Download - 0100 Db 0902
Data Bulletin 0100DB0902R04/1104/2011
Replaces 0100DB0902, 07/2009
Guide to Low Voltage Transformer Protection and Selective CoordinationRetain for future use.
© 2011 Schneider Electric All Rights Reserved ™
Introduction Use this guide for selecting transformer primary circuit breaker, secondary circuit breaker and the largest branch circuit breakers for total selective coordination. The circuit breaker selections conform to the NEC Article 450 requirements for transformer protection while providing total selectivity for the circuits.
See How to Use this Guide, on page 2, for additional information.
Use the Guidelines below for tips on working through systems for selective coordination.
NOTE: It is still necessary to perform an engineering study to determine the specific requirements of each system.
Guidelines
Know your state and municipal code Understand your state and local municipality’s adoption and enforcement regarding the National Electrical Code (NEC). Part of understanding local code adoption and enforcement is understanding the threshold of selective coordination required—0.1s (TCCs) or total, for the full operating range of the protective devices (which typically uses look-up tables). This guide assumes total selective coordination is required.
Lighting Panelboard Recommendations • Do not feed lighting panelboards from other lighting panelboards unless there is a transformer in between them.
• Better levels of selective coordination are available with 225 A and larger panelboards.
• Consider using main lugs panelboards.
Bottom-Up Coordination When selectively coordinating a system, work from the loads towards the source(s), coordinate the branch panels first, then the power distribution panels, then the switchboard or switchgear.
Sizing Upstream Circuit Breakers • The upstream circuit breaker should be at least one frame size larger than the downstream circuit breaker. This may necessitate increasing the size of panelboards and feeder conductors.
• Very high levels of short circuit selective coordination may be achieved by using high ampere frame electronic trip circuit breakers with low ampere sensors and/or lower ampere rating adjustments.
Overlapping Time Current Curves (TCCs) • When there is no overlap (at any point) of the TCCs below the available short circuit current at the downstream panel, the circuit breakers are fully coordinated.
• When there is overlap in the short circuit zone, use the short circuit selective coordination tables in document number 0100DB0501, “Short Circuit Selective Coordination for Low Voltage Circuit Breakers” or
Guide to Low Voltage Transformer Protection and Selective Coordination 0100DB0902R04/11Data Bulletin 04/2011
© 2011 Schneider Electric All Rights Reserved2
document number 0100DB0604, “Selectivity Guidelines for Square D Panelboards”.
Automatic Transfer Switch (ATS) Withstand Ratings
Make sure automatic transfer switches have adequate withstand ratings.
• It may be necessary to relocate the switch, or
It may be necessary to increase the size of the switch.
Mixing of Overcurrent Protective Devices (OCPD)
• Time-Current Curves (TCC) may be used so long as the fault current does not exceed the instantaneous trip point of the upstream breaker
• OCPD from different manufacturers or different types cannot be mixed if the fault current is outside of the parameters describe above.
Arc Flash Incident Energy • Consider how selective coordination impacts the arc flash Protective Personnel Equipment (PPE) levels.
• It may be possible to reduce arc flash incident energy with Zone Selective Interlocking (ZSI).
Nesting Time-Current Curves The time-current curve of a thermal magnetic circuit breaker can sometimes be nested underneath the time-current curve of an upstream electronic trip circuit breaker.
Circuit Breaker Withstand Capacity Molded case circuit breakers (UL 489) will perform to the following levels:
• LA/LH MC (Mission Critical) circuit breaker—Selectively coordinate up to 22 kA with 120 V Circuit Breakers (most economical)
• D-Frame MC (Mission Critical) circuit breaker - Selectively coordinate up to 30kA with 120V circuit breakers
• PowerPact PG/PK and RG/RK circuit breakers—Selectively coordinate up to 65 kA with 277 V Circuit Breakers
• Masterpact NW circuit breakers—Selectively coordinate up to 100 kA with larger molded case circuit breakers
• Refer to 0100DB0501 for complete, total selectivity tables.
Field Adjustment Do not neglect to properly adjust circuit breakers in the field as all Square D low voltage circuit breakers are shipped from the factory with all but the ampere-rating switch in the lowest position.
Rarely needed, but as a last resort . . . • Change the Upstream Circuit Breaker Type to an Insulated Case Circuit Breaker or a Low Voltage Power Circuit Breaker
• Reduce the voltage if the desired level of selective coordination cannot be achieved using a 480Y/277 Vac panelboard. Consider feeding a 208Y/120 Vac panelboard through a transformer.
• Split up some of the loads and use multiple smaller transformers—avoid feeding a 100 A/208 V panel from another 208 V panel.
Insert Impedance through longer run of wire or higher impedance transformers or reactors.
How To Use This Guide 1. Determine the available fault current on primary side of transformer and choose the appropriate reference table.
a. 35 kA / 18 kA
b. 65 kA
c. 100 kA
2. Locate the transformer size on far left of chart. Options are available up to 225 kVA.
3. Based on the specification requirement for aluminum or copper transformer windings, read the available circuit breaker combinations for
0100DB0902R04/11 Guide to Low Voltage Transformer Protection and Selective Coordination04/2011 Data Bulletin
© 2011 Schneider Electric All Rights Reserved 3
primary, secondary (main), and branch circuit breakers for a selectively coordinated system.
