iress
hortpe
riod
(~24m
s)of
unsaturated
operation
Per
cent
age
Res
train
ed
Diff
eren
tial (
Con
tinue
d)
Settings
Considerations
•Minim
umpickup
mustb
egreaterthanerrord
ifferen
cecurrent,
butlessthanminim
umavailablefaultcurrent
•Typically
setto1p
uof
busc
ontin
uous
ratin
gon
solid
grou
nded
system
s•
Lower
pickup
susedon
impe
dancegrou
nded
system
s
•Slop
esettings
•With
standmeasuremen
terrorsa
tlow
curren
ts•
With
standsaturatio
nindu
cederrorsat
high
curren
ts
•Mod
ernrelays
with
adaptivean
slope
characteristic
provide
enhanced
securityandsensitivity
Per
cent
age
Res
train
ed
Diff
eren
tial (
Con
tinue
d)
Adv
anta
ges:
•Fa
st O
pera
tion
•G
ood
secu
rity
Dis
adva
ntag
es:
•C
T cr
iteria
and
pe
rform
ance
crit
ical
•M
ay re
quire
man
y re
lay
curr
ent i
nput
s
•S
ensi
tivity
—H
igh
Z G
roun
ded
Sys
tem
s
IOP=|I1+I2|
IRST
=|I1|
+|I2|
Hig
h Im
peda
nce
Bus
(V
olta
ge) D
iffer
entia
l In
trodu
ctio
n an
d B
asic
Con
cept
(Ani
mat
ion)
•P
opul
ar B
us P
rote
ctio
n S
chem
e•
Arc
Fla
sh M
itiga
tion
Vsmall
Vbig
Hig
h Im
peda
nce
Bus
D
iffer
entia
l (C
ontin
ued)
•CTsc
onne
cted
inparallelw
ithhigh
impe
dancerelayinpu
t
•Re
layop
erates
onvolta
geacross
high
impe
danceinpu
ts
•Ca
naccommod
atealarge
numbe
rofterminals
•Excellent
sensitivity
and
speed
•Simpleelem
enttoconfigure
Characteristicsa
ndTypicalA
pplicationLayout
Hig
h Im
peda
nce
Bus
D
iffer
entia
l (C
ontin
ued)
ExternalFault(or
typicalloa
ding)C
ase:
•Cu
rren
tcirculates
betw
eenCTs
•Negligiblecurren
tflowthroughhigh
impe
dancerelayinpu
t(high
resistance/bu
rden
path)
Hig
h Im
peda
nce
Bus
D
iffer
entia
l (C
ontin
ued)
Worst
Case
ExternalFault:
•CT
2completelysaturates(do
esno
tsup
plyanyrepresentativesecond
arycurren
twaveform)
•High
impe
danceinpu
tseesv
oltage
develope
dby
second
arycurren
tflowingthrough
CTwinding
resistanceandlead
resistance
•Elem
entp
ickupmustb
esetg
reater
than
thisvolta
ge(typicallyby
afactor
of1.5to
2)forsecurity
Hig
h Im
peda
nce
Bus
D
iffer
entia
l (C
ontin
ued)
InternalFaultC
ase:
•Cu
rren
tflowsthrou
ghstabilizin
gresistora
ndprod
uces
high
second
aryvolta
ges
•Vo
ltage
magnitude
limite
dby
MOV
•LO
R‘a’con
tactsreq
uiredacrosshigh
impe
danceinpu
t
•CTsp
rodu
cecurren
tand
second
aryvolta
geun
tilthey
saturate
Hig
h Im
peda
nce
Bus
D
iffer
entia
l (C
ontin
ued)
•S
tabi
lizin
g re
sist
or
•M
OV
pro
tect
s el
emen
t
•B
us L
OR
requ
ired
Hig
h Im
peda
nce
Bus
D
iffer
entia
l (C
ontin
ued)
•S
EL
587Z
Rel
ay•
Use
s a
2000
resi
stor
•M
OV
siz
e op
tions
•S
EL
Rec
omm
ende
d S
ettin
gs (P
er A
N20
08-0
1)•
Vs
setti
ng o
f 200
V•
Opt
iona
l Tim
e D
elay
ed S
ettin
g
Hig
h Im
peda
nce
Bus
D
iffer
entia
l (C
ontin
ued)
Man
ufac
ture
r Int
erna
l Fau
lt Te
stin
g•
Test
cur
rent
s of
20
kA, 4
0 kA
and
60
kA a
pplie
d.•
Hea
vy C
T sa
tura
tion
obse
rved
Hig
h Im
peda
nce
Bus
D
iffer
entia
l (C
ontin
ued)
Wav
efor
ms
obta
ined
from
man
ufac
ture
r tes
ting
•D
iffer
entia
l cur
rent
and
vol
tage
wav
efor
ms
•N
ote
the
volta
ge is
lim
ited
to 1
500V
by
the
inte
rnal
MO
V•
C20
0 12
00:5
CTs
, 60
kA in
tern
al fa
ult
Hig
h Im
peda
nce
Bus
D
iffer
entia
l (C
ontin
ued)
60 k
A In
tern
al F
ault
Test
1. C
T Vo
ltage
(Gre
en)
2. T
otal
Cur
rent
(Blu
e)3.
