Siemens SB04TLI Owner's manual

SIEMENS
Electronic
Trip
Unit
for
SB
Encased
Systems
Breakers
Information
and
Instruction
Guide
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Courtesy of NationalSwitchgear.com

A
DANGER
h
Hazardous
voltages
are
present
inside
the
enclo
-
sures
or
panels
in
which
the
circuit
breakers
are
installed
.
Serious
injury
,
electrocution
,
and
/
or
equip
-
ment
damage
will
result
if
circuit
breakers
are
improperly
applied
or
precaution
is
not
used
.
De
-
energize
all
incoming
power
prior
to
installation
of
circuit
breakers
or
associated
accessories
.
Only
qualified
personnel
should
work
on
or
around
this
equipment
.
Position
of
circuit
breaker
indicators
shown
in
this
booklet
is
for
illustration
pur
-
poses
only
.
Circuit
breakers
are
to
be
installed
in
Off
or
Tripped
position
only
.
IMPORTANT
The
information
contained
herein
is
general
in
nature
and
not
intended
for
specific
application
purposes
.
It
does
not
relieve
the
user
of
responsibility
to
use
sound
practices
in
application
,
installation
,
operation
,
and
maintenance
of
the
equipment
purchased
.
Siemens
reserves
the
right
to
make
changes
in
the
specifications
shown
herein
or
to
make
improvements
at
any
time
without
notice
or
obligations
.
Should
a
conflict
arise
between
the
general
information
contained
in
this
publication
and
the
contents
of
drawings
or
supplementary
material
or
both
,
the
latter
shall
take
precedence
.
NOTE
‘
Authorized
and
qualified
personnel
—
For
the
purpose
of
this
manual
a
qualified
person
is
one
who
is
familiar
with
the
installation
,
construction
or
operation
of
the
equipment
and
the
hazards
involved
.
In
addition
,
he
has
the
following
qualifications
:
(
a
)
is
trained
and
authorized
to
de
-
energize
,
clear
,
ground
,
and
tag
circuits
and
equipment
in
accordance
with
established
safety
practices
.
(
b
)
is
trained
in
the
proper
care
and
use
of
protective
equipment
such
as
rubber
gloves
,
hard
hat
,
safety
glasses
or
face
shields
,
flash
clothing
,
etc
.
,
in
accordance
with
established
safety
practices
.
(
c
)
is
trained
in
rendering
first
aid
.
SUMMARY
These
instructions
do
not
purport
to
cover
all
details
or
variations
in
equip
-
ment
,
nor
to
provide
for
every
possible
contingency
to
be
met
in
connection
with
installation
,
operation
,
or
maintenance
.
Should
further
information
be
desired
or
should
particular
problems
arise
which
are
not
covered
sufficiently
for
the
purchaser
’
s
purposes
,
the
matter
should
be
referred
to
the
local
sales
office
,
listed
on
back
of
this
instruction
guide
.
The
contents
of
this
instruction
manual
should
not
become
part
of
or
modify
any
prior
or
existing
agreement
,
commitment
or
relationship
.
The
sales
contract
contains
the
entire
obligation
of
Siemens
Energy
&
Automation
,
Inc
.
The
warranty
contained
in
the
contract
between
the
parties
is
the
sole
warranty
of
Siemens
Energy
&
Automation
,
Inc
.
Any
statements
contained
herein
do
not
create
new
warranties
or
modify
the
existing
warranty
.
Courtesy of NationalSwitchgear.com

Electronic
Trip
Unit
for
Siemens
Type
SB
Systems
Breakers
Table
of
Contents
Ground
Fault
Sensing
Schemes
Example
Time
Current
Curve
(
2000
A
)
Standard
Test
and
Monitoring
Functions
System
Check
Indicator
Trip
Status
Indicator
Lights
Integral
Test
Modes
Optional
Functions
Display
Module
(
Current
Monitoring
)
Zone
Selective
Interlocking
Communications
(
Remote
Monitoring
)
18
inside
cover
Important
Notices
19
Information
and
Instructions
20
Electronic
Trip
Unit
Overcurrent
Protection
Configurations
RMS
Current
Sensing
Systems
Breaker
Frame
Sizes
Systems
Breaker
Frame
Ampere
Ratings
Rating
Plugs
Principles
of
Operation
Functional
Diagram
20
2
2
20
20
3
21
3
21
3
3
21
21
4
5
Time
Current
Characteristic
Curves
22
-
34
Installation
Instructions
Installing
the
Trip
Unit
Removing
the
Trip
Unit
Accessories
6
-
8
Auxiliary
Power
Module
and
Display
Module
Universal
Test
Kit
(
TS
-
31
)
35
9
36
-
37
Operations
Removing
/
Replacing
Plexiglass
Cover
Inserting
and
Removing
the
Rating
Plug
Electronic
Trip
Unit
Functions
Setting
the
Fault
Protection
Adjustments
Current
Shaping
Fault
Protection
Adjustments
Long
Time
Fault
Protection
Short
Time
Fault
Protection
Ordering
and
Catalog
Information
Electronic
Trip
Unit
10
-
11
38
10
-
11
39
Rating
Plugs
Universal
Test
Set
(
TS
-
31
)
12
39
12
39
Auxiliary
Power
Module
Display
Module
13
39
14
39
Neutral
Transformers
15
Instantaneous
Fault
Protection
16
UL
Listings
and
File
Numbers
40
Ground
Fault
Protection
17
1
Courtesy of NationalSwitchgear.com

