GE SPA11A User manual

GEK
-
65512
F
INSTRUCTIONS
STATIC
PILOT
WIRE
MONITORING
RELAY
TYPES
:
SPA
11
A
SPA
11
B
SPA
12
A
SPA
12
B
GE
Protection
and
Control
205
Great
Valley
Parkway
Malvern
,
PA
19355
-
1337
Courtesy of NationalSwitchgear.com

GEK
-
65512
CONTENTS
PAGE
INTRODUCTION
APPLICATION
OPTIONS
AND
FEATURES
RATINGS
TEMPERATURE
DIELECTRIC
STRENGTH
CONTACTS
TARGET
SEAL
-
IN
UNIT
SEISMIC
CAPABILITY
CHARACTERISTICS
OPERATING
PRINCIPLES
OPEN
PILOT
WIRES
SHORTED
PILOT
WIRES
GROUNDED
PILOT
WIRES
OPERATING
TIMES
TRANSFER
TRIP
LOW
PASS
FILTER
BURDENS
SETTINGS
CONSTRUCTION
RECEIVING
,
HANDLING
AND
STORAGE
ACCEPTANCE
TESTS
VISUAL
INSPECTION
MECHANICAL
INSPECTION
CRADLE
AND
CASE
BLOCKS
TARGET
SEAL
-
IN
UNIT
(
SPA
11
B
AND
12
B
)
TELEPHONE
RELAYS
ELECTRICAL
INSPECTION
250
DC
RATING
SENDING
END
UNDERCURRENT
DETECTION
(
SPA
11
A
AND
11
B
)
OVERCURRENT
DETECTION
(
SPA
11
A
AND
11
B
)
GROUND
DETECTION
(
SPA
11
A
AND
11
B
)
TRANSFER
TRIP
(
SPA
11
B
)
RECEIVING
END
UNDERCURRENT
DETECTION
(
SPA
12
A
AND
12
B
)
TRANSFER
TRIP
(
SPA
12
B
)
DIELECTRIC
TESTS
(
HIGH
POTENTIAL
TESTS
)
INTRODUCTION
HIPOT
TESTS
RESTORING
RELAY
TO
SERVICE
INSTALLATION
PROCEDURE
SETTING
THE
TAP
OF
THE
TARGET
SEAL
-
IN
UNIT
(
SPA
11
B
AND
12
B
)
SUPPLY
VOLTAGE
SETTING
TERMINAL
ARRANGEMENT
SETTING
PERIODIC
CHECKS
AND
ROUTINE
MAINTENANCE
CONTACTS
ELECTRICAL
TESTS
SERVICING
TELEPHONE
RELAYS
TARGET
SEAL
-
IN
UNIT
RENEWAL
PARTS
LIST
OF
ILLUSTRATIONS
3
3
4
5
5
5
5
5
6
6
6
7
7
7
7
8
9
9
9
10
12
12
13
13
13
13
13
13
14
14
14
14
14
14
15
15
15
15
15
16
17
17
17
17
17
18
18
18
19
19
19
19
21
2
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GEK
-
65512
STATIC
PILOT
WIRE
MONITORING
RELAY
TYPES
:
SPA
11
A
SPA
11
B
SPA
12
A
SPA
12
B
INTRODUCTION
The
Type
SPA
static
pilot
-
wire
-
monitoring
relays
are
designed
for
use
in
conjunction
with
an
SPD
pilot
-
wire
system
to
provide
detection
of
open
,
shorted
,
reversed
or
grounded
pilot
wires
.
The
relays
are
powered
by
a
dual
-
rated
,
self
-
contained
,
isolated
DC
-
to
-
DC
power
supply
,
to
reduce
the
possibility
of
battery
grounds
interfering
with
operation
of
the
pilot
-
wire
scheme
.
Models
are
available
with
48
/
110
-
125
volt
DC
ratings
.
The
Type
SPA
11
A
and
SPA
12
A
relays
provide
the
basic
pilot
-
wire
-
monitoring
functions
.