4. Choose the circuit breaker combination that best suits your system requirements.
a. The primary circuit breaker should be selected as the device feeding the transformer, whether in a panelboard or circuit breaker enclosure.
b. The secondary circuit breaker should be selected as the main breaker in the panelboard downstream of the transformer; or optionally, could be mounted in a circuit breaker enclosure to feed a main lugs only panelboard.
c. The branch circuit breakers are listed to show the maximum size that can be applied to a full selectively coordinated system. Additionally, notation is made to present which style of QO(B) circuit breaker is required based on current rating and number of poles.
5. Reference data bulletin 0100DB0501 if additional circuit breaker selections are required upstream from the primary circuit breaker to complete the system. This data bulletin is a comprehensive resource for selectively coordinated circuit breaker combinations within the same voltage system.
Guide to Low Voltage Transformer Protection and Selective Coordination 0100DB0902R04/11Data Bulletin 04/2011
© 2011 Schneider Electric All Rights Reserved4
Qu
ick
Re
fere
nc
e G
uid
e f
or
Sel
ecti
ve C
oo
rdin
atio
n B
as
ed o
n 3
5 kA
Av
aila
ble
Fa
ult
Cu
rren
t o
n 4
80
Va
c P
rim
ary
Inpu
t Circ
uit B
reak
er
Mai
n C
ircui
t Bre
aker
Bra
nchC
ircui
t Bre
aker
s
Tran
sfor
mer
AB C
D
No
tes
ab
ou
t u
sin
g t
his
Qu
ick
Re
fere
nce
Gu
ide
:
Thi
s ta
ble
is n
ot m
ea
nt
to r
epl
ace
a s
ele
ctiv
e c
oo
rdin
atio
n sy
ste
m s
tudy
. Th
e p
urp
ose
of
this
gui
de
is f
or
act
iviti
es
tha
t occ
ur b
efo
re t
he f
inal
sy
ste
m s
tud
y, s
uch
as
quo
tatio
n a
nd
itera
tive
de
sign
ch
ang
es,
to
incr
eas
e th
e c
ha
nce
of d
evi
ce c
omb
ina
tions
bei
ng
sel
ect
ivel
y co
ord
ina
ted.
The
de
vice
com
bin
atio
ns p
rese
nte
d in
this
gu
ide
re
pre
sen
t a
leve
l of
"to
tal"
sel
ect
ive
co
ord
ina
tion,
wh
ere
th
e d
evi
ces
we
re c
ho
sen
ba
sed
onth
e m
axim
um le
t-th
rou
gh
cu
rre
nt.
NE
C r
eq
uire
me
nts
fo
r tr
an
sfo
rme
r p
rote
ctio
n w
ere
als
o fo
llow
ed
in th
e s
ele
ctio
n o
f th
e d
evi
ce c
om
bin
atio
ns.
Tra
nsf
orm
ers
are
480
V p
rim
ary
with
20
8Y
/12
0V
se
con
dar
y.
Ta
ble
1:S
elec
tive
Co
ord
inat
ion
Dev
ice
Co
mb
inat
ion
s (
35
kA
)
Prim
ary
Circ
uit B
reak
erS
econ
dary
Circ
uit B
reak
er
Bra
nch
Circ
uit B
reak
ers
for
Tot
al S
elec
tive
Coo
rdin
atio
nT
CC
s
Long
Tim
eS
hort
Tim
eLo
ng
Tim
e
Tra
ns-
form
er
Siz
ekV
A
Gen
eral
P
urpo
se
Tra
nsfo
rmer
T
ype
Tra
nsf
orm
er
Cat
alo
g N
umbe
rs
Min
. Im
peda
nce
(%
Z)1
Circ
uit
Bre
aker
F
ram
e
Fra
me
Siz
e /
Rat
ing
A
Am
pere
R
atin
g2
AS
ettin
gD
elay
Set
ting
Del
ayIn
stan
t-an
eous
Circ
uit
Bre
aker
T
ype
(Mai
n)
Fra
me
Siz
e /
Rat
ing
Min
. S
ettin
gsM
in.
Del
ay
Am
pere
R
atin
g2
(A)
Ma
x.
Bra
nch
Siz
e5
(A)
1P1
5–70
A
2P15
–100
A
2P11
0–15
0A
3P15
–150
A
15A
lum
inum
EE
15T
3H4.
8E
G12
535
––
––
–H
D15
0–
–60
30
QO
(B)
QO
(B)
QO
(B)
001
Cop
per
EE
15T
3HC
U4.
6E
G12
535
––
––
–D
-MC
600/
150
(0.5
)(0.
8)8
603
0Q
O(B
)Q
O(B
)–
QO
(B)
005
(No
te a
)
30
Alu
min
umE
E3
0T3H
5.0
EG
125
80–
––
––
D-M
C60
0/15
0(0
.7)(
0.95
)4
100–
125
50
QO
(B)
QO
(B)
–Q
O(B
)0
02(N
ote
b)
EE
30T
3H5.