Exc
itatio
n C
urre
nt (R
ed)
•R
esis
tor v
s. M
agne
tizin
g C
urre
nt
•Th
e vo
lt-tim
e ar
ea
C40
0
Hig
h Im
peda
nce
Bus
D
iffer
entia
l (C
ontin
ued)
C10
0
Volttim
earea
prop
ortio
naltoCratin
g
Dictated
bylowestratedCT
indiffe
rentialcircuit
SELrecommen
dsat
leasta
C200
CT
Hig
h Im
peda
nce
Bus
D
iffer
entia
l (C
ontin
ued)
Vo
lttim
earea
issim
ilarfor
CTsw
itheq
uivalent
Cratin
g,even
ifratio
sare
diffe
rent
Maxim
umvolta
gelim
itedby
MOV
Man
ufac
ture
r Ext
erna
l Fau
lt Te
stin
g R
esul
ts
•Fa
ult c
urre
nts
of 2
0 kA
, 40
kA a
nd 6
0 kA
.
Hig
h Im
peda
nce
Bus
D
iffer
entia
l (C
ontin
ued)
MO
V S
izin
g fo
r SE
L-58
7Z•
MO
V re
quire
men
ts b
ased
on
ene
rgy
diss
ipat
ion
limits
for
4-cy
cle
dura
tion
•Re
quire
s86“a”
contactswire
dacross
relayinpu
ts!
•E
nerg
y ra
ting
is a
func
tion
of k
nee-
poin
t vol
tage
and
m
axim
um s
econ
dary
cu
rren
t
Hig
h Im
peda
nce
Bus
D
iffer
entia
l (C
ontin
ued)
H
igh
Impe
danc
e B
us
Diff
eren
tial (
Con
tinue
d)
Man
ufac
ture
r Tes
ting
Res
ults
for S
EL-
587Z
Rec
omm
ende
d H
igh-
Valu
e S
ettin
g:•
200V
with
no
time
dela
y•
Sen
sitiv
e an
d S
ecur
e
Opt
iona
l Rec
omm
enda
tions
For
Low
-Val
ue S
ettin
g:•
Onl
y ne
eded
in s
ome
appl
icat
ions
(e.g
. HR
G/L
RG
)•
Min
imum
sen
sitiv
ity c
alcu
latio
ns•
Impl
emen
t a ti
me
dela
y (m
in 1
cyc
le).
Hig
h Im
peda
nce
Bus
D
iffer
entia
l (C
ontin
ued)
Sec
ure
Volta
ge S
ettin
g C
alcu
latio
n
•S
ensi
tivity
impa
cted
by
wiri
ng d
esig
n
•W
orst
-cas
e ou
t-of-z
one
faul
t con
ditio
n
•R
elay
pic
kup
set t
o a
mul
tiple
of V
r
Hig
h Im
peda
nce
Bus
D
iffer
entia
l (C
ontin
ued)
Min
imum
Sen
sitiv
ity C
alcu
latio
n•
Verif
y fo
r Int
erna
l Fau
lt•
Igno
re M
OV
leak
age
curr
ent
•U
se C
T E
xcita
tion
Cha
ract
eris
tic•
Whe
n V
s <
knee
poi
nt v
olta
ge:
•W
hen
Vs
> kn
ee p
oint
vol
tage
:
Hig
h Im
peda
nce
Bus
D
iffer
entia
l (C
oncl
usio
n)
Advantages:
•Very
fastop
eration
•High
security
•Incorporates
largenu
mbe
rof
term
inals
Disadvantages:
•Sensitivity
decreasesa
snum
bero
fCTsa
nd/orleadlengthsincreases
•Mustu
seCTsw
ithC2
00ratin
gor
greater
•Co
mplexities
associated
with
mixed
ratio
CTs
•B
us p
rote
ctio
n is
crit
ical
•B
us S
ectio
naliz
ing
–O
pera
ting
flexi
bilit
y–
Sel
ectiv
ity
•B
us P
rote
ctio
n S
chem
es–
Wid
e va
riety
of s
chem
es
avai
labl
e ba
sed
on a
pplic
atio
n•
Crit
ical
ity•
Avai
labl
e fa
ult c
urre
nt &
X/R
ratio
•S
ensi
tivity
/Spe
ed R
equi
rem
ents
•C
T av
aila
bilit
y
Sum
mar
y
•IE
EE
Std
. C37
.97,
Gui
de fo
r Pro
tect
ive
Rel
ay A
pplic
atio
ns to
Pow
er B
uses
•B
lack
burn
, J. L
ewis
, Pro
tect
ive
Rel
ayin
g, P
rinci
ples
and
App
licat
ions
, Thi
rd
Edi
tion,
New
Yor
k: M
arce
l Dek
ker,
1998
•B
asle
r Ele
ctric
Com
pany
, Bus
Pro
tect
ive
Rel
ayin
g, M
etho
ds a
nd
App
licat
ion,
Rev
isio
n D
ate:
6-8
-200
5
•G
ener
al E
lect
ric C
ompa
ny, B
us D
iffer
entia
l Pro
tect
ion,
WP
RC
199
5, G
ER
-39
61
•Zo
chol
l, E
. Sta
nley
and
Cos
tello
, Dav
id, S
chw
eitz
er E
ngin
eerin
g La
bora
torie
s, In
c., A
pplic
atio
n G
uide
lines
for M
icro
proc
esso
r-Bas
ed, H
igh-
Impe
danc
e B
us D
iffer
entia
l Rel
ays
•C
oste
llo, D
avid
and
Moo
ney,
Joe
, App
lyin
g th
e S
EL-
587Z
in S
witc
hgea
r, S
EL
App
licat
ion
Not
e A
N20
08-0
1
Ref
eren
ces
Than
k yo
u fo
r you
r tim
e!Th
is c
oncl
udes
the
educ
atio
nal c
onte
nt o
f thi
s ac
tivity
.
Mat
t Hor
vath
, P.E
.
Elec
tric
al E
ngin
eer
(509
) 780
-004
2
mat
t.Hor
vath
@po
wer
ing.
com
top related