The
SPA
11
A
is
the
sending
-
end
relay
and
operates
in
conjunction
with
a
Type
SPA
12
A
receiving
-
end
relay
at
the
remote
terminal
(
or
terminals
)
of
two
(
or
three
)
terminal
lines
.
These
relays
will
close
contacts
and
operate
a
light
-
emitting
diode
(
LED
)
when
an
abnormal
pilot
-
wire
condition
is
detected
.
The
Type
SPA
11
B
and
SPA
12
B
relays
include
provisions
for
the
transmission
and
reception
of
direct
transfer
-
trip
signals
in
either
direction
,
as
well
as
the
basic
pilot
-
wire
-
monitoring
functions
.
The
SPA
monitoring
scheme
uses
a
low
-
level
DC
signal
in
order
to
avoid
interfering
with
the
primary
AC
pilot
wire
signal
(
SPD
relays
)
.
Within
the
SPA
relays
,
the
DC
monitoring
signal
is
separated
from
the
AC
signal
by
low
-
pass
filters
.
SPA
models
are
available
for
use
with
50
hertz
and
60
hertz
SPD
relays
.
The
Types
SPA
11
A
,
SPA
11
B
,
SPA
12
A
and
SPA
12
B
are
each
packaged
in
the
S
2
drawout
case
,
the
outline
and
panel
drilling
of
which
is
shown
in
Figure
11
.
APPLICATION
The
Type
SPA
static
relays
are
intended
for
application
as
pilot
-
wire
-
monitoring
relays
and
/
or
transfer
-
trip
relays
.
As
noted
above
,
they
are
designed
specifically
for
use
with
the
SPD
pilot
-
wire
relaying
system
.
When
only
the
monitoring
function
is
desired
,
the
Type
SPA
11
A
is
required
at
one
end
of
the
pilot
circuit
,
designated
as
the
sending
end
;
and
the
Type
SPA
12
A
is
required
at
the
remote
receiving
end
,
or
at
both
remote
ends
in
the
case
of
a
three
-
terminal
line
.
The
SPA
11
A
relay
at
the
sending
end
circulates
a
low
-
level
DC
current
around
the
pilot
loop
,
which
holds
the
contacts
of
the
undercurrent
(
UC
)
functions
in
both
the
sending
-
end
and
These
instructions
do
not
purport
to
cover
all
details
or
variations
in
equipment
nor
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
General
Electric
Company
.
To
the
extent
required
the
products
described
herein
meet
applicable
ANSI
,
IEEE
and
NEMA
standards
;
but
no
such
assurance
is
given
with
respect
to
local
codes
and
ordinances
because
they
vary
greatly
.
3
Courtesy of NationalSwitchgear.com

GEK
-
65512
receiving
-
end
relays
in
the
open
position
.
An
open
pilot
wire
will
result
in
the
closure
of
the
UC
contacts
and
operation
of
the
UC
LED
at
both
the
sending
and
receiving
ends
.
A
shorted
pilot
wire
,
resulting
in
a
significant
increase
in
the
monitoring
current
,
will
result
in
closure
of
the
contacts
of
the
overcurrent
(
OC
)
function
and
operation
of
the
OC
LED
in
the
sending
-
end
relay
,
and
the
closure
of
the
UC
function
contacts
at
the
receiving
end
.
A
grounded
pilot
-
wire
circuit
will
result
in
closure
of
the
contacts
of
the
ground
-
detection
function
and
operation
of
the
ground
-
indicating
LED
in
the
sending
-
end
relay
Specific
information
on
the
magnitude
of
the
circulating
current
,
and
operating
levels
of
the
UC
,
OC
and
ground
-
detection
functions
,
is
provided
in
the
section
on
CHARACTERISTICS
.
Elementary
diagrams
for
the
two
-
terminal
and
three
-
terminal
applica
-
tions
of
the
SPA
11
A
and
SPA
12
A
relays
are
provided
in
Figures
20
and
21
respectively
.