information
and
Instructions
Electronic
Trip
Unit
For
Siemens
Type
SB
Systems
'
Breaker
Additional
optional
features
include
:
Display
Module
for
local
current
monitoring
(
field
addable
)
Zone
Selective
Interlocking
Communications
for
remote
monitoring
Electronic
Trip
Unit
The
Electronic
Trip
Unit
is
a
microprocessor
controlled
multi
-
function
overcurrent
protective
device
for
application
with
Siemens
state
-
of
-
the
-
art
family
of
Type
SB
Systems
Breakers
.
The
adjustment
flexibility
provided
by
the
Elec
-
tronic
Trip
Unit
allows
the
user
to
easily
accommodate
load
changes
and
other
protective
requirements
while
still
assuring
optimum
coordination
.
In
addition
to
the
adjust
-
ment
protection
functions
,
the
trip
unit
is
designed
to
use
field
interchangeable
rating
plugs
.
These
rating
plugs
allow
the
ampere
rating
of
the
circuit
breaker
to
be
chang
-
ed
to
meet
specific
applications
.
For
ease
of
installation
and
interchangeability
in
the
field
,
the
trip
unit
has
been
designed
as
a
plug
-
in
unit
to
mount
directly
into
a
Type
SB
Breaker
frame
.
Current
sensors
within
the
Type
SB
Breaker
provide
signal
currents
and
operating
power
for
the
trip
unit
.
Therefore
,
when
the
circuit
breaker
is
closed
,
the
trip
unit
requires
no
external
connections
or
control
power
to
perform
its
protection
functions
.
Continuous
SIEM
£
WS
Rating
Plug
Rating
Plug
W
~
2
DD
0
A
o
SYSTEM
CHECK
14
Long
Time
Delay
2
.
S
-
/
=
^
'
21
^
30
25
Short
Time
5
Pickup
xi
,
8
7
^
Fixed
.
2
.
3
.
15
Short
Oe
7
aey
^
.
15
tr
„
,
Curve
Adjustments
Overcurrent
Protection
Configurations
Trip
units
are
available
in
six
basic
overcurrent
protection
configurations
to
meet
specific
protection
requirements
.
All
trip
units
have
Adjustable
Continuous
Current
and
Long
Time
Delay
.
Optional
protection
configurations
are
:
Protection
Configuration
Long
Time
/
Short
Time
Long
Time
/
Instantaneous
Long
Time
/
Short
Time
/
Instantaneous
Long
Time
/
Short
Time
/
Ground
Fault
Long
Time
/
Instantaneous
/
Ground
Fault
(
LIG
)
Long
Time
/
Short
Time
/
Instantaneous
/
Ground
Fault
As
standard
features
,
the
trip
unit
has
two
built
-
in
-
test
functions
and
a
fault
identification
function
.
System
Check
is
a
built
-
in
-
test
function
that
continuously
checks
the
status
of
the
microprocessor
and
protective
algorithms
.
A
green
LED
on
the
front
panel
blinks
approximately
every
3
seconds
when
the
microprocessor
is
properly
cycling
through
its
protection
routines
.
Integral
Test
is
a
built
-
in
-
test
that
allows
the
user
to
exercise
the
trip
unit
electronics
,
breaKer
-
magnetic
latch
,
and
breaker
mecha
-
nism
if
desired
.
LED
indicators
display
the
testing
status
.
Trip
Status
is
a
fault
identification
function
that
stores
information
when
a
current
fault
causes
the
trip
unit
to
trip
the
circuit
breaker
.
By
pressing
the
Query
button
the
user
can
display
the
cause
of
the
breaker
trip
by
illumi
-
nating
one
of
four
LED
'
s
:
OL
(
overload
)
,
ST
(
short
time
)
,
SC
(
short
circuit
)
,
or
GF
(
ground
fault
)
.
.
07
.
3
2
Ft
Instantaneous
Pickup
i
7
*
lr
Identifier
(
LS
)
23
24
b
Ground
Fault
26
Pickup
lg
=
%
ln
(
LI
)
FRAME
RATING
in
=
2000
A
(
LSI
)
(
LSG
)
Ground
Fault
Delay
Secs
@
.
5
ln
(
LSIG
)
o
Trip
O
O
O
O
Status
O
.
L
S
.
T
.
S
.
C
.
G
.
F
.
Query
—
Fault
Indicators
|
Q
Pass
Q
Testing
A
PM
TEST
Built
-
in
Test
Functions
Trip
Phase
G
.
F
o
»
oo
TS
31
Meter
Display
Module
Maximum
Demand
Present
Demand
_
Plug
-
in
Display
Module
100
nriri
Hi
u
i
90
80
Load
Monitor
-
J
Alarm
Set
Points
%
Continuous
Amps
Amps
Electronic
'
"
‘
rip
Unit
Adjustment
Panel
(
4
CC
0
A
illustrated
)
%
2
Courtesy of NationalSwitchgear.com

Information
and
Instructions
General
Information
,
Frame
Sizes
and
Frame
Ampere
Ratings
Frame
Sizes
/
Ratings
Combinations
RMS
Current
Sensing
The
Siemens
microprocessor
controlled
Electronic
Trip
Unit
executes
the
overcurrent
fault
protection
functions
of
the
Type
SB
Systems
Circuit
Breakers
.
The
adjustment
flexibility
provided
by
the
Electronic
Trip
Unit
allows
the
user
to
easily
accommodate
load
changes
and
other
protection
requirements
while
still
assuring
optimum
coordination
.
A
standard
feature
of
the
Electronic
Trip
Unit
is
RMS
current
sensing
.
As
opposed
to
peak
-
current
sensing
,
RMS
sens
-
ing
measures
the
true
heating
potential
of
the
current
waveform
.
This
allows
for
more
accurate
overcurrent
pro
-
tection
and
eliminates
nuisance
tripping
due
to
harmonic
distortion
of
the
current
waveform
.
Breaker
Frame
Ampere
Ratings
(
ln
)
Breaker
Frame
Size
800
A
400
A
800
A
2000
A
1200
A
1600
A
2000
A
4000
A
2500
A
3200
A
4000
A
Rating
Plugs
Field
interchangeable
rating
plugs
are
used
to
set
the
effective
ampere
rating
of
the
circuit
breaker
.
Available
rating
plugs
,
as
a
function
of
the
frame
ampere
ratings
,
are
given
in
the
following
table
.
Note
that
the
maximum
rating
plug
value
for
a
particular
Electronic
Trip
Unit
is
equal
to
the
frame
rating
;
the
minimum
is
equal
to
50
%
of
the
ln
.
A
rejection
scheme
is
built
into
the
rating
plugs
and
trip
units
to
prevent
the
insertion
of
a
rating
plug
into
a
trip
unit
for
which
it
is
not
intended
.
Siemens
Type
SB
Systems
Breaker
Three
physical
Type
SB
frame
sizes
are
presently
avail
-
able
.
These
are
the
800
A
,
2000
A
,
and
4000
A
.
The
interrupt
-
ing
ratings
of
these
frames
are
given
in
the
following
table
.
UL
Symmetrical
RMS
Amperes
Interrupting
Rating
(
A
.
I
.
R
.
)
Frame
Size
UL
Listed
Symmetrical
Amperes
800
A
4000
A
2000
A
Available
Rating
Plugs
Alternate
A
.
I
.
R
.
Rating
,
kA
@
240
V
ac
@
480
V
ac
@
600
V
ac
65
NA
85
65
65
NA
Rating
Plug
Values
(
Amperes
)
(
lr
)
Frame
Ampere
Rating
(
ln
)
42
50
NA
200
.
225
.
250
.
300
,
350
,
400
400
.
450
.
500
.
600
,
700
,
800
600
,
700
.
800
.
1000
,
1200
800
,
1000
,
1200
,
1600
400
A
800
A
1200
A
1600
A
Standard
A
.
I
.
R
.
Rating
,
kA
@
240
V
ac
@
480
V
ac
@
600
V
ac
150
100
100
100
100
100
50
65
85
1000
,
1200
.
1600
.
2000
1600
,
2000
.
2500
1600
,
2000
,
2500
,
3000
,
3200
2000
,
2500
,
3000
.
3200
,
4000
2000
A
2500
A
3200
A
4000
A
High
A
.
I
.
R
.
Rating
,
kA
@
240
V
ac
@
480
V
ac
@
600
V
ac
200
200 200
150 150
150
100 100
100
See
pages
38
and
39
for
a
complete
listing
of
trip
unit
and
rating
plug
catalog
numbers
.
Within
each
frame
size
is
a
series
of
available
frame
ampere
ratings
(
ln
)
.
The
frame
ampere
rating
is
determined
by
the
current
transformers
within
the
frame
.
Properly
rated
Electronic
Trip
Units
are
available
for
all
Type
SB
systems
breakers
.
The
trip
units
are
fully
field
installable
by
autho
-
rized
personnel
.
A
special
rejection
scheme
is
built
into
the
frames
and
trip
units
to
prevent
the
installation
of
a
trip
unit
into
a
frame
for
which
it
is
not
intended
.
This
rejection
scheme
is
illustrated
on
page
7
.
The
combinations
of
frame
sizes
and
frame
ampere
ratings
are
illustrated
in
the
follow
-
ing
table
.
3
Courtesy of NationalSwitchgear.com