0H
G15
080
––
––
–D
-MC
600/
150
(0.7
)(0.
95)
410
0–12
55
0Q
O(B
)Q
O(B
)–
QO
(B)
002
(No
te b
)
Cop
per
EE
30T
3HC
U5.
0E
G12
580
––
––
–D
-MC
600/
150
(0.7
)(0.
95)
410
0–12
55
0Q
O(B
)Q
O(B
)–
QO
(B)
006
(No
te b
)
EE
30T
3HC
U5.
0H
G15
080
––
––
–D
-MC
600/
150
(0.7
)(0.
95)
410
0–12
55
0Q
O(B
)Q
O(B
)–
QO
(B)
006
(No
te b
)
45A
lum
inum
EE
45T
3H5.
2D
G60
0/15
010
0(0
.7)(
0.95
)4
70.
29
D-M
C60
0/15
060
0/25
0(0
.9)(
0.93
)(0
.5)(
1)4
125–
150
125–
175
60
QO
(B)
QO
(B)
–Q
O(B
)0
03
Cop
per
EE
45T
3HC
U4.
3D
G60
0/25
010
0(0
.5)(
0.8)
47
0.2
9D
-MC
600/
150
600/
250
(0.9
)(0.
93)
(0.5
)(1)
412
5–15
012
5–17
56
0Q
O(B
)Q
O(B
)–
QO
(B)
007
75
Alu
min
umE
E7
5T3H
3.5
LA/L
H M
C40
020
0–
––
––
D-M
C60
0/25
060
0/40
0(0
.9)(
1)(0
.7)(
0.8)
1622
5–25
022
5–30
010
0Q
O(B
)Q
O(B
)–
QO
(B)
004
(No
te b
)
EE
75T
3H3.
5LA
/LH
MC
400
200
––
––
–LA
-MC
400
––
225–
250
100
QO
(B)
QO
(B)3
–Q
O(B
)40
04(N
ote
b)
Cop
per
EE
75T
3HC
U3.
4LA
/LH
MC
400
200
––
––
–D
-MC
600/
250
600/
400
(0.9
)(1)
(0.7
)(0.
8)16
225–
250
225–
300
100
QO
(B)
QO
(B)
–Q
O(B
)0
08(N
ote
b)
EE
75T
3HC
U3.
4LA
/LH
MC
400
200
––
––
–LA
-MC
400
––
225–
250
100
QO
(B)
QO
(B)3
–Q
O(B
)40
08(N
ote
b)
112.
5A
lum
inum
EE
112
T3H
5.1
LA/L
H M
C40
020
0–
––
––
D-M
C60
0/40
0(0
.8)(
0.95
)16
300–
400
150
QO
(B)-
VH
QO
(B)-
VH
QO
(B)-
VH
QO
(B)-
VH
010
Cop
per
EE
112T
3HC
U5.
4LA
/LH
MC
400
200
––
––
–D
-MC
600/
400
(0.8
)(0.
95)
1630
0–40
015
0Q
O(B
)-V
HQ
O(B
)-V
HQ
O(B
)-V
HQ
O(B
)-V
H0
13
150
Alu
min
umE
E1
50T
3H5.
9LA
/LH
MC
400
200
––
––
–LA
-MC
400
––
400
100
QO
(B)-
VH
QO
(B)-
VH
–Q
O(B
)0
15(N
ote
b)
EE
150
T3H
5.9
LA/L
H M
C40
020
0–
––
––
D-M
C60
0/60
0(0
.7)(
0.95
)4
400–
600
150
QO
(B)-
VH
QO
(B)-
VH
QO
(B)-
VH
QO
(B)-
VH
015
(No
te b
)C
oppe
rE
E15
0T3C
U5.
4LA
/LH
MC
400
200
––
––
–D
-MC
600/
600
(0.7
)(0.
95)
440
0–60
015
0Q
O(B
)-V
HQ
O(B
)-V
HQ
O(B
)-V
HQ
O(B
)-V
H0
17
225
Alu
min
umE
E2
25T
3H6.
5LA
/LH
MC
400
250
––
––
–D
-MC
600/
600
(1)(
1)4
600
150
QO
(B)-
VH
QO
(B)-
VH
QO
(B)-
VH
QO
(B)-
VH
016
Cop
per
EE
225T
3HC
U3.
7P
G12
00/4
0032
00.
84
100.
2-IN
OF
FD
-MC
600/
600
(1)(
1)4
600
150
QO
(B)-
VH
QO
(B)-
VH
QO
(B)-
VH
QO
(B)-
VH
018
TC
C N
otes
:a.
TC
C s
how
s ov
erla
p be
twe
en th
e se
cond
ary
D-M
C a
nd th
e br
anch
circ
uit b
rea
ker
abov
e th
e in
stan
tane
ous
trip
.b.