When
direct
transfer
tripping
over
the
pilot
wire
is
desired
,
in
addition
to
the
monitoring
functions
,
the
SPA
11
B
is
required
at
the
sending
end
and
the
SPA
12
B
at
the
receiving
end
.
These
"
B
"
relays
include
the
necessary
circuits
to
transmit
and
receive
the
direct
transfer
-
trip
signals
,
as
well
as
the
functions
required
to
monitor
the
pilot
-
wire
circuit
as
previously
described
.
Typical
elementary
diagrams
for
a
pilot
-
wire
relaying
system
with
monitoring
and
transferred
tripping
are
provided
in
Figure
22
for
two
-
terminal
lines
and
in
Figure
23
for
three
-
terminal
line
applications
.
These
diagrams
illustrate
the
two
-
way
transfer
-
trip
application
in
which
the
transfer
-
trip
signal
is
initiated
by
either
the
sending
-
end
relay
(
SPA
11
B
)
or
the
receiving
-
end
relay
(
SPA
12
B
)
.
When
the
transfer
-
trip
signal
is
to
be
sent
in
one
direction
only
,
the
same
relays
are
applied
but
the
TT
unit
would
not
be
used
at
the
transfer
-
trip
initiating
end
and
the
TTA
unit
would
not
be
Diagrams
for
tne
one
-
way
transfer
-
trip
application
used
at
the
transfer
-
trip
receiving
end
.
are
available
upon
request
.
OPTIONS
AND
FEATURES
There
are
four
types
of
SPA
relays
:
1
)
a
sending
-
end
relay
,
2
)
a
sending
-
end
relay
with
transfer
-
trip
capability
,
3
)
a
receiving
-
end
relay
,
and
4
)
a
receiving
-
end
relay
with
transfer
-
trip
capability
.
A
sending
-
end
relay
with
the
transfer
-
trip
feature
may
be
used
with
a
receiving
-
end
relay
without
the
transfer
-
trip
feature
and
vice
versa
.
The
basic
functions
of
the
four
types
of
SPA
relays
are
outlined
in
the
table
below
.
TABLE
I
FUNCTIONS
OF
THE
SPA
RELAYS
SENDING
RECEIVING
TRANSFER
TRIP
CAPABILITY
UNDERCURRENT
DETECTION
OVERCURRENT
GROUND
DETECTION
DETECTION
RELAY
END
END
SPA
11
A
SPA
11
B
SPA
12
A
SPA
12
B
X
X
X
X
XXX
X
X
X
X
X
XX
4
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GEK
-
65512
An
open
pilot
wire
will
result
in
undercurrent
detection
;
a
shorted
pilot
wire
will
result
in
overcurrent
detection
,
and
ground
on
either
conductor
of
the
pilot
wire
will
result
in
ground
detection
.
RATINGS
TEMPERATURE
These
relays
have
been
designed
for
continuous
operation
in
ambient
temperatures
between
-
20
oC
and
+
55
°
C
per
ANSI
Standard
C
37.90
-
1978
.
Over
this
range
,
the detection
levels
will
vary
by
not
more
than
three
percent
(
3
%
)
from
their
nominal values
at
20
<
>
C
.
In
addition
,
these
relays
will
not
malfunction
nor
be
damaged
if
operated
in
an
ambient
up
to
65
°
C
.
DIELECTRIC
STRENGTH
(
AC HIGH
-
POTENTIAL
TEST
)
For
the
purposes
of
dielectric
tests
,
the
SPA
relays
are
rated
600
volts
.
Per
ANSI
/
IEEE
C
37.90
-
1978
,
the
high
-
potential
test
voltage
is
2200
volts
AC
for
one
minute
.
As
described
in
the standard
,
relays
other than
new
should be
tested
at
75
%
of
this
voltage
.
CONTACTS
The
telephone
-
relay
output
contacts
in
the
SPA
will
make and
carry
30
amperes
for
tripping
duty
and
will
make and
carry
3
amperes
continuously
.
The
interrupting ratings
are
given
in
Table
II
.