Principles
of
Operation
The
microprocessor
reads
the
temporarily
stored
digital
voltages
and
compares
their
values
with
the
set
of
perma
-
nently
stored
values
that
correspond
to
the
user
-
selected
adjustment
settings
.
When
an
overcurrent
condition
is
detected
,
the
microprocessor
’
s
software
begins
to
process
the
appropriate
protection
function
.
During
the
processing
of
the
protection
function
,
the
microprocessor
continues
to
monitor
the
incoming
current
level
data
.
If
the
overcurrent
condition
continues
until
the
processing
is
completed
and
the
appropriate
delay
time
has
elapsed
,
a
tripping
com
-
mand
is
issued
by
the
microprocessor
.
The
tripping
command
from
the
microprocessor
causes
a
signal
to
be
sent
from
the
Electronic
Trip
Unit
to
the
low
energy
high
speed
magnetic
latch
in
the
circuit
breaker
.
The
signal
in
the
trip
unit
counteracts
the
permanent
magnet
in
the
latch
,
allowing
the
latch
to
trip
the
breaker
.
Principles
of
Operation
The
Electronic
Trip
Unit
uses
a
microprocessor
to
execute
the
numerous
numeric
and
logic
functions
programmed
in
the
unit
.
The
adjustments
on
the
trip
unit
face
allow
the
user
to
select
what
numerical
values
are
to
be
used
by
the
microprocessor
in
performing
its
protection
function
.
(
The
numerical
values
are
stored
in
the
processor
’
s
permanent
memory
.
)
Current
data
is
derived
from
current
sensors
mounted
in
the
Siemens
Type
SB
Breaker
.
These
sensors
are
current
transformers
.
As
passive
devices
,
they
provide
high
reli
-
ability
with
minimum
signal
error
while
providing
power
for
the
trip
unit
.
The
current
signals
from
the
transformers
are
converted
to
digital
voltages
in
the
trip
unit
.
These
digital
voltages
are
stored
in
temporary
memory
.
The
digital
signals
are
used
by
the
microprocessor
in
detecting
and
processing
overcurrent
conditions
.
ACT
SENSE
DECIDE
Continuous
imlv
10
»
95
Long
Time
osay
s
«
«
2.5
'
Si
—
r
Shan
Tim
*
Pickup
’
n
.
:
i
.
5
'
stwrt
-
3
2
n
I
iraununcous
Pickup
7
fs
'
ll
*
*
*
Jr
”
pitku
Current
Level
Signals
Trip
Command
30
n
mw
ft
\
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rr
*
r
o
»
io
5
Ucncr
Display
Module
1
»
1
»
Knwmum
p
*
mand
Prsnnt
Durand
j
W
-
tO
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nnn
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7
llnwuj
>
Amp
*
,
Electronic
Trip
Unit
Current
Transformers
Magnetic
Latch
The
Electronic
Trip
Unit
monitors
the
current
levels
at
an
equivalent
sam
-
pling
rate
of
353
samples
per
cycle
per
phase
.
It
then
decides
when
the
circuit
breaker
should
be
tripped
due
to
an
overcurrent
condition
.
Currenttransformers
sense
the
levels
of
the
phase
currents
and
provides
data
and
power
to
the
Electronic
Trip
Unit
.
The
magnetic
latch
causes
the
circuit
breaker
to
trip
when
it
receives
atrip
command
from
the
Electronic
Trip
Unit
.
4
Courtesy of NationalSwitchgear.com

"
0
=
3
o
~
o
0
0
o
O
”
0
0
0
O
=
3
C
Z
3
O
o
=
5
0
D
0
CQ
0
3
oi
Courtesy of NationalSwitchgear.com

Installation
Instructions
installing
the
Electronic
Trip
Unit
into
the
Circuit
Breaker
Steps
1
through
9
.
A
DANGER
h
Hazardous
Voltage
.
Will
cause
severe
injury
or
death
.
Turn
power
off
and
lock
out
supply
-
ing
device
before
installing
.
Spring
Charged
Contacts
Closed
«
iffigP
'
it
Contacts
Open
Spring
Discharged
If
trip
unit
is
not
already
installed
the
breaker
cannot
be
in
a
closed
position
.
CAUTION
:
To
prevent
possible
personal
injury
or
damage
the
SB
Breaker
should
be
in
the
“
Discharged
”
mode
prior
to
installing
a
trip
unit
1
.
)
Remove
the
8
screws
from
breaker
front
cover
.
To
install
the
trip
unit
,
the
front
cover
of
the
circuit
breaker
must
first
be
removed
.
This
is
done
oy
removing
the
eight
(
8
)
Phillips
head
screws
that
hold
the
front
cover
in
place
.
Installation
of
Electronic
Trip
Unit
Siemens
Type
SB
Breaker
has
a
built
-
in
interlock
device
that
prevents
the
circuit
breaker
from
being
closed
when
there
is
not
an
installed
trip
unit
.
This
same
interlock
device
will
trip
the
circuit
breaker
when
the
trip
unit
is
removed
.
2
.
)
Lift
off
front
cover
.
6
Courtesy of NationalSwitchgear.com