Use
d S
KM
"F
unct
ion"
feat
ure
to s
how
two
diff
eren
t prim
ary
circ
uit
brea
ker
choi
ces
on
sam
e T
CC
.1 V
alu
es r
epre
sent
ativ
e of
impe
danc
e va
lues
for
Squ
are
D tr
ansf
orm
ers.
2 A
llow
prim
ary
trip
rat
ing
to in
crea
se to
250
% o
f rat
ed F
LC
(N
EC
450
.4);
se
cond
ary
mai
n tr
ip r
atin
g ca
nnot
exc
eed
125%
of
rate
d F
LC.
3 S
ele
ctiv
e w
ith 2
po
le Q
O(B
) th
roug
h 80
A r
atin
g.4 S
ele
ctiv
e w
ith 3
po
le Q
O(B
) th
roug
h 60
A r
atin
g.5 B
ranc
h ci
rcui
t bre
ake
rs w
ith a
mpe
re r
atin
gs o
f 50%
, or
less
, of t
he D
-MC
ma
in c
ircui
t bre
aker
are
sel
ectiv
e. V
alu
es s
how
n in
thi
s co
lum
n co
rres
pond
to th
e m
inim
um D
-MC
trip
in c
olum
n to
the
left.
AB
CD
Guide to Low Voltage Transformer Protection and Selective Coordination 0100DB0902R04/11Data Bulletin 04/2011
© 2011 Schneider Electric All Rights Reserved5
Qu
ick
Ref
ere
nce
Gu
ide
for
Se
lect
ive
Co
ord
ina
tio
n B
ase
d o
n 6
5 k
A A
vail
ab
le F
ault
Cu
rre
nt
on
480
Va
c P
rim
ary
Inpu
t Circ
uit B
reak
er
Mai
n C
ircui
t Bre
aker
Bra
nchC
ircui
t Bre
aker
s
Tran
sfor
mer
AB C
D
No
tes
abo
ut
usi
ng
th
is Q
uic
k R
efer
ence
Gu
ide:
Th
is ta
ble
is n
ot
me
ant
to r
ep
lace
a s
ele
ctiv
e c
oord
ina
tion
sys
tem
stu
dy.
Th
e pu
rpo
se o
f th
is g
uid
e is
fo
r a
ctiv
itie
s th
at
occ
ur b
efo
re t
he
fina
l sy
ste
m s
tud
y, s
uch
as
qu
ota
tion
an
d it
era
tive
de
sig
n ch
ang
es,
to in
cre
ase
the
cha
nce
of
devi
ce c
om
bin
atio
ns
be
ing
se
lect
ive
ly c
oo
rdin
ate
d.
Th
e d
evic
e co
mb
ina
tion
s p
rese
nte
d in
th
is g
uid
e r
ep
rese
nt a
leve
l of
"to
tal"
se
lect
ive
coo
rdin
atio
n,
whe
re th
e d
evi
ces
wer
e c
hose
n b
ase
d o
nth
e m
axi
mu
m le
t-th
roug
h c
urr
ent
.
NE
C r
equ
irem
en
ts fo
r tr
an
sfor
me
r p
rote
ctio
n w
ere
als
o fo
llow
ed in
the
sele
ctio
n of
the
de
vice
co
mbi
na
tion
s.
Tra
nsf
orm
ers
are
48
0V
pri
ma
ry w
ith 2
08
Y/1
20V
sec
ond
ary
.
Tab
le2:
Sel
ecti
ve C
oo
rdin
ati
on
Dev
ice
Co
mb
inat
ion
s (6
5 kA
)
Prim
ary
Circ
uit B
reak
erS
econ
dar
y C
ircui
t Bre
aker
Bra
nch
Circ
uit B
reak
ers
for
Tot
al S
elec
tive
Co
ordi
natio
nT
CC
s
Lon
g T
ime
Sho
rt T
ime
Long
Tim
e
Tra
ns-
form
er
Siz
ekV
A
Gen
eral
P
urpo
se
Tra
nsfo
rmer
T
ype
Tra
nsfo
rmer
C
atal
og
Num
bers
Min
. Im
peda
nce
(% Z
)1
Circ
uit
Bre
aker
F
ram
e
Fra
me
Siz
e /
Rat
ing
A
Am
pere
R
atin
g2
AS
ettin
gD
elay
Set
ting
De
lay
Inst
ant-
aneo
us
Circ
uit
Bre
aker
T
ype
(Mai
n)
Fra
me
Siz
e /
Rat
ing
Min
. S
ettin
gsM
in.
Del
ay
Am
pere
R
atin
g2
(A)
Max
. B
ranc
h S
ize5
(A)
1P15
–70
A
2P15
–100
A
2P11
0–1
50A
3P15
–150
A
15A
lum
inum
EE
15T
3H4.
8E
J1
2535
––
––
–H
D15
0–
–60
30Q
O(B
)Q
O(B
)Q
O(B
)02
1
Cop
per
EE
15T
3HC
U4.
6E
J1
2535
––
––
–D
-MC
600/
150
(0.5
)(0.
