Schweitzer Engineering Laboratories SEL-251C-1 User manual

SEL
-
251
C
-
1
PHASE
OVERCURRENT
RELAY
WITH
VOLTAGE
AND
DISTANCE
CONTROL
GROUND OVERCURRENT
RELAY
SELECTABLE
SETTING GROUPS
CIRCUIT
BREAKER
MONITOR
SELOGIC
®
CONTROL
EQUATIONS
INSTRUCTION
MANUAL
SCHWEITZER
ENGINEERING
LABORATORIES
,
INC
.
2350
NE
HOPKINS
COURT
PULLMAN
,
WA
USA
99163
-
5603
TEL
:
(
509
)
332
-
1890
FAX
:
(
509
)
332
-
7990
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The
software
(
firmware
)
,
schematic
drawings
,
relay
commands
,
and
relay
messages
are
copyright
protected
by
the
United
States
Copyright
Law
and
International
Treaty
provisions
.
All
rights
are
reserved
.
You
may
not
copy
,
alter
,
disassemble
,
or reverse
-
engineer
the
software
.
You
may
not
provide
the
software
to
any
third
party
.
All
brand
or
product
names
appearing
in
this
document
are
the trademark
or
registered
trademark
of
their
respective
holders
.
Schweitzer
Engineering
Laboratories
,
SELogic
,
Connectorized
,
Job Done
,
SEL
-
PROFILE
,
SEL
-
5030
ACSELERATOR
,
and
|
SEL
|
are
registered
trademarks
of
Schweitzer
Engineering
Laboratories
,
Inc
.
The
English
language
manual
is the
only
approved
SEL
manual
.
Copyright
©
SEL
1993
,
1994
,
1995
,
1996
,
1997
,
2000
,
2002
(
All
rights
reserved
)
Printed
in
USA
.
This
product
is
covered
by
U
.
S
.
Patent Numbers
:
5
,
041
,
737
;
5
,
477
,
408
;
5
,
479
,
315
;
and
5
,
602
,
707
.
This
product
is
covered
by
the standard
SEL
10
-
year
warranty
.
For
warranty
details
,
visit
www
.
selinc
.
com or
contact
your
customer
service
representative
.
PM
251
C
-
02
Courtesy of NationalSwitchgear.com

This device is
shipped
with
default
passwords
.
Default
passwords
should be
changed
to
private
passwords
at
installation
.
Failure
to
change
each
default
password
to
a
private password
may
allow
unauthorized
access
.
SEL
shall
not
be
responsible
for
any
damage resulting
from
unauthorized
access
.
Warning
Cet
equipement
est
expedie
avec
des
mots
de
passe
par
defaut
.
A
Installation
,
les
mots
de
passe par
defaut
devront
etre
changes
pour
des
mots
de
passe
confidentiels
.
Dans
le
cas
contraire
,
un acces non
-
autorise
a
I
'
equipement
pourrait
etre
possible
.
SEL
decline
toute
responsabilite
pour
tout
dommage
resultant de
cet
acces
non
-
autorise
.
ATTENTION
!
20001120
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MANUAL
CHANGE
INFORMATION
The
date
code
at
the
bottom
of
each
page
of
this
manual
reflects
the
creation
or
revision
date
.
Date
codes
are
changed
only
on
pages
that
have
been
revised
and
any
following
pages
affected
by
the
revisions
(
i
.
e
.
,
pagination
)
.
If
significant
revisions
are
made
to
a
section
,
the
date
code
on
all
pages
of
the
section
will
be
changed
to
reflect
the
revision
date
.
Each
time
revisions
are
made
,
both
the
main
table
of
contents
and
the
affected
individual
section
table
of
contents
are
regenerated
and
the
date
code
is
changed
to
reflect
the
revision
date
.
Changes
in
this
manual
to
date
are
summarized
below
(
most
recent
revisions
listed
at
top
)
.
Revision
•
::
.
.
:
*
Y
;
:
.
;
'
.
'
:
Summary
o
Date
,
..