TABLE II
INTERRUPTING
CURRENT
RATINGS
OF TELEPHONE
-
TYPE
RELAY
CONTACTS
AMPS
AC
VOLTS
INDUCTIVE
t
NON
-
INDUCTIVE
115
0.75
2.0
230
0.5
1.5
DC
VOLTS
48
1.0
3.0
125
0.5
1.5
250
0.25
1.0
t
The
inductive
rating
is
based
on an
L
/
R
ratio
of
0.1
second
.
5
Courtesy of NationalSwitchgear.com

GEK
-
65512
TARGET
SEAL
-
IN
UNIT
The
target
seal
-
in
unit
connected
to
studs
1
and
11
in
the
SPA
11
B
and
SPA
12
B
relays
has
the
ratings
and
characteristics
shown
in
Table
III
.
TABLE
III
RATINGS
AND
CHARACTERISTICS
OF
THE
TARGET
SEAL
-
IN
UNIT
TAP
0.2
2.0
DC
Resistance
jf
.
10
%
(
Ohms
)
Minimum
Operating
(
Amperes
)
Carry
Continuously
(
Amperes
)
Carry
30
Amps
for
(
Seconds
)
Carry
10
Amps
for
(
Seconds
)
60
Hz
Impedance
(
Ohms
)
Minimum
Dropout
(
Amperes
)
7
0.13
0.2
2.0
0.3
3
0.03
4
0.25
30
52
0.53
0.05
0.5
SEISMIC
CAPABILITY
The
Seismic
Fragility
Level
exceeds
3.5
g
ZPA
when
tested
using
a
biaxial
multi
-
frequency
input
motion
to
produce
a
Required
Response
Spectrum
in
accordance
with
ANSI
/
IEEE
C
37.98
-
1978
,
Standard
for
SeismicTesting
of
Relays
.
CHARACTERISTICS
OPERATING
PRINCIPLES
The
Type
SPA
relays
are
designed
to
detect
an
open
pilot
-
wire
,
a
shorted
pilot
wire
,
and
a
grounded
pilot
wire
in
a
protective
system
using
pilot
-
wire
relays
.
Type
SPD
pilot
-
wire
relays
are
covered
by
instruction
book
GEK
-
49794
.
The
Type
SPA
relays
operate
by
circulating
a
small
direct
current
of
approximately
0.75
milliamperes
through
the
pilot
wire
.
The
current
is
provided
by
the
power
supply
of
the
sending
-
end
monitoring
relay
(
SPA
11
A
or
SPA
11
B
)
.
The
receiving
-
end
monitoring
relay
(
s
)(
SPA
12
A
or
SPA
12
B
)
completes
the
circuit
loop
for
the
circulating
current
without
adding
or
subtracting
(
sourcing
or
sinking
)
any
current
.
OPEN
PILOT
WIRES
The
undercurrent
units
in
the
SPA
relays
are
energized
(
or
picked
up
)
under
normal
operating
conditions
.
When
an
open
circuit
of
the
pilot
wire
occurs
,
the
current
drops
to
zero
and
the
undercurrent
units
in
both
receiving
-
and
sending
-
end
relays
drop
out
and
the
UC
LED
indicators
light
.
This
is
the
extreme
case
of
the
undercurrent
condition
.
The
undercurrent
units
will
drop
out
forthe
circulating
currents
indicated
below
6
Courtesy of NationalSwitchgear.com

GEK
-
65512
TABLE
IV
UNDERCURRENT
DETECTION
LEVELS
RELAY
ARRANGEMENT
UNDERCURRENT
DETECTION
Sending
End
Receiving
End
Sending
End
Receiving
End
2
Terminal
2
Terminal
3
Terminal
3
Terminal
0.53
ma
or
less
0.43
ma
or
less
0.53
ma
or
less
0.21
ma
or
less
SHORTED
PILOT
WIRES
The
overcurrent
units
in
the
SPA
relays
are
normally
de
-
energized
(
or
dropped
out
)
.
When
a
short
circuit
of
the
pilot
wire
occurs
,
the
current
increases
significantly
,
causing
the
overcurrent
unit
in
the
sending
-
end
relay
to
pick
up
,
and
causing
the
OC
LED
indicator
to
light
.