8)8
6030
QO
(B)
QO
(B)
–Q
O(B
)02
5(N
ote
a)
30
Alu
min
umE
E30
T3H
5.0
EJ
125
80–
––
––
D-M
C60
0/15
0(0
.7)(
0.95
)4
100–
125
50Q
O(B
)Q
O(B
)–
QO
(B)
022
(Not
e b
)
EE
30T
3H5.
0H
J1
5080
––
––
–D
-MC
600/
150
(0.7
)(0.
95)
410
0–12
550
QO
(B)
QO
(B)
–Q
O(B
)02
2(N
ote
b)
Cop
per
EE
30T
3HC
U5.
0E
J1
2580
––
––
–D
-MC
600/
150
(0.7
)(0.
95)
410
0–12
550
QO
(B)
QO
(B)
–Q
O(B
)02
6(N
ote
b)
EE
30T
3HC
U5.
0H
J1
5080
––
––
–D
-MC
600/
150
(0.7
)(0.
95)
410
0–12
550
QO
(B)
QO
(B)
–Q
O(B
)02
6(N
ote
b)
45A
lum
inum
EE
45T
3H5.
2D
J60
0/1
5010
0(0
.7)(
0.95
)8
70
.29
D-M
C60
0/15
060
0/25
0(0
.9)(
0.93
)(0
.5)(
1)4
125–
150
125–
175
60Q
O(B
)Q
O(B
)–
QO
(B)
023
Cop
per
EE
45T
3HC
U4.
3D
J60
0/2
5010
0(0
.5)(
0.8)
87
0.2
9D
-MC
600/
150
600/
250
(0.9
)(0.
93)
(0.5
)(1)
412
5–15
012
5–17
560
QO
(B)
QO
(B)
–Q
O(B
)02
7
75
Alu
min
umE
E75
T3H
3.5
DJ
600
/400
160
(0.5
)(0.
8)8
70
.29
D-M
C60
0/25
0(0
.9)(
1)16
225–
300
100
QO
(B)
QO
(B)
–Q
O(B
)02
4(N
ote
b)
EE
75T
3H3.
5D
J60
0/4
0016
0(0
.5)(
0.8)
87
0.2
9LA
-MC
400
––
225–
250
100
QO
(B)
QO
(B)3
–Q
O(B
)402
4(N
ote
b)
Cop
per
EE
75T
3HC
U3.
4D
J60
0/4
0016
0(0
.5)(
0.8)
87
0.2
9D
-MC
600/
250
600/
400
(0.9
)(1)
(0.7
)(0.
8)16
225–
250
225–
300
100
QO
(B)
QO
(B)
–Q
O(B
)02
8(N
ote
b)
EE
75T
3HC
U3.
4D
J60
0/4
0016
0(0
.5)(
0.8)
87
0.2
9LA
-MC
400
––
225–
250
100
QO
(B)
QO
(B)3
–Q
O(B
)402
8(N
ote
b)
112
.5A
lum
inum
EE
112T
3H5.
1D
J60
0/4
0020
0(0
.5)(
1)8
70
.29
D-M
C60
0/40
0(0
.8)(
0.95
)16
300–
400
150
QO
(B)-
VH
QO
(B)-
VH
QO
(B)-
VH
QO
(B)-
VH
030
Cop
per
EE
112T
3HC
U5.
4D
J60
0/4
0020
0(0
.5)(
1)8
70
.29
D-M
C60
0/40
0(0
.8)(
0.95
)16
300–
400
150
QO
(B)-
VH
QO
(B)-
VH
QO
(B)-
VH
QO
(B)-
VH
033
150
Alu
min
umE
E15
0T3H
5.9
DJ
600
/600
240
(0.5
)(0.
8)8
70
.29
D-M
C60
0/60
0(0
.7)(
0.95
)4
400–
600
150
QO
(B)-
VH
QO
(B)-
VH
QO
(B)-
VH
QO
(B)-
VH
031
Cop
per
EE
150T
3CU
5.4
DJ
600
/600
240
(0.5
)(0.
8)8
70
.39
D-M
C60
0/60
0(0
.7)(
0.95
)4
400–
600
150
QO
(B)-
VH
QO
(B)-
VH
QO
(B)-
VH
QO
(B)-
VH
034
225
Alu
min
umE
E22
5T3H
6.5
PJ
1200
/400
320
0.8
48
0.2
-IN
12D
-MC
600/
600
(1)(
1)4
600
150
QO
(B)-
VH
QO
(B)-
VH
QO
(B)-
VH
QO
(B)-
VH
036
Cop
per
EE
225T
3HC
U3.
7P
J12
00/4
0032
00.
84
80
.2-I
NO
FF
D-M
C60
0/60
0(1
)(1)
460
015
0Q
O(B
)-V
HQ
O(B
)-V
HQ
O(B
)-V
HQ
O(B
)-V
H03
8T
CC
No
tes:
a. T
CC
sho
ws
over
lap
bet
wee
n th
e se
cond
ary
D-M
C a
nd t
he b
ranc
h ci
rcui
t br
eake
r ab
ove
the
inst
anta
neou
s tr
ip.
b.