The
Manual
Change
Information
section
has
been
created
to
begin
a
record
of
revisions
to
this
manual
.
All
changes
will
be
recorded
in
this
Summary
of
Revisions
table
.
This
revision
includes
the
following
changes
:
-
Replaced
Standard
Product
Warranty
page
with
warranty
statement
on
cover
page
.
Appendix
A
:
-
Updated
Firmware
Version
information
.
20020212
This
revision
includes
the
following
changes
:
-
Reissued
entire
manual
Section
2
:
-
Added
Frequency
and
Rotation
information
-
Incorporated
"
New
SEL
-
200
Series
Optical
Isolator
Logic
Input
Rating
"
addendum
.
Section
6
:
-
Incorporated
"
Jumper
Installation
Instructions
"
addendum
.
-
Incorporated
"
SEL
-
200
Series
(
Shallow
)
Relay
Hardware
"
addendum
.
-
Added
Figure
6.4
:
Panel
Cutout
Diagram
for
Panel
-
Mount
Relays
.
20000515
970421
This
revision
includes
the
following
changes
:
Appendix
A
:
-
Added
New
Firmware
Versions
Date
Code
20020212
Manual
Change
Information
SEL
-
251
C
-
1
Instruction
Manual
l
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SEL
-
251
C
-
1
INSTRUCTION
MANUAL
TABLE
OF
CONTENTS
INTRODUCTION
SECTION
1
SPECIFICATIONS
SECTION
2
SECTION
3
COMMUNICATIONS
EVENT
REPORTING
SECTION
4
SECTION
5
:
APPLICATIONS
SECTION
6
INSTALLATION
MAINTENANCE
AND
TESTING
SECTION
7
APPENDICES
SECTION
8
Appendix
A
:
Firmware
Versions
Appendix
B
:
Main
Board
Jumper
Connector
and
Socket
Locations
Appendix
C
:
Onebus
:
Program
to
Compute
Test
Set
Settings
for
Testing
Distance
Relays
Table
of
Contents
SEL
-
251
C
-
1
Instruction
Manual
Date
Code
20020212
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INTRODUCTION
TABLE
OF
CONTENTS
l
-
l
Getting
Started
..
.
Overview
General
Description
1
-
1
1
-
2
Table
of
Contents
SEL
-
251
C
-
1
Instruction
Manual
Date
Code
20000515
i
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SECTION
1
:
INTRODUCTION
GETTING
STARTED
If
you
are
not
familiar
with
this
relay
,
we
suggest
that
you
read
this
introduction
,
then
perform
the
Initial
Checkout
Procedure
in
Section
7
:
MAINTENANCE
AND
TESTING
.
OVERVIEW
The
SEL
-
251
C
-
1
Relay
is
designed
to
protect
distribution
buses
and
backup
distribution
feeders
for
all
fault
types
.
The
following
list
outlines
protective
features
,
performance
,
and
versatility
gained
when
applying
the
SEL
-
251
C
-
1
Relay
to
your
installations
.
Develop
traditional
and
advanced
schemes
using
flexible
SELOGIC
®
Control
Equations
Phase
overcurrent
elements
have
voltage
and
distance
control
for
load
security
Ground
/
Residual
overcurrent
elements
cover
ground
faults
Choose
fast
or
electromechanical
reset
characteristic
for
time
-
overcurrent
elements
Undervoltage
logic
detects
high
-
side
transformer
fuse
operations
Six
selectable
setting
groups
cover
all
bus
protection
contingencies
Circuit
breaker
monitor
sums
interrupted
current
in
each
pole
to
aid
maintenance
Selectively
backup
distribution
feeder
relays
Eleven
-
cycle
event
report
simplifies
fault
and
system
analysis
Comprehensive
voltage
,
current
,
power
,
unbalance
,
and
demand
metering
Connects
to
SEL
-
RD
Relay
Display
for
easy
information
access
The
SEL
-
251
C
-
1
Relay
improves
every
aspect
of
bus
protection
.