Installation
Instructions
5
.
)
Check
alignment
of
pins
and
holes
.
Siemens
Type
SB
Breaker
for
which
it
is
not
intended
.
This
scheme
consists
of
two
pins
on
the
support
plate
on
which
the
trip
unit
will
set
into
two
matching
holes
in
the
bottom
of
the
trip
unit
.
If
the
holes
in
the
bottom
of
the
trip
unit
cannot
be
aligned
with
the
pins
,
the
trip
unit
cannot
be
installed
in
the
Siemens
Type
SB
Breaker
.
If
there
is
any
doubt
about
a
trip
unit
being
the
proper
unit
for
a
Siemens
Type
SB
Breaker
,
hold
the
trip
unit
upside
down
and
check
the
alignment
of
the
pins
and
holes
.
3
.
)
Set
Ground
Fault
Protection
Switch
.
On
trip
units
with
ground
fault
protection
,
the
ground
fault
selection
switch
on
the
side
of
the
trip
unit
must
be
set
to
the
appropriate
sensing
scheme
-
Residual
or
Source
Ground
/
ZeroSequence
-
priorto
installing
the
trip
unit
.
These
ground
fault
sensing
schemes
are
discussed
on
page
18
.
WARNING
:
Do
not
attempt
to
modify
rejection
features
.
*
SIEMENS
<
Type
SB
Tnp
Ur
*
caf
He
sizr
.
rc
5
EKSL
r
rv
s
*
sa
*
.
-
®
5
&
*
CJC
*
*
Jl
*
L
«
C
r
'
*
*
*
»
4
»
Hi
7
*
-
2
4
.
)
Check
label
on
side
of
Trip
Unit
.
Before
attempting
to
install
the
trip
unit
,
check
the
label
on
the
side
of
the
unit
to
make
sure
that
it
is
the
proper
unit
for
the
Siemens
Type
SB
Breaker
.
A
ouilt
-
in
rejection
scheme
will
prevent
the
installation
of
a
trip
unit
into
a
6
.
)
Mate
pin
connectors
.
Mate
the
connector
half
on
the
back
of
the
trip
unit
with
its
corresponding
connector
half
in
the
circuit
breaker
.
7
Courtesy of NationalSwitchgear.com

Installation
Instructions
8
.
)
Secure
trip
unit
.
Secure
the
trip
unit
in
place
with
the
retaining
screw
located
at
the
top
of
the
unit
.
7
.
)
Lower
trip
unit
onto
support
plate
.
After
the
connector
has
been
mated
,
lower
(
push
)
the
trip
unit
onto
the
support
plate
.
The
pins
on
the
support
plate
will
fit
into
the
holes
in
the
bottom
of
the
trip
unit
.
9
.
)
Replace
the
front
cover
.
Replace
the
front
cover
.
Then
,
replace
the
eight
(
8
)
front
cover
screws
.
If
trip
unit
top
is
not
secured
properly
,
the
interlock
will
prohibit
closing
of
the
breaker
.
NOTE
:
Before
energizing
breaker
be
sure
to
install
a
proper
rating
plug
.
See
pages
10
and
11
.
8
Courtesy of NationalSwitchgear.com

Removal
Instructions
A
DANGER
h
Hazardous
Voltage
.
Will
cause
severe
injury
or
death
.
Turn
power
off
and
lock
out
supply
-
ing
device
before
installing
.
CAUTION
:
To
prevent
possible
personal
injury
or
breaker
damage
,
the
trip
unit
must
not
be
removed
when
the
circuit
breaker
is
“
Closed
”
or
“
Charged
”
.
Make
certain
the
circuit
breaker
is
“
Open
”
and
“
Dis
-
charged
”
as
illustrated
above
.
NOTE
:
When
practical
,
the
Electronic
Trip
Unit
should
be
removed
from
the
circuit
breaker
for
rating
plug
removal
or
insertion
.
Removing
Electronic
Trip
Unit
from
Circuit
Breaker
Steps
1
through
3
.
Before
starting
to
remove
the
trip
unit
,
setthe
circuit
breaker
to
the
“
Open
”
and
“
Discharged
”
positions
.
If
the
circuit
breaker
is
in
the
“
Closed
"
position
,
the
breaker
will
trip
when
the
trip
unit
is
removed
.
2
.
)
Remove
the
trip
unit
retaining
screw
.
Remove
the
front
cover
of
the
breaker
and
trip
unit
retaining
screw
.
Lift
the
trip
unit
from
the
support
plate
and
unmate
the
connector
.
Note
that
the
trip
unit
must
be
lifted
from
the
support
plate
high
enough
for
the
pins
on
the
support
plate
to
clear
the
holes
in
the
bottom
of
the
trip
unit
;
otherwise
,
the
connector
cannot
be
unmated
.
Remove
the
trip
unit
.
3
.
)
Remove
the
trip
unit
.
1
.
)
Remove
the
8
screws
from
breaker
front
cover
.
Lift
off
front
cover
.
9
Courtesy of NationalSwitchgear.com

Operations
-
Rating
Plug
Installation
:
Insertion
and
Removal
CAUTION
:
Do
not
attempt
to
force
improper
rating
plug
into
trip
unit
.
A
DANGER
h
Hazardous
Voltage
.
Will
cause
severe
injury
or
death
.
Turn
power
off
and
lock
out
supply
-
ing
device
before
installing
.
1
.
)
Check
label
on
Rating
Plug
.
Before
attempting
to
insert
the
rating
plug
,
check
the
label
on
the
rating
plug
to
verify
that
it
is
a
proper
plug
for
the
trip
unit
.
If
it
is
not
a
proper
plug
,
the
pins
on
the
plug
will
not
mate
with
the
connector
in
the
trip
unit
.
CAUTION
:
To
prevent
inadvertent
service
interrup
-
tion
,
the
rating
plug
must
not
be
removed
when
the
circuit
breaker
is
“
Closed
”
.
Make
certain
the
circuit
breaker
is
“
Open
”
as
illustrated
above
.
Inserting
and
Removing
Rating
Plug
from
Trip
Unit
Steps
1
through
7
.
Prior
to
inserting
or
removing
a
rating
plug
,
check
to
see
that
the
circuit
breaker
is
in
the
“
Open
"
position
.
The
circuit
breaker
should
always
be
in
the
“
Open
”
position
when
a
rating
plug
is
not
in
the
trip
unit
.
The
trip
unitwill
default
to
the
lowest
possible
settings
if
a
rating
piug
is
not
installed
.
To
prevent
the
insertion
of
a
rating
plug
into
a
trip
unit
for
which
it
is
not
intended
,
the
rating
plug
connector
in
the
trip
unit
has
been
keyed
to
reject
improper
plugs
.
2
.
)
Remove
the
two
(
2
)
plexiglass
shield
retaining
screws
.
Inserting
and
removing
the
rating
plug
requires
the
re
-
moval
of
the
clear
plexiglass
shield
.
To
remove
the
shield
,
unscrew
the
two
screws
that
hold
it
in
place
,
gently
pry
one
end
of
the
cover
loose
with
a
small
screwdriver
,
and
lift
.
0
3
.
)
Remove
plexiglass
shield
.
10
Courtesy of NationalSwitchgear.com