Use
d S
KM
"F
unct
ion"
feat
ure
to s
how
tw
o di
ffere
nt p
rimar
y ci
rcui
t bre
aker
cho
ices
on
sam
e T
CC
.1 V
alue
s re
pres
enta
tive
of im
peda
nce
valu
es fo
r S
quar
e D
tran
sfor
mer
s.2 A
llow
prim
ary
trip
ra
ting
to in
crea
se to
250
% o
f rat
ed F
LC (
NE
C 4
50.4
); s
econ
dary
ma
in tr
ip r
atin
g ca
nnot
exc
eed
125
% o
f rat
ed F
LC.
3 S
elec
tive
with
2 p
ole
QO
(B)
thro
ugh
80A
rat
ing
.4 S
elec
tive
with
3 p
ole
QO
(B)
thro
ugh
60A
rat
ing
.5 B
ranc
h ci
rcui
t bre
aker
s w
ith a
mpe
re r
atin
gs o
f 50%
, or
less
, of t
he D
-MC
mai
n ci
rcui
t bre
ake
r ar
e se
lect
ive.
V
alue
s sh
own
in t
his
colu
mn
corr
esp
ond
to th
e m
inim
um D
-MC
trip
in c
olum
n to
the
left.
AB
CD
Guide to Low Voltage Transformer Protection and Selective Coordination 0100DB0902R04/11Data Bulletin 04/2011
© 2011 Schneider Electric All Rights Reserved6
Qu
ick
Re
fere
nc
e G
uid
e f
or
Sel
ecti
ve C
oo
rdin
atio
n B
as
ed o
n 1
00 k
A A
vail
able
Fa
ult
Cu
rre
nt
on
48
0 V
ac P
rim
ary
Inpu
t Circ
uit B
reak
er
Mai
n C
ircui
t Bre
aker
Bra
nchC
ircui
t Bre
aker
s
Tran
sfor
mer
AB C
D
No
tes
ab
ou
t u
sin
g t
his
Qu
ick
Re
fere
nce
Gu
ide
:
Thi
s ta
ble
is n
ot m
ea
nt
to r
epl
ace
a s
ele
ctiv
e c
oo
rdin
atio
n sy
ste
m s
tudy
. Th
e p
urp
ose
of
this
gui
de
is f
or
act
iviti
es
tha
t occ
ur b
efo
re t
he f
inal
sy
ste
m s
tud
y, s
uch
as
quo
tatio
n a
nd
itera
tive
de
sign
ch
ang
es,
to
incr
eas
e th
e c
ha
nce
of d
evi
ce c
omb
ina
tions
bei
ng
se
lect
ivel
y co
ord
ina
ted.
The
de
vice
com
bin
atio
ns p
rese
nte
d in
this
gu
ide
re
pre
sen
t a
leve
l of
"to
tal"
sel
ect
ive
co
ord
ina
tion,
wh
ere
th
e d
evi
ces
we
re c
ho
sen
ba
sed
onth
e m
axim
um le
t-th
rou
gh
cu
rre
nt.
NE
C r
eq
uire
me
nts
fo
r tr
an
sfo
rme
r p
rote
ctio
n w
ere
als
o fo
llow
ed
in th
e s
ele
ctio
n o
f th
e d
evi
ce c
om
bin
atio
ns.
Tra
nsf
orm
ers
are
480
V p
rim
ary
with
20
8Y
/12
0V
se
con
dar
y.
Ta
ble
3:S
elec
tive
Co
ord
inat
ion
Dev
ice
Co
mb
inat
ion
s (
100
kA
)
Prim
ary
Circ
uit B
reak
er
Se
cond
ary
Circ
uit B
reak
erB
ranc
h C
ircui
t Bre
aker
s fo
r T
otal
Sel
ect
ive
Coo
rdin
atio
nT
CC
s
Long
Tim
eS
hort
Tim
eLo
ng T
ime
Tra
ns-
form
er
Siz
ekV
A
Gen
eral
P
urpo
se
Tra
nsfo
rmer
T
ype
Tra
nsfo
rmer
C
atal
og
Num
bers
Min
. Im
peda
nce
(% Z
)1
Circ
uit
Bre
aker
F
ram
e
Fra
me
Siz
e /
Rat
ing
A
Am
pere
R
atin
g2
AS
ettin
gD
ela
yS
ettin
gD
elay
Inst
ant-
aneo
us
Circ
uit
Bre
ake
r T
ype
(Mai
n)
Fra
me
Siz
e /
Rat
ing
Plu
g
Min
. S
ettin
gsM
in.
Del
ay
Am
pere
R
atin
g2
(A)
Max
. B
ranc
h S
ize5
(A)
1P1
5–70
A
2P15
–100
A
2P1
10–1
50A
3P15
–150
A
30A
lum
inum
EE
30T
3H5.
0H
L15
080
––
––
–D
-MC
600/
150
(0.7
)(0.
95)
410
0–1
2550
QO
(B)
QO
(B)
–Q
O(B
)04
2C
oppe
rE
E30
T3
H_C
u5.
0H
L15
080
––
––
–D
-MC
600/
150
(0.7
)(0.