•
Security
:
Phase
distance
supervision
avoids
load
encroachment
•
Reliability
:
Field
-
proven
hardware
;
new
backup
concepts
•
Flexibility
:
SELOGIC
Control
Equations
handle
virtually
every
conceivable
scheme
•
Capability
:
Brings
transmission
relay
features
to
distribution
applications
•
Economy
:
Low
price
and
unique
features
make
the
relay
an
exceptional
value
Introduction
SEL
-
251
C
-
1
Instruction
Manual
Date
Code
20000515
1
-
1
Courtesy of NationalSwitchgear.com

GENERAL
DESCRIPTION
The
SEL
-
251
C
-
1
Relay
protects
and
monitors
distribution
busses
and
backs
up
distribution
feeder
relays
.
It
offers
important
new
and
unique
features
like
user
-
programmable
SELOGIC
Control
Equations
and
selectable
setting
groups
.
The
advanced
relay
design
enhances
security
,
reliability
,
sensitivity
,
and
operation
.
SELomr
Control
Equations
:
The
Next
Step
in
Programmable
Relay
Logic
In
1987
,
SEL
invented
Programmable
Mask
Logic
.
The
SEL
-
251
C
-
1
Relay
offers
SELOGIC
Control
Equations
,
the
next
step
in
user
-
programmability
.
SELOGIC
Control
Equations
include
ANDing
,
ORing
,
and
inverting
functions
,
timing
,
and
programmable
inputs
and
outputs
.
SELOGIC
Control
Equations
add
power
and
flexibility
while
simplifying
programming
.
Phase
.
Ground
,
and
Negative
-
Sequence
Overcurrent
Protection
Phase
overcurrent
elements
detect
phase
faults
.
On
heavily
-
loaded
feeders
,
phase
distance
or
undervoltage
torque
control
of
phase
overcurrent
elements
adds
security
.
Choose
between
three
-
phase
and
single
-
phase
-
pair
phase
distance
or
undervoltage
torque
control
.
Ground
/
Residual
overcurrent
elements
detect
ground
faults
,
and
external
inputs
can
torque
control
selected
overcurrent
elements
.
There
are
two
reset
characteristic
choices
for
the
time
-
overcurrent
elements
.
One
choice
resets
the
elements
if
current
drops
below
pickup
for
at
least
one
cycle
.
The
other
choice
emulates
electromechanical
induction
disc
elements
where
the
reset
time
depends
on
the
time
dial
setting
,
the
percentage
of
disc
travel
,
and
the
amount
of
current
between
zero
and
pickup
.
Six
Selectable
Groups
of
Settings
and
Logic
The
relay
stores
six
setting
groups
.
Select
the
active
setting
group
by
contact
input
or
command
.
Use
these
setting
groups
to
cover
a
wide
range
of
distribution
bus
protection
contingencies
.
Selectable
setting
groups
make
the
SEL
-
251
C
-
1
Relay
ideal
for
applications
requiring
frequent
setting
changes
.
Introduction
SEL
-
251
C
-
1
Instruction
Manual
1
-
2
Date
Code
20000515
Courtesy of NationalSwitchgear.com

Circuit
Breaker
Monitor
Tracks
Breaker
Performance
and
Helps
Maintenance
Planning
Separate
circuit
breaker
trip
counters
differentiate
and
tally
relay
-
initiated
trips
and
external
trips
.
Running
sums
of
interrupted
current
for
relay
and
external
trips
indicate
breaker
wear
on
a
pole
-
by
-
pole
basis
.
Use
these
data
to
schedule
breaker
maintenance
.
Trip
failure
logic
provides
alarm
and
breaker
failure
functions
.
A
close
failure
alarm
indi
-
cates
circuit
breaker
closing
circuit
or
mechanism
problems
.
The
trip
circuit
monitor
detects
abnormal
open
or
short
circuits
in
the
circuit
breaker
tripping
circuit
or
status
input
.