All
the
current
circulates
through
the
short
circuit
,
thereby
reducing
the
current
at
the
receiving
end
(
s
)
to
zero
.
This
is
detected
by
the
undercurrent
unit
in
the
receiving
-
end
relay
(
s
)
.
A
short
circuit
is
the
extreme
case
of
the
overcurrent
condition
.
The
overcurrent
unit
of
the
sending
-
end
relay
will
pick
up
for
circulating
currents
of
1.35
milliamperes
or
greater
.
GROUNDED
PILOT
WIRES
When
the
resistance
-
to
-
ground
of
either
conductor
of
the
pilot
wire
falls
below
10
,
000
ohms
,
the
ground
unit
on
the
sending
-
end
relay
(
normally
dropped
out
)
will
pick
up
and
the
GND
indicator
LED
will
light
.
REVERSED
PILOT
WIRES
In
the
event
that
the
conductors
of
the
pilot
wire
are
accidentally
reversed
,
the
circulating
current
is
shunted
through
a
low
-
resistance
path
in
the
receiving
-
end
relay
.
This
results
in
overcurrent
detection
by
the
sending
-
end
relay
and
undercurrent
detection
by
the
receiving
-
end
relay
.
This
condition
is
the
same
as
in
the
case
of
shorted
pilot
wires
.
OPERATING
TIMES
The
operating
times
of
the
undercurrent
,
overcurrent
and
ground
detection
circuits
were
intentionally
made
slow
in
order
to
override
transient
disturbances
.
The
operating
times
vary
,
depending
upon
conditions
on
the
primary
system
,
application
arrangements
(
e
.
g
.
,
two
terminals
versus
three
terminals
)
,
and
the
extent
of
the
abnormal
condition
on
the
pilot
wire
.
The
values
in
Table
V
are
approximate
.
They
are
intended
to
give
a
general
idea
of
the
time
involved
.
7
Courtesy of NationalSwitchgear.com

GEK
-
65512
TABLE
V
APPROXIMATE
OPERATING
TIMES
UNIT
PILOT
WIRE
CONDITION
DETECTION
TIME
t
RESTORE
TIME
tt
UC
Open
Circuit
Short
Circuit
Grounded
Conductor
BOO
msec
.
300
msec
.
300
to
500
msec
.
2000
msec
.
700
to
2000
msec
.
400
to
800
msec
.
OC
GND
Detection
time
of
each
function
is
the
time
to
close
its
contact
upon
the
occurrence
of
the
condition
listed
in
the
table
.
Restore
time
for
each
function
is
the
time
to
reopen
its
contact
when
the
condition
listed
in
the
table
is
removed
and
normal
circuit
conditions
are
restored
.
t
tt
TRANSFER
TRIP
The
SPA
11
B
and
SPA
12
B
relays
can
send
a
transfer
-
trip
signal
over
the
pilot
wire
to
initiate
tripping
at
the
other
terminal
(
s
)
.
The
signal
can
be
sent
from
either
the
sending
-
end
relay
(
SPA
11
B
)
orthe
receiving
-
end
relay
(
SPA
12
B
)
.
It
will
initiate
the
tripping
of
both
the
local
and
remote
breakers
on
a
two
-
terminal
line
,
or
of
all
three
breakers
on
a
three
-
terminal
line
.
The
transfer
-
trip
signal
is
produced
by
energizing
the
coil
of
the
TTA
unit
through
an
external
contact
.
When
the
TTA
picks
up
,
it
reverses
the
polarity
of
the
DC
voltage
applied
to
the
pilot
wire
through
studs
7
and
8
.
The
reversed
-
polarity
voltage
on
the
pilot
wire
causes
the
operation
of
the
transfer
-
trip
(
TT
)
unit
in
the
local
and
remote
SPA
relays
.
The
TT
output
contact
connected
between
studs
1
and
11
is
provided
with
a
target
seal
-
in
unit
and
is
recommended
for
tripping
duty
.