95)
410
0–1
2550
QO
(B)
QO
(B)
–Q
O(B
)04
6
45A
lum
inum
EE
45T
3H5.
2D
L60
0/15
010
0(0
.7)(
0.9
5)8
70.
29
D-M
C60
0/15
060
0/25
0(0
.9)(
0.93
)(0
.5)(
1)4
125
–150
125
–175
60Q
O(B
)Q
O(B
)–
QO
(B)
043
Cop
per
EE
45T
3H
_Cu
4.3
DL
600/
250
100
(0.5
)(0
.8)
87
0.2
9D
-MC
600/
150
600/
250
(0.9
)(0.
93)
(0.5
)(1)
412
5–1
5012
5–1
7560
QO
(B)
QO
(B)
–Q
O(B
)04
7
75
Alu
min
umE
E75
T3H
3.5
DL
600/
400
160
(0.5
)(0
.8)
87
0.2
9LA
-MC
400
––
225
–300
100
QO
(B)
QO
(B)3
–Q
O(B
)404
4(N
ote
b)
EE
75T
3H3.
5D
L60
0/40
016
0(0
.5)(
0.8
)8
70.
29
D-M
C60
0/25
060
0/40
0(0
.9)(
1)(0
.7)(
0.8)
1622
5–2
5022
5–3
0010
0Q
O(B
)Q
O(B
)–
QO
(B)
044
(Not
e b)
Cop
per
EE
75T
3H
_Cu
3.4
DL
600/
400
160
(0.5
)(0
.8)
87
0.2
9LA
-MC
400
––
225
–300
100
QO
(B)
QO
(B)3
–Q
O(B
)404
8(N
ote
b)
EE
75T
3H
_Cu
3.4
DL
600/
400
160
(0.5
)(0
.8)
87
0.2
9D
-MC
600/
250
600/
400
(0.9
)(1)
(0.7
)(0.
8)16
225
–250
225
–300
100
QO
(B)
QO
(B)
–Q
O(B
)04
8(N
ote
b)
112.
5A
lum
inum
EE
112
T3H
5.1
DL
600/
400
200
(0.5
)(1)
87
0.2
9D
-MC
600/
400
(0.8
)(0.
95)
1630
0–4
0015
0Q
O(B
)-V
HQ
O(B
)-V
HQ
O(B
)-V
HQ
O(B
)-V
H05
0C
oppe
rE
E11
2T3
H_C
u5.
4D
L60
0/40
020
0(0
.5)(
1)8
70.
29
D-M
C60
0/40
0(0
.8)(
0.95
)16
300
–400
150
QO
(B)-
VH
QO
(B)-
VH
QO
(B)-
VH
QO
(B)-
VH
053
150
Alu
min
umE
E15
0T
3H5.
9D
L60
0/60
024
0(0
.5)(
0.8
)8
70.
29
D-M
C60
0/60
0(0
.7)(
0.95
)4
400
–600
150
QO
(B)-
VH
QO
(B)-
VH
QO
(B)-
VH
QO
(B)-
VH
051
Cop
per
EE
150T
3_C
u5.
4D
L60
0/60
024
0(0
.5)(
0.8
)8
70.
39
D-M
C60
0/60
0(0
.7)(
0.95
)4
400
–600
150
QO
(B)-
VH
QO
(B)-
VH
QO
(B)-
VH
QO
(B)-
VH
054
225
Alu
min
umE
E22
5T
3H6.
5P
L12
00/4
0032
00.
84
80.
2-IN
12D
-MC
600/
600
(1)(
1)4
600
150
QO
(B)-
VH
QO
(B)-
VH
QO
(B)-
VH
QO
(B)-
VH
056
Cop
per
EE
225T
3H
_Cu
3.7
PL
1200
/400
320
0.8
48
0.2-
INO
FF
D-M
C60
0/60
0(1
)(1)
46
0015
0Q
O(B
)-V
HQ
O(B
)-V
HQ
O(B
)-V
HQ
O(B
)-V
H05
8T
CC
Not
es:
a. T
CC
sho
ws
ove
rlap
betw
een
the
seco
ndar
y D
-MC
and
the
bran
ch c
ircui
t bre
aker
abo
ve th
e in
stan
tane
ous
trip
.b.
Use
d S
KM
"F
unct
ion"
feat
ure
to s
how
two
diffe
ren
t prim
ary
circ
uit b
rea
ker
choi
ces
on s
am
e T
CC
.1 V
alu
es r
epre
sent
ativ
e of
impe
danc
e va
lues
for
Squ
are
D tr
ansf
orm
ers.
2 A
llow
prim
ary
trip
rat
ing
to in
crea
se to
250
% o
f rat
ed F
LC
(N
EC
450
.4);
se
cond
ary
mai
n tr
ip r
atin
g ca
nnot
exc
eed
125%
of
rate
d F
LC.