Operations
-
Rating
Plug
Installation
:
Insertion
and Removal
*
#
I
I
T
,
#
I
*
\
I
6
.
)
Replace
the
two
(
2
)
plexiglass
shield
retaining
screws
.
4
.
)
Press
the
plug
into
place
(
or remove
)
.
To
insert
a
rating plug
in
the
trip
unit
,
align
the
plug
with
the
plug
receptacle
and
press
the
plug
into
place
.
The
clips
on
the
rating
plug
and the
compression
fitting
of
the
plug
hold
the
plug
in
place
,
eliminating
the
need
for
screws
or
latches
.
The
plug
will
“
snap
”
into
place
without excessive
force
.
Do
not
force
the
rating plug
into
place
.
To
remove
a
rating plug
,
squeeze
the
clips
and
pull
the
plug
from
the
plug
receptacle
.
Since
the
plug
is held
in
place
by
compression
,
some
force
will
be
required
to
remove
the
plug
.
Do
not
close
the
circuit breaker
with
the
rating
plug
removed
from
the
trip
unit
.
,
r
*
P
(
*
n
«
7
.
)
Seal
the
cover
.
After
the
cover
has
been
replaced
a
wire
lock
may
be
inserted
through
holes
in
the
screws
and sealed
with
a
lead
seal
.
This
will
help
prevent
tampering
by
unauthorized
personnel
.
Slide
the
protective
shield
into
the
top
lip
of
the
trip
unit
,
bow
slightly
in
middle
,
and
press
down
with
thumb
on
bottom
to
snap
shield into
place
.
11
Courtesy of NationalSwitchgear.com

Operations
-
Functions
and
Adjustments
A
DANGER
Hazardous
Voltage
.
Will
cause
severe
injury
or
death
.
Turn
power
off
and
lock
out
supply
-
ing
device
before
installing
.
Removing
and
Replacing
the
Plexiglass
Cover
To
remove
the
plexiglass
cover
unscrew
the
two
screws
that
hold
it
in
place
,
and
gently
pry
one
end
of
the
cover
loose
with
a
small
screwdriver
.
After
the
rating
plug
has
been
installed
and
any
necessary
adjustments
have
been
made
,
the
cover
must
be
replaced
to
prevent
unauthorized
adjustments
(
see
pages
10
and
11
,
steps
2
,
3
,
5
,
6
,
and
7
)
.
Electronic
Trip
Unit
Functions
Displayed
and
accessible
on
the
front
panel
of
the
trip
unit
are
the
adjustments
,
switches
,
and
indicators
that
are
available
to
the
user
for
local
control
,
test
,
and
monitoring
.
These
include
:
•
System
Check
Indicator
•
Fault
Protection
Adjustments
•
Trip
Query
Switch
and
Indicators
•
Integral
Test
Switches
and
Indicators
•
Current
Demand
Indicators
(
Optional
Display
Module
)
.
Also
accessible
on
the
front
panel
is
a
receptacle
for
an
external
test
set
and
power
supply
.
The
trip
unit
has
factory
-
installed
capability
for
zone
selective
interlocking
and
communications
for
remote
monitoring
.
These
functions
are
accessible
via
the
TS
-
31
Test
Port
.
Setting
the
Fault
Protection
Adjustments
The
Electronic
Trip
Unit
executes
its
overcurrent
protection
functions
based
on
the
rating
plug
value
and
the
setting
of
the
current
adjustments
.
Therefore
,
care
should
be
taken
by
the
user
to
make
proper
selections
and
settings
.
To
avoid
potential
nuisance
tripping
,
while
changing
set
-
tings
,
Siemens
recommends
that
all
adjustments
be
made
with
the
Siemens
Type
SB
Breaker
in
the
"
Open
"
position
.
To
set
an
adjustment
,
place
a
slotted
screw
driver
onto
the
point
-
to
-
point
adjustment
switch
and
rotate
the
switch
to
the
desired
setting
.
The
following
figures
and
text
illustrate
and
describe
the
fault
protection
adjustments
.
All
pick
-
up
adjustments
,
except
ground
fault
,
are
multiples
of
the
rating
plug
value
,
lr
.
Ground
fault
pick
-
up
is
a
multiple
of
the
frame
ampere
rating
,
ln
.
All
pick
-
up
settings
are
RMS
amperes
or
values
.
2000
A
Electronic
Trip
Unit
Adjustment
Panel
shown
with
plexi
-
glass
cover
removed
and
access
adjustment
switches
shown
.
#
12
Courtesy of NationalSwitchgear.com