The
TT
contact
between
studs
2
and
3
is
an
auxiliary
contact
and
has
no
target
seal
-
in
unit
.
The
operating
time
between
energizing
TTA
at
one
end
of
the
pilot
wire
and
picking
up
TT
at
the
other
end
(
remote
)
varies
slightly
with
the
length
of
the
pilot
wire
,
as
indicated
below
.
The
time
to
pick
up
the
local
unit
is
approximately
two
(
2
)
cycles
,
independent
of
the
length
of
the
pilot
wire
.
Remote
TT
Pickup
Time
Remote
TT
Dropout
Time
(
60
Hertz
Basis
)
(
60
Hertz
Basis
)
Short
Pilot
Wire
(
Series
R
=
0
ohm
)
Long
Pilot
Wire
(
Series
R
=
2000
ohms
)
approximately
4
cycles
approximately
6
cycles
approximately
5
cycles
approximately
6
cycles
8
Courtesy of NationalSwitchgear.com

GEK
-
65512
If
the
pilot
wire is
to
be used
only
for
the
transfer
trip
function
and
no
pilot
-
wire
-
differential
relays
are
connected
to
the
pilot
wire
,
the
operating
time
will
be
as
follows
:
Remote
TT
Pickup
Time
(
60
Hertz
Basis
)
approximately
2
cycles
approximately
3
cycles
Short
Pilot
Wire
Long
Pilot
Wire
The
transfer
-
trip
operating
time is
virtually
independent
of
station
battery
voltage
for
two
reasons
:
1
)
the
TT
units
are
energized
from
the
regulated
12
volt
power
supply
in
the
relay
;
and
2
)
the
operating
time
of
theTTA
units varies
only
slightly
with
battery
voltage
,
as
shown
in
Fig
.
12
.
LOW
PASS
FILTER
The
current
circulating through
the
pilot
wire is
monitored
through
a
low
-
pass
filter
in
each
of
the
SPA
relays
.
The
filter
serves
two
purposes
:
1
)
it
screens
out
the
AC
signals
transmitted
over
the
pilot
wire
by
the
SPD
relays
;
and
2
)
it
screens
out
any
AC
disturbances
or
"
noise
"
on
the
pilot
wire
.
Relay
models
are
available
for
use on
50
hertz
systems
and
60
hertz
systems
.
The
filters
are
slightly
different
,
to
ensure
adequate
attenuation
at
the
system
frequency
.
BURDENS
The
table
below
indicates
the
burdens
of
the
SPA
relays
on
the
DC
station
supply
under
normal
operating
conditions
.
TABLE
VI
DC
BURDENS
WITH TTA
ENERGIZED
48
V
110
V
125
V
48
V
110
V
125
V
SPA
11
A
SPA
11
B
SPA
12
A
SPA
12
B
60
ma
60
ma
60
ma
60
ma
25
ma
25
ma
25
ma
25
ma
30
ma
30
ma
30
ma
30
ma
150
ma
80
ma
90
ma
150
ma
80
ma
90
ma
Values
may vary
by
up
to
30
%
SETTINGS
The
SPA
relays
were
designed
and
are
factory
tested
such
that
calibration
by
the
user
is
unnecessary
.
There
are
no
adjustments
to
be
made
.
The
power
supplies
within
the
relay
must
be
set
by
the
user
to
correspond
with
the
DC
input
voltage
.
This
entails
the
positioning
of
two
adjacent
selectors
on
the
printed
-
circuit
board that
contains
the
power
supply
.
The
positions
are
clearly
labeled
on
the
printed
-
circuit
board
.
The
relays
that
include
the
transfer
trip
feature
(
SPA
11
B
and
12
B
)
contain
an
additional
voltage
link
to
be
set
.
It is
located
above the
target
seal
-
in
unit
on
the
mounting
plate
.
9
Courtesy of NationalSwitchgear.com

GEK
-
65512
The
receiving
-
end
relays
(
SPA
12
A
and
SPA
12
B
)
must
be
set
for
a
two
-
terminal
application
or
a
three
-
terminal
application
.