3 S
ele
ctiv
e w
ith 2
po
le Q
O(B
) th
roug
h 80
A r
atin
g.4 S
ele
ctiv
e w
ith 3
po
le Q
O(B
) th
roug
h 60
A r
atin
g.5 B
ranc
h ci
rcui
t bre
ake
rs w
ith a
mpe
re r
atin
gs o
f 50%
, or
less
, of t
he D
-MC
ma
in c
ircui
t bre
aker
are
sel
ectiv
e. V
alu
es s
how
n in
thi
s co
lum
n co
rres
pond
to th
e m
inim
um D
-MC
trip
in c
olum
n to
the
left.
AB
CD
0100DB0902R04/11 Guide to Low Voltage Transformer Protection and Selective Coordination04/2011 Data Bulletin
© 2011 Schneider Electric All Rights Reserved 7
Guide to Low Voltage Transformer Protection and Selective Coordination 0100DB0902R04/11Data Bulletin 04/2011
© 2011 Schneider Electric All Rights Reserved8
0100DB0902R04/11 Guide to Low Voltage Transformer Protection and Selective Coordination04/2011 Data Bulletin
© 2011 Schneider Electric All Rights Reserved 9
Guide to Low Voltage Transformer Protection and Selective Coordination 0100DB0902R04/11Data Bulletin 04/2011
© 2011 Schneider Electric All Rights Reserved10
0100DB0902R04/11 Guide to Low Voltage Transformer Protection and Selective Coordination04/2011 Data Bulletin
© 2011 Schneider Electric All Rights Reserved 11
Guide to Low Voltage Transformer Protection and Selective Coordination 0100DB0902R04/11Data Bulletin 04/2011
© 2011 Schneider Electric All Rights Reserved12
0100DB0902R04/11 Guide to Low Voltage Transformer Protection and Selective Coordination04/2011 Data Bulletin
© 2011 Schneider Electric All Rights Reserved 13
Guide to Low Voltage Transformer Protection and Selective Coordination 0100DB0902R04/11Data Bulletin 04/2011
© 2011 Schneider Electric All Rights Reserved14
0100DB0902R04/11 Guide to Low Voltage Transformer Protection and Selective Coordination04/2011 Data Bulletin
© 2011 Schneider Electric All Rights Reserved 15
Guide to Low Voltage Transformer Protection and Selective Coordination 0100DB0902R04/11Data Bulletin 04/2011
© 2011 Schneider Electric All Rights Reserved16
0100DB0902R04/11 Guide to Low Voltage Transformer Protection and Selective Coordination04/2011 Data Bulletin
© 2011 Schneider Electric All Rights Reserved 17
Guide to Low Voltage Transformer Protection and Selective Coordination 0100DB0902R04/11Data Bulletin 04/2011
© 2011 Schneider Electric All Rights Reserved18
0100DB0902R04/11 Guide to Low Voltage Transformer Protection and Selective Coordination04/2011 Data Bulletin
© 2011 Schneider Electric All Rights Reserved 19
Guide to Low Voltage Transformer Protection and Selective Coordination 0100DB0902R04/11Data Bulletin 04/2011
© 2011 Schneider Electric All Rights Reserved20
0100DB0902R04/11 Guide to Low Voltage Transformer Protection and Selective Coordination04/2011 Data Bulletin
© 2011 Schneider Electric All Rights Reserved 21
Guide to Low Voltage Transformer Protection and Selective Coordination 0100DB0902R04/11Data Bulletin 04/2011
© 2011 Schneider Electric All Rights Reserved22
0100DB0902R04/11 Guide to Low Voltage Transformer Protection and Selective Coordination04/2011 Data Bulletin
© 2011 Schneider Electric All Rights Reserved 23
Guide to Low Voltage Transformer Protection and Selective Coordination 0100DB0902R04/11Data Bulletin 04/2011
© 2011 Schneider Electric All Rights Reserved24
0100DB0902R04/11 Guide to Low Voltage Transformer Protection and Selective Coordination04/2011 Data Bulletin
© 2011 Schneider Electric All Rights Reserved 25
Guide to Low Voltage Transformer Protection and Selective Coordination 0100DB0902R04/11Data Bulletin 04/2011
© 2011 Schneider Electric All Rights Reserved26
0100DB0902R04/11 Guide to Low Voltage Transformer Protection and Selective Coordination04/2011 Data Bulletin
© 2011 Schneider Electric All Rights Reserved 27
Guide to Low Voltage Transformer Protection and Selective Coordination 0100DB0902R04/11Data Bulletin 04/2011
© 2011 Schneider Electric All Rights Reserved28
0100DB0902R04/11 Guide to Low Voltage Transformer Protection and Selective Coordination04/2011 Data Bulletin
© 2011 Schneider Electric All Rights Reserved 29
Guide to Low Voltage Transformer Protection and Selective Coordination 0100DB0902R04/11Data Bulletin 04/2011
© 2011 Schneider Electric All Rights Reserved30
0100DB0902R04/11 Guide to Low Voltage Transformer Protection and Selective Coordination04/2011 Data Bulletin
© 2011 Schneider Electric All Rights Reserved 31
Guide to Low Voltage Transformer Protection and Selective Coordination 0100DB0902R04/11Data Bulletin 04/2011
© 2011 Schneider Electric All Rights Reserved32
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