Analyze
Operations
Using
Event
Reports
Eleven
-
cycle
event
reports
triggered
by
user
selected
conditions
provide
the
current
,
voltage
,
and
sequence
-
of
-
events
information
you
need
to
understand
relay
and
circuit
breaker
perfor
-
mance
,
as
well
as
stress
on
the
protected
system
for
every
fault
.
Comprehensive
Metering
Supports
Protection
.
Operation
,
and
Demand
Analysis
The
relay
measures
phase
and
zero
-
sequence
voltage
and
current
,
as
well
as
MW
and
MVAR
.
Demand
and
peak
demand
values
for
current
,
MW
,
and
MVAR
are
also
available
.
Metering
also
supports
protection
,
because
you
can
inspect
the
quantities
monitored
by
relay
elements
.
Check
for
load
encroachment
and
unbalance
through
instantaneous
,
demand
,
and
peak
-
demand
measurements
.
Access
SEL
-
251
C
-
1
Relay
Information
Via
the
SEL
-
KD
Relay
Display
You
can
connect
up
to
four
SEL
-
251
C
-
1
Relays
to
one
SEL
-
RD
Relay
Display
.
Access
relay
target
,
meter
,
status
,
fault
history
,
and
circuit
breaker
information
via
the
relay
display
.
You
can
even
change
the
active
setting
group
via
the
display
.
Date
Code
20000515
Introduction
SEL
-
251
C
-
1
Instruction
Manual
1
-
3
Courtesy of NationalSwitchgear.com

Courtesy of NationalSwitchgear.com

SPECIFICATIONS
TABLE
OF
CONTENTS
2
-
1
General
Specifications
Functional
Specifications
SEL
-
251
C
-
1
Relay
SELOGIC
*
Control
Equations
Targets
Selectable
Setting
Groups
Circuit
Breaker
Monitor
Metering
Serial
Interfaces
Self
-
Tests
IRIG
-
B
Input
Description
Signal
Processing
Torque
Control
Demand
Ammeters
Event
Report
Time
-
Overcurrent
Element
Curve
-
Timing
and
Time
Delay
Reset
Equations
2
-
4
2
-
8
2
-
14
2
-
15
2
-
16
2
-
16
2
-
16
2
-
17
2
-
19
2
-
19
2
-
20
2
-
23
2
-
24
2
-
25
TABLES
2
-
8
Trip
Circuit
Monitor
Alarm
(
TCMA
)
Truth
Table
SEL
-
251
C
-
1
Relay
Word
Setting
Group
Selection
Input
Truth
Table
Power
Supply
Self
-
Test
Limits
Self
-
Test
Summary
TCI
Settings
Table
2.1
Table
2.2
Table
2.3
Table
2.4
Table
2.5
Table
2.6
2
-
11
2
-
15
2
-
17
2
-
19
2
-
21
Table
of
Contents
SEL
-
251
C
-
1
Instruction
Manual
Date
Code
20000515
1
Courtesy of NationalSwitchgear.com

FIGURES
Figure
2.1
:
SEL
-
251
C
-
1
Relay
Inputs
,
Outputs
,
and
Targets
Diagram
.
.
.
Figure
2.2
:
Time
Delayed
52
A
and
52
B
Functions
Figure
2.3
:
Trip
Circuit
Monitor
(
TCM
)
DC
Voltage
Connections
Figure
2.4
:
Trip
Circuit
Monitor
Alarm
(
TCMA
)
Logic
Figure
2.5
:
SEL
-
251
C
-
1
Relay
SELOGIC
Control
Equations
Block
Diagram
Figure
2.6
:
Relay
Word
Bit
Realizations
Figure
2.7
:
Relay
Word
Bit
Realization
Figure
2.8
:
SEL
-
251
C
-
1
Relay
Front
Panel
Target
LEDs
Figure
2.9
:
Distribution
Transformer
Bank
Protected
by
High
-
Side
Fuses
.
