ABB KS Manual

ABB Automation Inc.
Substation Automation and Protection Division
Coral Springs, FL 33065
Instruction Leaflet
All possible contingencies which may arise during installation, operation or maintenance, and all
details and variations of this equipment do not purport to be covered by these instructions. If further
information is desired by purchaser regarding this particular installation, operation or maintenance
of this equipment, the local ABB Power T&D Company Inc. representative should be contacted.
Printed in U.S.A.
 41-498B
Effective: August 1970
Supersedes I.L. 41-498A
Denotes Change Since Previous Issue
*
Type KS
Out-of-step Blocking Relay
0.51–30 Ohms
CAUTION
Before
putting
protective
relays
into
service
make
sure
that
all
moving
parts operate
freely
,
inspect
the
contacts
to
see
that
they
are
clean
and
close
properly
,
and
operate
the
relay
to
check the
settings
and
electrical
connections
.
APPLICATION
The
KD
-
3
relay
(
Figure
l
)
is
a
single
phase
impedance
type
relay
connected
to
receive
phase
-
to
-
neutral
voltage
and
phase
current
and
may
be
applied
as
a
supplement
to
conventional
two
-
zone
or
three
-
zone
distance
relaying
.
It
has
provisions
for
a
completely
offset
circle
characteristic
with
both the
long
reach
and
the
short
reach
adjustable
.
In KD
relay
applications
where
a
normal
second
zone
or
third
zone
setting
of
the
three
-
phase
unit
might
cause
tripping
because
of
possible
load
conditions
,
the
conventional
relay
settings
must
be
shortened
to
exclude load
.
The
KD
-
3
displaced
circle
characteris
-
tic
may
be
added
to
the
KD
relay
three
-
phase
unit
shortened
circle
characteristic
to
provide
the
desired
total
reach
at
the
line
angle
without
danger
of
tripping
on
load
.
The
KD
phase
-
to
-
phase
unit
does
not
respond
to
balanced
three
phase
conditions
and
therefore
can
be
set
for
any
distance
without
fear
of
tripping
on
load
or
swing
conditions
.
The
KD
-
3
relay
is
available with
either
a
1
ampere
or
a
0.2
/
2.0
ampere
indicating
contactor
switch
rating
.
The
1
ampere
rating
is
recommended
for
all
directional
comparison
applications
and
for
most
distance
relaying applications
.
The
0.2
/
2.0
ampere
rating
is
recommended for
distance
relaying
where
a
lockout
relay
is
ener
-
gized
or
where
a
high
impedance
auxiliary
tripping
relay
is
utilized
.
CONSTRUCTION
The
type
KD
-
3
relay
consists
of
two
single
air
gap
transformers
(
compensators
)
,
two
tapped
auto
-
transformers
,
a
cylinder
type
operating
unit
,
an
adjustable
reactor
and
an
ICS
indicating
contactor
switch
.
Courtesy of NationalSwitchgear.com

41-498B Type KD-3 Relay
2
Compensator
Compensators
,
which
are
designated
as
TA
and
TQ
,
are
two
-
winding
air
-
gap
transformers
(
Figure
2
)
.
The
primary
,
or
current
winding
,
has
seven
taps
which
terminate
at
the
tap
block
(
Figure
3
)
.
TA
is
the
''
long
reach
"
compensator
,
T
-
R
is
the
"
short
reach
"
compensator
and
tap
markings
for
the
respective
units
are
as
follows
:
TA
=
1.3
,
1.7
^
,
2.4
,
3.3
,
4.5
,
6.3
,
and
8.7
.
TB
=
.
87
,
1.16
,
1.6
,
2.2
,
3.0
,
4.2
,
and
5.8
.
Current
flowing
through
the
primary
coil
provides
an
f
>
lMF
which
produces
magnetic
lines
of
flux
in
the
core
.