Operations
-
Fault Protection
Adjustments
Trip
Unit
Current
Shaping
Adjustments
(
This
curve
is
for
illustration
purposes
only
)
Amperes
in
Multiples
of
Rating
Plug
Value
.
1
1
10000
(
1
)
Continuous
Ampere
Setting
Region
The
allowable continuous
operating
amperes
is
set to
a
percent
of
the
rating
plug
value
.
Note
that
the
maximum
continuous
ampere
is
set
by
the
rating
plug
value
,
lr
.
(
2
)
Long
Time
Delay Region
The
long
time
delay
is
set to
an
inverse
l
2
t
ramp
function
delay
calibrated
,
at
6
times
the
rating plug
value
,
lr
.
(
3
)
Short
Time
Pickup
Region
The short
time
pickup
is
set
to
a
multiple
of
the
rating
plug
value
,
lr
.
(
4
)
Short
Time
Delay
Region
The short
time
delay
is
set to
either
a
fixed
delay
(
illustrated
)
or an
inverse
l
2
t
ramp
function
delay
calibrated
at
8
times
the
rating plug
value
,
lr
.
(
5
)
Instantaneous
Pickup
Region
The instantaneous
pickup
is
set to
a
multiple
of
the
rating
plug
value
,
lr
.
(
6
)
Ground
Fault
Pickup
Region
The
ground
fault
pickup
is
set
to
a
percent
of
the
frame
ampere
rating
,
ln
.
(
7
)
Ground
Fault
Delay
Region
The
ground
fault
delay
is
set to
either
a
fixed
delay
(
illustrated
)
or an
inverse
l
2
t
ramp
function
delay
calibrated
at
one
half of
the
frame
ampere
rating
,
ln
.
1000
100
K
ig
=
%
in
100
1000
10
(
6
)
H
3
1
CD
3
(
/
)
CO
o
o
13
(
7
)
o
.
co
K
.
1
O
<
o
CD
.
01
1000
100
13
Courtesy of NationalSwitchgear.com

Operations
-
Long
Time
Fault Protection
Adjustable
Continuous
Amps
and
Adjustable
Long
Time
Delay
Adjustable
Long
Time
Delay
The
Long
Time
Pickup
is
nominally
set at
115
percent
of
the
continuous
amps
setting
.
The
Long
Time
Delay
adjust
-
ment
is used
to set
the
tripping delay
of
the
Type
SB
based
on
the
magnitude
of
the
overcurrent
condition
.
On
Siemens
Type
SB
trip
units
,
the
long
time
delay
,
which
is
an
inverse
l
2
t
ramp
function
,
may
be
set to
a
calibrated value
of
2.5
,
4
,
5.5
,
8
,
10
,
14
,
17
,
21
,
25
,
or
30
seconds
at
a
current
equal
to
6
times
I
SIEMENS
Continuous
Rating Plug
ir
=
2000
A
o
SYSTEM
CHECK
f
14
Long
Time
"
17
Delay
Secs
@
6
x
lr
Adjustable
Continuous
Amps
The
Continuous
ampere
adjustment
sets
the
current
levei
at
which the
breaKer
will
continuously
operate
without initiat
-
ing
a
tripping
sequence
.
On
Siemens
Type
SB
Trip
Units
,
the
continuous
operating
current
may
be
set to
50
,
60
,
65
,
70
,
75
,
80
,
85
,
90
,
95
,
and
100
%
of
the
rating plug
value
lr
.
xlr
10
100
1
.
1
10000
'
Contauoug
Owaasrsg
Ojriort
'
000
100
o
c
o
o
0
)
GO
<
1
>
P
10
Long
Time
Delay
1
i
.
1
%
lf
70
75
65 80
Available
Switch
Settings
(
All
Frame
Sizes
)
>
/
(
for
Adjustable
Continuous
Amps
A
-
60
50
'
100 95
Continuous
Operating
Current
14
Courtesy of NationalSwitchgear.com

Operations
-
Short
Time
Fault
Protection
Adjustable
Short
Time
Pickup
and
Adjustable
Short
Time
Delay
Adjustable
Short
Time
Delay
The
Short
Time
Delay
adjustment
is
used
to
set
the
time
interval
the
breaker
will
wait
before
responding
to
the
current
value
selected
on
the
Short
Time
Pickup
adjust
-
ment
.
There
are
two
modes
of
operation
of
this
adjustment
on
all
Type
SB
Trip
Units
;
one
is
a
fixed
delay
,
the
other
is
an
inverse
l
2
t
ramp
delay
.
The
l
2
t
Delay
has
the
character
-
istic
of
being
inversely
proportional
to
the
square
of
the
magnitude
of
the
overcurrent
condition
.
This
means
that
higher
overcurrent
conditions
have
shorter
delays
and
conversely
lower
overcurrent
conditions
have
longer
de
-
lays
.
This
characteristic
allows
for
better
coordination
with
downstream
circuit
breakers
and
fuses
.
In
the
fixed
delay
mode
,
the
Short
Time
Delay
may
be
set
to
.
07
,
.
1
,
.
15
,
.
2
,
or
.
3
seconds
.
In
the
inverse
l
2
t
ramp
Short
Time
Delay
mode
,
the
delay
may
be
set
to
a
calibrated
value
of
.
07
,
.
1
,
.
15
,
.
2
,
or
.
3
seconds
at
a
current
equal
to
8
times
lr
.
3
3.5
2.5
,
4
Short
Time
"
5
Pickup
H
(
V
Xlr
6
1.5
8
7
'
"
Fixed
.
2
.
3
.
15
,
.
07
Short
Say
fTx
.
,
•
3
.
2
pt
.
07
Adjustable
Short
Time
Pickup
The
Short
Time
Pickup
adjustment
is
used
to
set
the
level
of
high
current
the
breaker
will
carry
for
a
short
period
of
time
without
tripping
.
This
adjustment
,
together
with
the
Short
Time
Delay
,
allows
downstream
breakers
time
to
clear
short
circuit
faults
without
tripping
the
upstream
breakers
.
On
trip
units
for
the
800
A
and
2000
A
Type
SB
frame
sizes
,
the
Short
Time
Pickup
may
be
set
to
1.5
,
2
,
2.5
,
3
,
4
,
5
,
6
,
7
,
8
,
or
9
timeslr
.
Ontripunitsforthe
4000
ATypeSBframesize
,
the
short
time
pickup
may
be
set
to
1.5
,
2
,
2.5
,
3
,
3.5
,
4
,
5
,
6
,
7
,
or
8
times
lr
.
xlr
100
10
1
1
looro
Continuous
Operating
Current
I
Short
Time
Fixed
Delay
1000
.
-
—
Long
Time
Delay
1
A
Fixed
2
V
,
\
\
\
100
N
5
li
.
1
s
•
c
c
o
s
I
i
V
co
10
Available
Switch
Settings
(
All
Frame
Sizes
)
Short
nme
Pickup
o
E
\
xlr
10
V
100
11
1
10000
Continuous
Operating
Current
v
Si
.
1
\
1000
l
!
s
Long
Time
Delay
!
Short
Time
Fixed
Delay
N
\
.
01
100
xlr
10
1
10
C
.
1
v
>
1
C
0
C
0
•
O
c
Continuous
Operating
Current
o
S
'
15
:
O
0
)
10
CO
\
<
\
<
n
Short
Time
Pickup
A
Short
Time
j
\
'
Pickup
1000
£
Long
Time
Delay
Short
Time
l
2
t
Delay
V
1
100
CO
V
>
v
>
\
\
K
\
h
$
5
*
«
.
1
£
cq
10
Nk
N
’
u
&
E
Available
Switch
Settings
(
All
Frame
Sizes
)
i
F
1
2
3
-
5
Short
Time
Ft
Delay
.
Short
4
Time
Pickup
2.5
.
M
(
V
\
.
1
Available
Switch
Settings
for
Short
Time
Pickup
6
1.5
8
80
CA
and
2000
A
Frame
Sizes
4000
A
Frame
Size
01
Short
Time
Delay
Short
Time
Pickup
15
Courtesy of NationalSwitchgear.com