Figure
2.10
:
Moderately
Inverse
Curves
Figure
2.11
:
Inverse
Curves
Figure
2.12
:
Very
Inverse
Curves
Figure
2.13
:
Extremely
Inverse
Curves
Figure
2.14
:
SEL
-
251
C
-
1
Phase
Overcurrent
Logic
Diagrams
Figure
2.15
:
SEL
-
251
C
-
1
Ground
/
Residual
Overcurrent
Logic
Diagrams
.
.
Figure
2.16
:
SEL
-
251
C
-
1
Overcurrent
and
Undervoltage
Elements
Figure
2.17
:
SEL
-
251
C
-
1
Overcurrent
and
Distance
Elements
Figure
2.18
:
SEL
-
251
C
-
1
Transformer
Fuse
-
Blown
Detection
Logic
Figure
2.19
:
SEL
-
251
C
-
1
Demand
Ammeters
Figure
2.20
:
SEL
-
251
C
-
1
Programmable
Trip
Logic
Diagram
Figure
2.21
:
SEL
-
251
C
-
1
Close
Logic
Diagram
2
-
4
2
-
7
2
-
7
2
-
8
2
-
10
2
-
12
2
-
13
2
-
14
2
-
22
2
-
26
2
-
26
2
-
26
2
-
26
2
-
27
2
-
28
2
-
29
2
-
30
2
-
31
2
-
32
2
-
33
2
-
33
Table
of
Contents
SEL
-
251
C
-
1
Instruction
Manual
Date
Code
20000515
n
Courtesy of NationalSwitchgear.com

SECTION
2
:
SPECIFICATIONS
GENERAL
SPECIFICATIONS
120
V
nominal
phase
-
to
-
neutral
,
three
-
phase
,
four
-
wire
connection
(
150
V
phase
-
to
-
neutral
saturation
limit
)
Voltage
Inputs
5
A
nominal
15
A
continuous
Current
Inputs
110
A
saturation
limit
500
A
1
-
second
thermal
rating
60
Hz
Frequency
and
Rotation
ABC
Per
IEC
255
-
0
-
20
:
1974
,
using
the
simplified
method
of
assessment
6
A
continuous
carry
30
A
make
per
IEEE
C
37.90
:
1989
100
A
for
one
second
Output
Contacts
270
Vac
/
360
Vdc
MOV
for
differential
surge
protection
.
Pickup
/
dropout
time
:
<
5
ms
Breaking
Capacity
(
L
/
R
=
40
ms
)
:
0.5
A
0.3
A
0.2
A
Cyclic
Capacity
(
L
/
R
=
40
ms
)
:
0.5
A
0.3
A
0.2
A
48
V
10
,
000
operations
10
,
000
operations
10
,
000
operations
125
V
250
V
2.5
cycles
per
second
2.5
cycles
per
second
2.5
cycles
per
second
The
following
optoisolated
inputs
draw
4
mA
when
nominal
control
voltage
is
applied
:
24
Vdc
15
-
30
Vdc
48
Vdc
:
30
-
60
Vdc
250
Vdc
:
150
-
300
Vdc
Fixed
"
Level
-
Sensitive
"
inputs
are
provided
on
relays
with
125
Vdc
optoisolated
inputs
.
The
125
Vdc
optoisolated
input
each
draw
6
mA
when
nominal
voltage
is
applied
.
The
inputs
operate
as
shown
below
:
125
Vdc
:
on
for
100
-
150
Vdc
;
off
below
75
Vdc
48
V
125
V
250
V
Optoisolated
Inputs
24
/
48
Volt
:
20
-
60
Vdc
;
125
/
250
Volt
:
85
-
350
Vdc
or
85
-
264
Vac
10
watts
nominal
,
14
watts
maximum
(
all
output
relays
energized
)
Power
Supply
Two
EIA
-
232
serial
communications
ports
,
Port
2
of
the
SEL
-
251
C
-
1
Relay
has
front
-
and
rear
-
panel
connectors
.
See
Figure
6.3
.