A
voltage
is
induced
in
the
secondary
which
is
proportional
to
the
primary
tap
and
current
magnitude
.
This
proportionality
is
established
by
the
cross
sectional
area
of
the
laminated
steel
core
,
the
length
of
an
air
gap
which
is
located
in
the
center
of
the
coil
,
and
the
tightness
of
the
laminations
.
All
of
these
factors
which
influence
the
secondary
voltage
proportionality
have
been
precisely
set
at
the
factory
.
The
clamps
which
hold
the
laminations
should
not
be
disturbed
by
either
tightening
or
loosening
the
clamp
screws
.
The
secondary
winding
has
a
single
tap
which
divides
the
winding
into
two
sections
.
One
section
is
connected
subtractively
in
series
with
the
relay
terminal
voltage
.
Thus
a
voltage
which
is
proportional
to
the
line
current
is
subtracted
vectorially
from
the
relay
terminal
voltage
.
The
second
section
is
connected
to
an
adjustable
loading
resistor
and
provides
a
means
of
adjusting
the
phase
angle
relation
between
primary
current
and
the
induced
secondary
voltage
.
The
phase
angle
may
be
set
for
any
value
between
60
°
and
80
°
by
adjusting
the
resistor
between
its
minimum
and
maximum
values
respectively
or
for
89
°
torque
angle
of
75
°
current
lagging
voltage
.
Auto
-
Transformer
The
auto
-
transformer
has
three
taps
on
its
main
winding
,
S
,
which
are
numbered
1
,
2
,
and
3
on
the
tap
block
.
A
tertiary
winding
M
has
four
taps
which
may
be
connected
additively
,
or
subtractively
to
inversely
modify
the
S
setting
by
any
value
from
-
15
to
+
15
per
cent
in
steps
of
3
per
cent
.
The
sign
of
M
is
negative
when
the
R
lead
is
above
the
L
lead
.
M
is
positive
when
L
is
in
a
tap
location
which
is
above
the
tap
location
of
the
R
lead
.
The
M
settings
is
determined
by
the
sum
of
per
unit
values
between
the
R
and
L
lead
.
The
actual
per
unit
values
which
appear
on
the
tap
plate
between
taps
are
0
,
.
03
,
.
06
,
and
.
06
.
The
auto
-
transformer
makes
it
possible
to
expand
the
basic
range
of
the
compensators
by
a
multiplier
of
S
Therefore
,
any
relay
1
±
M
ohm
setting
can
be
made
within
dr
1.5
per
cent
from
1.13
ohms
to
30
ohms
,
for
a
long
reach
setting
,
and
from
0.75
ohms
to
20
ohms
,
for
a
short
reach
setting
,
by
combining
the
compensator
taps
T
^
Courtesy of NationalSwitchgear.com

Type KD-3 Relay 41-498B
3
and
Tc
with
the
auto
-
transformer
taps
and
M
^
,
and
SQ
and
MQ
.
Tripping
Unit
The
device
which
acts
to
initiate
tripping
is
a
four
-
pole
cylinder
unit
which
is
connected
so
that
one
pole
-
pair
voltage
leads
the
other
by
90
°
and
operates
as
a
two
-
phase
induction
motor
.
Contact
-
closing
torque
is
produced
by
the
unit
when
the
voltage
applied
to
its
terminals
has
a
negative
-
phase
sequence
.
Closing
torque
for
the
relay
forces
the
moving
contact
to
the
left
hand
side
as
viewed
from
the
front
of
the
relay
.
Contact
-
opening
torque
is
produced
when
positive
-
phase
sequence
voltages
are
applied
.
Hence
,
the
cylinder
unit
has
restraint
or
operating
torque
as
determined
by
the
phase
sequence
of
the
voltages
applied
to
its
terminals
.
Mechanically
,
the
cylinder
unit
is
composed
of
four
basic
components
;
a
die
-
cast
aluminum
frame
,
an
electromagnet
,
a
moving
element
assembly
,
and
a
molded
bridge
.