Operations
-
Instantaneous
Fault
Protection
Adjustable
Instantaneous
Pickup
Instantaneous
Override
On
all
trip
units
,
an
instantaneous
override
function
has
been
provided
.
It
is
set
nominally
at
the
short
time
rating
of
the
respective
breaker
frame
size
.
This
allows
the
breaker
to
ride
through
high
faults
up
to
its
short
time
capability
;
however
,
it
is
self
-
protecting
above
these
values
.
Instantaneous
Pickup
Short
Time
kA
Rating
(
.
500
seconds
max
.
)
Breaker
Frame
Size
25
800
A
2000
A
4000
A
35
Adjustable
Instantaneous
Pickup
The
Instantaneous
Pickup
adjustment
is
used
to
set
the
current
level
at
which
the
breaker
will
trip
without
an
intentional
time
delay
.
Non
-
delayed
tripping
,
as
a
result
of
a
severe
overcurrent
condition
,
minimizes
potential
dam
-
age
to
electrical
systems
and
equipment
.
On
trip
units
for
the
800
A
and
2000
A
Type
SB
frame
sizes
,
the
Instanta
-
neous
Pickup
adjustment
may
be
set
to
1.5
,
2
,
3
,
4
,
5
,
6
,
7
,
8
,
10
,
or
12
times
lr
.
On
trip
units
for
the
4000
A
frame
size
,
the
adjustment
may
be
set
to
1.5
,
2
,
3
,
4
,
5
,
6
,
7
,
8
,
9
,
or
10
times
lr
.
65
Discriminator
Circuit
(
Making
Current
Release
)
This
circuit
overrides
the
short
time
delay
function
should
the
breaker
attempt
to
close
into
a
faulted
system
,
tripping
the
breaker
instantaneously
.
The
discriminator
function
is
enabled
for
the
6
cycles
of
current
flow
,
after
which
normal
short
time
characteristics
operate
.
xlr
100
10
.
1
1
10000
Continuous
Operating
Current
&
V
xlr
10
s
1
100
.
1
10000
1000
—
Long
Time
Delay
1
|
wt
1000
100
A
\
co
\
c
o
s
o
\
\
100
10
o
\
CO
$
0
T
3
E
C
F
V
c
o
Short
Time
-
Pickup
CD
$
£
10
1
Instantaneous
Override
CD
E
F
-
1
.
1
Short
Time
Fixed
Delay
.
1
.
01
Instantaneous
Override
(
Illustrated
with
Short
Time
Fixed
Delay
)
.
01
Xlr
7
Available
Switch
Settings
for
Instantaneous
Pickup
7
80
CA
ard
2000
A
Frame
Sizes
4000
A
Frarre
Size
Instantaneous
Pickup
i
16
Courtesy of NationalSwitchgear.com

Operations
-
Ground
Fault Protection
Adjustable
Ground
Fault
Pickup
and
Adjustable
Ground
Fault
Delay
Ground
Fault
Sensing
Schemes
The
trip
unit
can
be
configured
to
accommodate the
following
ground
fault
sensing
schemes
.
•
3
-
Phase
,
3
-
Wire
Residual
•
3
-
Phase
,
4
-
Wire Residual
•
Source Ground
•
Zero
Sequence
All
that
is
required
by
the
user
to
configure
the
trip
unit
to
support
these
protection
schemes
is
to
set
the
ground
fault
selection switch
to
the
desired
configuration
.
The
selection
switch is
on
the
left
side
of
the
trip
unit
and
must
be
set
prior
to
the
trip
unit
being
installed
in
the
Type
SB
Breaker
,
see
Installation
Instructions
on
pages
6
through
8
.
23
24
22
.
25
Ground
Fault
~
26
Pickup
27
ig
=
%
in
4
FRAME
RATING
ln
=
2000
A
20
30
28
.
4
.
5
Fixed
.
3
.
1
Ground
^
IP
2
Delay
,
Secs
•
3
@
.
51
„
.
4
Ft
.
2
•
V
.
1
.
5
Adjustable
Ground
Fault
Pickup
The
Ground
Fault
Pickup
adjustment
is
used
to set
the
level
of
ground
current at
which
circuit
interruption
will
be
initi
-
ated
.
Together
with
the
Ground
Fault
Delay
,
this
adjustment
allows
selective
tripping
between
main and
feeder
or
other
downstream
breakers
.
The
available
ground
fault
pickup
settings
,
as
a
percent
of
the
Type
SB frame
ampere
rating
ln
are
given
in
the
table
below
.
In
compliance
with
the
National
Electric
Code
(
NEC
230
-
95
)
,
no
trip
point
setting
exceeds
1200
amperes
.
Ig
=
%
ln
1
10
100
1000
10
1
Ground
Fault
Fixed
Delay
Ground
Fault
Pickup
—
Fixed
.
4
.
5
1
.
2
-
XI
T
§
.
1
£
J
V
Available
Switch
Settings
(
All
Frame
Sizes
)
Adjustable
Ground
Fault
Delay
CO
I
<
D
E
Frame
Ampere
Rating
ln
F
Available
Setting
%
ln
1
400
A
800
A
20 25
30
40 50
60
70 80 90
20 25
30
40
50 60 70 80 90 100
100
Ground fault
Fixed
Delay
1200
A
1600
A
20 25
30
40 50 60
70 80 90 100
20
26
32
38
44
50 56 62 68
75
2000
A
2500
A
20
23
27
30 35
40
45
50
55
60
20
23
26
29
32
35 38
41
44
48
C
1
3200
A
4000
A
20
21
23
25
27
29
31 33 35 37
20
21 22
23
24
25
26
27
28
30
|
Q
=
%
'
n
Adjustable
Ground
Fault
Delay
The
Ground
Fault
Delay adjustment
is
used
to set
the time
interval
the
breaker
will
wait
before
responding
once
the
ground
fault
pickup
level has been
reached
.
There
are
two
modes
of
operation
of
this
adjustment
on
all Electronic
trip
units
;
one
is
a
fixed
delay
and
the
other is
an
inverse
l
2
t
ramp
delay
.
In
the
fixed
delay
mode
,
the
Ground
Fault
Delay
may
be
set to
.
1
,
.
2
,
.
3
,
.
4
,
or
.
5
seconds
.
In
the
inverse
Ft
ramp
delay
mode
,
the
delay
may
be
set
to
a
calibrated value
of
.
1
,
.
2
,
.
3
,
.
4
,
or
.
5
seconds
at
a
current
equal
to
0.5
times
the
frame
ampere
rating
ln
.
The
inverse
l
2
t
ramp
delay
reverts to
a
fixed
delay
of
the
same
value
when
the
ground
current
(
lg
)
exceeds
50
percent
of
the
frame
rating
(
ln
)
.
Ground
Fault
Memory
Circuit
All
Siemens
Type
SB
Trip
Units
with
ground
fault
protection
come
equipped
with
a
ground
fault
memory
circuit
.
This
circuit
effectively
integrates
ground
fault
currents
with
time
.
This
provides
an
added
protection
by preventing
the
ground
fault
delay
circuits
from
being
resetto
zero
when
the
ground
fault
currents
are
intermittent
and
erratic
.
The
time
constants
for
the
current
integration
are
preset
within
the
trip
unit
as
a
function
of
the
Ground
Fault
Delay
.
1
10
100
1
COO
10
Ground
Fault
Pickup
I
Ground
Fault
l
2
t
Delay
1
\
Secs
•
c
©
.
5
l
„
C
-
\
a
5
£
Available
Switch
Settings
(
Ail
Frarre
Sizes
)
Adjustable
Ground
Fault
Delay
1
i
L
Ground
Fault
I
2
!
Delay
01
Ground
Fault
Delay
17
Courtesy of NationalSwitchgear.com