This
entails
the
positioning
of
a
selector
on
the
printed
-
circuit
board
.
The
target
seal
-
in
unit
tap
setting
should
satisfy
the
following
two
requirements
:
1
)
the
minimum
trip
-
circuit
current
should
be
enough
to
operate
the
target
seal
-
in
(
at
least
150
%
of
tap
is
recommended
)
;
and
2
)
the
target
seal
-
in
unit
resistance
on
the
tap
chosen
must
be
low
enough
so
that
the
required
trip
current
will
flow
.
CONSTRUCTION
The
Type
SPA
relays
are
assembled
in
the
small
-
size
,
double
-
ended
(
S
2
)
drawout
case
having
studs
at
both
top
and
bottom
ends
in
the
rear
for
external
connections
.
The
electrical
connections
between
the
relay
and
case
studs
are
through
stationary
molded
inner
and
outer
blocks
,
between
which
nests
a
removable
connection
plug
.
The
outer
blocks
attached
to
the
case
have
the
studs
for
the
external
connections
,
and
the
inner
blocks
have
the
terminals
for
the
internal
connections
.
The
four
types
of
SPA
relays
have
the
same
nameplate
,
which
is
shown
in
Figure
14
.
There
are
two
cutouts
for
the
LED
indicators
and
the
selector
pins
.
One
set
of
selector
pins
sets
the
DC
voltage
rating
,
and
the
other
selector
pin
sets
the
relay
for
two
-
or
three
-
terminal
line
applications
.
The
labels
between
the
cutouts
are
identical
for
all
four
types
of
SPA
relays
.
The
sending
-
end
relays
(
SPA
11
A
and
11
B
)
have
no
selector
pin
to
set
the
relay
for
two
-
or
three
-
terminal
applications
,
and
the
receiving
-
end
relays
(
SPA
12
A
and
12
B
)
have
no
OC
and
GND
indicator
LEDs
.
Every
circuit
in
the
drawout
case
has
an
auxiliary
brush
,
as
shown
in
Figure
13
,
to
provide
adequate
overlap
when
the
connecting
plug
is
withdrawn
or
inserted
.
Some
circuits
are
equipped
with
shorting
bars
(
see
internal
connections
in
Figures
1
,
2
,
3
,
and
4
)
.
The
relay
mechanism
is
mounted
in
a
steel
framework
called
the
cradle
,
and
is
a
complete
unit
with
all
leads
terminated
at
the
inner
blocks
.
This
cradle
is
held
firmly
in
the
case
with
a
latch
at
both
top
and
bottom
.
The
connection
plug
,
besides
making
the
electrical
connections
between
the
respective
blocks
of
the
cradle
and
case
,
also
locks
the
latch
in
place
.
The
cover
,
which
is
drawn
to
the
case
by
thumbscrews
,
holds
the
connection
plugs
in
place
.
On
the
relays
that
include
the
transfer
trip
feature
(
SPA
11
B
and
SPA
12
B
)
,
the
target
-
reset
mechanism
is
a
part
of
the
cover
assembly
.
The
relay
case
is
suitable
for
either
semiflush
or
surface
mounting
on
all
panels
up
to
two
inches
thick
,
and
appropriate
hardware
is
available
.
The
relay
is
shipped
with
hardware
suitable
for
mountinq
on
1
/
8
inch
steel
panels
.
Panel
thickness
,
if
other
than
1
/
8
inch
,
must
be
indicated
on
the
relay
order
to
ensure
that
proper
hardware
will
be
included
.
Outline
and
panel
drilling
is
shown
in
Figure
11
.
A
separate
testing
plug
can
be
inserted
in
place
of
the
connection
plug
to
test
the
relay
in
place
on
the
panel
,
either
from
its
own
source
of
current
and
voltage
,
or
from
other
sources
;
or
the
relay
can
be
drawn
out
and
replaced
by
another
that
has
been
tested
in
the
laboratory
.
10
Courtesy of NationalSwitchgear.com