Relay
accepts
demodulated
IRIG
-
B
time
code
input
Available
in
horizontal
and
vertical
mounting
configurations
V
,
I
inputs
:
2500
Vac
for
10
seconds
Other
:
3000
Vdc
for
10
seconds
(
excludes
EIA
-
232
)
Routine
Tested
.
Communications
Dimensions
Time
Code
Input
Mounting
Dielectric
Strength
Date
Code
20000515
Specifications
SEL
-
251
C
-
1
Instruction
Manual
2
-
1
Courtesy of NationalSwitchgear.com

Operating
Temperature
-
40
°
to
158
°
F
(
-
40
°
to
70
°
C
)
Environmental
IEEE
C
37.90
-
1989
Type
Tests
IEEE
Standards
for
Relays
and
Relay
Systems
Associated
with
Electrical
Power
Apparatus
,
Section
8
:
Dielectric
Tests
Severity
Level
:
2500
Vac
on
analog
inputs
;
3000
Vdc
on
power
supply
,
contact
inputs
and
contact
outputs
IEEE
C
37.90
.
1
-
1989
IEEE
Standard
Surge
Withstand
Capability
(
SWC
)
Tests
for
Protective
Relays
and
Relay
Systems
Severity
Level
:
3.0
kV
oscillatory
,
5.0
kV
fast
transient
IEEE
C
37.90
.
2
(
Issued
for
trial
use
December
1987
)
IEEE
Trial
-
Use
Standard
,
Withstand
Capability
of
Relay
Systems
to
Radiated
Electromagnetic
Interference from
Transceivers
Severity
Level
:
lOV
/
m
Exceptions
:
5.5
.
2
(
2
)
Performed with
200
frequency
steps
per
octave
Digital
Equipment
Modulation
Test
not
performed
Test
signal
turned
off
between
frequency
steps
to
simulate
keying
IEC
68
-
2
-
1
Fifth
Edition
-
1990
Environmental
testing
,
Part
2
:
Tests
-
Test
Ad
:
Cold
Severity
Level
:
16
hours
at
-
40
°
C
IEC
68
-
2
-
2
Fourth
Edition
-
1974
Environmental
testing
,
Part
2
:
Tests
-
Test
Bd
:
Dry
heat
Severity
Level
:
16
hours
at
+
85
°
C
IEC
68
-
2
-
30
Second
Edition
-
1980
Basic
environmental
testing
procedures
,
Part
2
:
Tests
-
Test
Db
and
guidance
:
Damp
heat
,
cyclic
(
12
+
12
-
hour
cycle
)
Severity
Level
:
55
°
C
,
6
cycles
5.5
.
3
5.5
.
4
IEC
255
-
5
First
Edition
-
1977
Electrical
relays
,
Part
5
:
Insulation
tests
for
electrical
relays
,
Section
6
:
Dielectric
Tests
Severity
Level
:
Series
C
(
2500
Vac
on
analog
inputs
;
3000
Vdc
on
power
supply
,
contact
inputs
and
contact
outputs
)
Section
8
:
Impulse
Voltage
Tests
Severity
Level
:
0.5
Joule
,
5000
volt
IEC
255
-
21
-
1
First Edition
-
1988
Electrical
relays
,
Part
21
:
Vibration
,
shock
,
bump
,
and
seismic
tests
on
measuring
relays
and
protection
equipment
,
Section One
-
Vibration
tests
(
sinusoidal
)
Severity
Level
:
Class
1
2
-
2
Specifications
SEL
-
251
C
-
1
Instruction
Manual
Date
Code
20000515
Courtesy of NationalSwitchgear.com

IEC
255
-
21
-
2
First
Edition
-
1988
Electrical
relays
,
Part
21
:
Vibration
,
shock
,
bump
,
and
seismic
tests
on
measuring
relays
and
protection
equipment
,
Section
Two
-
Shock
and
bump
tests
Severity
Level
:
Class
1
IEC
255
-
22
-
1
First
Edition
-
1988
Electrical
disturbance
tests
for
measuring
relays
and
protection
equipment
,
Part
1
:
1
MHz
burst
disturbance
tests
Severity
Level
:
2.5
kV
peak
common
mode
,
1.0
kV
peak
differential
mode
IEC
255
-
22
-
3
-
1989
Electrical
relays
,
Part
22
:
Electrical
disturbance
tests
for
measuring
relays
and
protection
equipment
,
Section
Three
-
Radiated
electromagnetic
field
disturbance
tests
Exceptions
:
4.3
.