The
frame
serves
as
the
mounting
structure
for
the
magnetic
core
.
The
magnetic
core
which
houses
the
lower
pin
bearing
is
secured
to
the
frame
by
a
spring
and
snap
ring
.
This
is
an
adjustable
core
which
has
a
.
025
inch
flat
on
one
side
and
is
held
in
its
adjusted
position
by
the
clamping
action
of
two
compressed
springs
.
The
bearing
can
be
replaced
,
if
necessary
without
having
to
remove
the
magnetic
core
from
the
frame
.
The
electromagnet
has
two
series
-
connected
coils
mounted
diametri
-
cally
opposite
one
another
,
to
excite
each
set
of
poles
,
and
two
locating
pins
.
The
locating
pins
are
used
to
accurately
position
the
lower
pin
bearing
,
which
is
mounted
on
the
frame
,
with
respect
to
the
upper
pin
bearing
,
which
is
threaded
into
the
bridge
.
The
electromagnet
is
secured
to
the
frame
by
four
mounting
screws
.
The
moving
element
assembly
consists
of
a
spiral
spring
,
contact
carrying
member
,
and
an
aluminum
cylinder
assembled
to
a
molded
hub
which
holds
the
shaft
.
The
hub
to
which
the
moving
contact
arm
is
clamped
has
a
wedge
-
and
-
cam
construction
,
to
provide
low
-
bounce
contact
action
.
A
casual
inspection
of
the
assembly
might
lead
one
to
think
that
the
contact
arm
bracket
does
not
clamp
on
the
hub
as
tightly
as
it
should
.
However
,
this
adjustment
is
accurately
made
at
the
factory
and
is
locked
in
place
with
a
lock
nut
and
should
not
be
changed
.
Optimum
contact
action
is
obtained
when
a
force
of
4
to
10
grams
pressure
applied
to
the
face
of
the
moving
contact
will
make
the
arm
slip
one
-
fourth
of
its
total
free
travel
.
Free
travel
is
the
angle
through
which
the
hub
will
slip
from
the
condition
of
reset
to
the
point
where
the
clamp
projection
begins
to
ride
up
on
the
wedge
.
The
free
travel
can
vary
between
15
°
to
20
°
.
The
shaft
has
removable
top
and
bottom
jewel
bearing
,
rides
between
the
bottom
pin
bearing
and
the
upper
pin
bearing
which
is
adjusted
to
.
025
inch
from
the
top
of
the
shaft
bearing
.
The
shaft
Courtesy of NationalSwitchgear.com

41-498B Type KD-3 Relay
4
The
cylinder
rotates
in
an
air
gap
formed
by
the
electromagnet
and
the
magnetic
core
.
The
bridge
is
secured
to
the
electromagnet
and
frame
by
two
mounting
screws
.
In
addition
to
holding
the
upper
pin
bearing
,
the
bridge
is
used
for
mounting
the
adjustable
stationary
contact
housing
.
This
stationary
contact
has
.
002
to
.
006
inch
follow
which
is
set
at
the
factory
by
means
of
the
adjusting
screw
.
After
the
adjustment
is
made
the
screw
is
sealed
in
position
with
a
material
which
flows
around
the
threads
and
then
solidifies
.
The
stationary
contact
housing
is
held
in
position
by
a
spring
type
clamp
.
The
spring
adjuster
is
located
on
the
underside
of
the
bridge
and
is
attached
to
the
moving
contact
arm
by
a
spiral
spring
.
The
spring
adjuster
is
also
held
in
place
by
a
spring
type
clamp
.
When
the
contacts
close
,
the
electrical
connection
is
made
through
the
stationary
contact
housing
clamp
,
to
the
moving
contact
,
through
the
spiral
spring
and
out
to
the
spring
adjuster
clamp
.