Operations
-
Ground
Fault
Sensing
Schemes
ground
fault
occurs
,
the
fault
current returns
viaa
path
other
than
the neutral
.
Therefore
,
the
vector
sum
of
the
phase
currents
no
longer
equals
the
neutral
current
.
This
current
differential
is detected
by
the
trip
unit
and used
in
the
execution
of
the
ground
fault
protection
function
.
Source
Ground
.
In
this scheme
,
the
phase
currents
are
not
used
in
detecting
and
processing
ground
faults
.
The
trip
unit
executes
the
ground
fault
protection
function
based
on
data
from
a
ground
current
sensor
.
This
sensor
is located
on
the
neutral
connection
to
ground
at
the service
entrance
,
and is connected
to
the
neutral
transformer
input
terminals
on
the
trip
unit
.
Zero
Sequence
.
This
scheme
is
very
similar
to
the
Residual
Schemes
.
A
core
balance
type
current
sensor
encircles
all
phase
conductors
and
neutral
on a
4
-
wire
system
.
Under
normal
system
conditions
or a
phase
-
to
-
phase
fault
condi
-
tion
,
there is
no
output
from
the
sensor
to
the
trip
unit
because
the
vector
sum
of
the
currents
through
the
sensor
window is
zero
.
If
a
ground
fault
occurs
,
the
ground
current
is
not
seen
by
the
sensor
,
which
returns
to
the
source
by
a
path
other than
through
the
sensor
window
.
The
sensor
detects
this
current
unbalance and
provides
the data
required
by
the
trip
unit
to
execute
the
ground
fault
protec
-
tion
function
.
The
zero
sequence
sensor
is connected
to
the
neutral
transformer
input
on
the
trip
unit
.
Ground
Fault
Sensing
Scheme
The
following
are
brief
descriptions
of
the
ground
fault
sensing
schemes
as
they
relate
to
the
Siemens
Type
SB
Trip
Unit
.
Detailed
technical and
application
information
of
the
ground
fault
sensing
schemes is
contained
in
NEMA
Standard
No
.
PB
2.2
“
Application
Guide
for
Ground
Fault
Protective Devices
for
Equipment
”
.
For
information
on
Ground
Fault
Selection Slide Switch
,
refer
to
page
7
.
Residual
(
3
-
Phase
,
3
-
Wire
)
.
Under
normal
system
conditions
(
without
ground
fault
)
,
the
vector
sum
of
the
phase
currents
being
monitored
by
the
trip
unit
is
zero
.
This is
also
true
under the condition
of
an
overcurrent
phase
-
to
-
phase
fault
and
phase
-
unbalance
condition
.
When
a
phase
-
to
-
ground
fault
occurs
,
the
vector
sum
of
the
phase
currents
is
directly
proportional
to
the
magnitude
of
the
fault
.
The
trip
unit
’
s
microprocessor
uses
this
vector
sum
data
in
the
execution
of
the
ground
fault
protection
function
.
The
trip
unit
utilizes
the internal breaker
current
transformers
.
No
external
cur
-
rent
transformers
are
required
.
Residual
(
3
-
Phase
,
4
-
Wire
)
.
In
the
3
-
Phase
,
4
-
Wire Resi
-
dual
scheme
a
fourth
current
transformer
is connected
in
the
neutral
conductor
to
“
Sense
"
normal neutral
currents
.
Under
normal
system
conditions the
vector
sum
of
the
currents
in
all
phases
equals
the
neutral
current
.
This
is
also
true
under the
condition
of
an
overcurrent
phase
-
to
-
phase
fault
and
phase
-
unbalance condition
.
When
a
phase
-
to
-
Break
©
*
Mid
Current
Sensors
Power
Transformer
7
T
o
=
V
—
»
—
=
M
<
4
Circuit
Breaker
<
4
Source
Ground
Current
.
Neutral Bus
•
v
Ground
Bus
Alternate
Position
Of
Zero
Sequence
Sensor
Zero
Sequence
Sensor
’
r
Neutral Bus
Current Sensors
\
Mam
/
\
rT
>
Trip
Urn
:
Phase
&
Neutra
Connection
to
Load
II
Neutral
U
I
:
Source
I
Signal
Inputs
i
Trip
Load Load
Unit
Neutral
Disconnect
Lir
-
c
Residual
Sensing
.
Circuit
Breaker
Wiring
for Ground
Protection
(
3
-
Phase
,
4
-
Wire
System
Shown
)
.
Zero
Sequence
Ground
Fault Protection
.
18
Courtesy of NationalSwitchgear.com