2.2
Frequency
sweep
approximated
with
200
frequency
steps
per
octave
IEC
801
-
2
Second
Edition
-
1991
-
04
Electromagnetic
compatibility
for
industrial
-
process
measurement
and
control
equipment
,
Part
2
:
Electrostatic
discharge
requirements
Severity
Level
:
3
IEC
801
-
3
Electromagnetic
compatibility
for
industrial
process
measurement
and
control
equipment
,
Part
3
:
Radiated
electromagnetic
field
requirements
Severity
Level
:
lOV
/
m
Exceptions
:
Frequency
sweep
approximated
with
200
frequency
steps
per
octave
.
IEC
801
-
4
First
Edition
-
1988
Electromagnetic
compatibility
for
industrial
process
measurements
and
control
equipment
,
Part
4
:
Electrical
fast
transient
/
burst
requirements
Severity
Level
:
4
(
4
kV
on
power
supply
,
2
kV
on
inputs
and
outputs
)
9.1
Unit
Weight
12
pounds
(
5.5
kg
)
Date
Code
20000515
Specifications
SEL
-
251
C
-
1
Instruction
Manual
2
-
3
Courtesy of NationalSwitchgear.com

1
TRIP
IN
1
1 7
2
18
3
IN
2
19
TRIP
APPLY
CONTROL
VOLTAGE
TO
OPTOISOLATED
INPUTS
TO
ASSERT
4
20
>
5
IN
3
21
CLOSE
6
22
23
IN 4
7
A
1
CAN
BE
CONFIGURED
AS
EITHER
FORM
”
A
"
OR
”
B
”
OUTPUT
CONTACTS
24
8
<
25
1
N
5
9
A
2
26
10
27
IN
6
1 1
28
A
3
12
13
29
A 4
IA
14
30
31
15
IB
ALARM
32
16
33
IC
34
AUX
INPUT
DEMODULATED
IRIG
-
B
VA
37
VB
38
39
-
T
^
rru
,
vc
PORT
1
N
40
EIA
-
232
300
-
9600
BAUD
>
PORT
2
R
PORTS
IN
PARALLEL
(
PORT
2
F
HAS
PRIORITY
)
+
POWER
SUPPLY
<
44
PORT
2
F
(
FRONT
PANEL
)
45
CHASSIS
GROUND
46
TARGET
LEDs
BKR
EN
ALRM
INST
A
B
C G
oooooooo
TARGET
RESET
FAULT
TYPE
STATUS
DWG
.
1026
-
i
02
c
Figure
2.1
:
SEL
-
251
C
-
1
Relay
Inputs
,
Outputs
,
and
Targets
Diagram
FUNCTIONAL
SPECIFICATIONS
Phase
Overcurrent
Elements
for
Phase
and
Three
-
Phase Faults
-
See
Figures
2.14
,
2.16
,
and
2.17
Phase
Time
-
Overcurrent
Element
51
T
Curve
families
:
moderately
inverse
,
inverse
,
very
inverse
,
extremely
inverse
Time dial
:
0.5
to
15.00
in
0.01
steps
.
Pickup
(
51
P
)
:
1
to
12
A
±
2
%
of
setting
±
0.1
A
secondary
Time
delay
or
1
-
cycle
reset
time
Timing
:
±
5
%
and
±
1
cycle
for
currents
between
2
and
20
multiples
of
pickup
Specifications
SEL
-
251
C
-
1
Instruction
Manual
Date
Code
20000515
2
-
4
Courtesy of NationalSwitchgear.com