Indicating
Contactor
Switch
Unit
(
ICS
)
The
indicating
contactor
switch
is
a
small
d
-
c
operated
clapper
type
device
.
A
magnetic
armature
,
to
which
the
leaf
-
spring
mounted
contacts
are
attached
,
is
attracted
to
the
magnetic
core
upon
energization
of
the
switch
.
When
the
switch
closes
,
the
moving
contacts
bridge
two
stationary
contacts
,
completing
the
trip
circuit
.
Also
during
this
operation
two
fingers
on
the
armature
deflect
a
spring
located
on
the
front
of
the
switch
,
which
allows
the
operation
indicator
target
to
drop
.
The
target
is
reset
from
outside
of
the
case
by
a
push
rod
located
at
the
bottom
of
the
cover
.
The
front
spring
,
in
addition
to
holding
the
target
,
provides
restraint
for
the
armature
and
thus
controls
the
pickup
value
of
the
switch
.
OPERATION
Type
KD
-
3
relays
have
two
major
components
,
the
compensators
and
the
tripping
unit
.
In
the
internal
schematic
of
Fig
.
4
compensators
designated
T
/
\
and
TQ
are
shown
connected
so
as
to
modify
the
voltage
applied
to
the
long
-
reach
coils
(
Zpy
?
)
and
the
short
-
reach
coils
(
£
SR
)
respectively
.
Operation
of
the
KD
-
3
relay
can
be
explained
by
referring
to
Fig
.
5
.
In
this
figure
the
addition
of
voltage
vectors
,
at
various
fault
locations
,
results
in
a
set
of
vectors
indicating
predominantly
positive
sequence
voltages
for
restraining
the
tripping
unit
or
indicating
predorninantely
negative
sequence
voltages
for
closing
the
tripping
unit
.
In
Fig
.
5
the
short
reach
setting
(
Zq
)
is
about
one
third
of
the
long
reach
setting
(
Z
^
)
and
is
in
the
same
direction
.
This
produces
the
solid
line
offset
circle
characteristic
which
excludes
the
Courtesy of NationalSwitchgear.com

Type KD-3 Relay 41-498B
5
origin
when
plotted
on
an
R
-
X
diagram
.
Note
that
if
Zc
had
been
set
with
reverse
polarity
,
by
reversing
the
external
current
connec
-
tions
,
the broken
line
circle
characteristic
which
includes
the
origin
would
have resulted
.
Terms
and
symbols
used
in
the
diagrams
are
defined
as
follows
:
Output
voltage
from
the
autotransformers
which
receive
phase
to
neutral
voltage
.
VSM
Mutual
impedance setting
of the
long
reach
compensator
.
ZA
Mutual
impedance
setting
of
the
short
reach
compensator
.
ZC
phase
Current
.
I
Z
(
LR
)
tripping
unit
coil
voltage
.
Z
(
SR
)
tripping
unit
coil
voltage
.
Positive
Sequence
(
restraining
)
phase
rotation
.
Negative
Sequence
(
closing
)
phase
rotation
.
Consider
a
fault
at
location
"
A
"
which
is
beyond
the
long
reach
setting
.
For
the
sake
,
of
simplicity
,
assume
both
the
line
angle
and the
relay
maximum
torque
angle
to
be
90
°•
Compensator
Z
^
modifies
voltage
Vgp
.
]
by
adding
the
mutual
impedance
drop
IZ
^
which
leaves
voltage
XY
across
the
Z
(
LR
)
coils
.
Compensator
ZQ
modifies
its
voltage
Vgj
/
j
by
adding
IZQ
to
produce
Z
’
Y
.
This
voltage
is
then
advanced
90
°
,
by
the
phase
shifting
action
of
capacitor
Ccs
,
to
provide
voltage
ZY
across
the
Z
(
SR
)
coils
.
The
resulting diagram
has
an
X
-
Y
-
Z
(
positive
sequence
)
pnase
rotation
which
restrains
the
unit
for
this
fault
beyond
the
protected
zone
.
Using
the
same
method
of
analysis
for
a
fault
at
location
"
B
"
,
the
long
reach
setting
Z
^
,
it
is
shown
that
X
,
Y
,
and
Z
lie
in
a
straight
line
indicating
equal
positive
and
negative
sequence
voltages
which
provides
a
balance
point
.
Within
the
protected
zone
,
for
a
fault
a
*
t
location
"
C
"
,
the
XY
voltage
is
reversed
by
compensa
-
tor
action
and
negative
sequence
voltage
X
-
Z
-
Y
produces
closing
torque
in
the
tripping
unit
.
At
location
"
D
"
,
the
short
reach
setting
,
another
balance
point
is
encountered
as
positive
sequence
and
negative
sequence
voltages
become
equal
again
with
X
,
Y
,
and
Z
in
line
.
XY
ZY
X
-
Y
-
Z
X
-
Z
-
Y
A
fault
at
location
"
En
whi
«
h
is
between
the
relay
and the
protected
zone causes
both
XY
and
ZY
to
be
reversed
,
restraining
^
X
-
Y
-
Z
phase
rotation
.
the
relay
,
causes
a
current
reversal
in
both
compensators
and
a
modifying
voltage
is
produced
which
increases
the
restraining
voltage
VSM
to
a
large
value
with
X
-
Y
-
Z
phase
rotation
.
This
provides
a
A
fault
at
location
"
F
"
,
behind
Courtesy of NationalSwitchgear.com

41-498B Type KD-3 Relay
6
The
combination
of
series
resistor
RA
and
parallel
capacitor
C
^
p
shown
in
Figure
4
controls
transients
in
the
Z
(
LR
)
circuit
and
also
provides
a
small
amount
of
phase
shift
.
In
the
Z
(
gR
)
circuit
,
capacitor
Cgg
provides
memory
action
to
improve
the
operaring
characteristics
for
faults
near
the
relay
location
.
CQS
also
provides
the
major
phase
shifting
effect
which
makes
the
voltage
across
Z
(
SR
)
lead
the
voltage
across
Zfjj
;
)
by
90
°
when
only
voltage
is
applied
to
the
relay
.
The
most
efficient
phase
relation
between
pole
pairs
for
the
cylinder
type
tripping
unit
is
90
°
which
can
be
accurately
set
using
the
variable
X
adjustment
.
Reactor
X
is
a
small
adjustable
unit
which
is
used
to
compensate
for
variations
in
other
components
.
CHARACTERISTICS
The
KD
-
3
relay
is
designed
to
respond
primarily
to
three
phase
faults
.
Since
it
receives
phase
-
to
-
neutral
voltage
and
phase
current
,
it
responds
accurately
to
any
three
phase
condition
and
to
phase
-
to
-
ground
faults
on
one
particular
phase
.
It
has
a
limited
response
to
phase
-
to
-
phase
and
double
-
phase
-
to
-
ground
faults
.
Distance
Characteristic
A
characteristic
circle
is
established
by
setting
two
points
on
the
circle
,
diametrically
opposite
one
another
,
by
means
of
the
Long
Reach
and
the
Short
Reach
compensators
.
As
shown
in
Figure
6
,
the
Short
Reach
setting
,
ZgR
,
may
be
positive
or
negative
with
respect
to
ZgR
,
or
it
may
be
zero
depending
upon
the
current
circuit
connections
to
the
Short
Reach
compensator
TQ
.
The
external
schematic
Figure
7
shows
positive
polarity
current
connections
to
both
TA
and
TQ
.
Solid
line
characteristics
of
Figure
6
are
typical
for
a
positive
Z
,
SR
.
Memory
action
in
the
tripping
unit
circuitry
provides
the
light
-
line
dynamic
characteristic
when
normal
voltage
exists
at
the
relay
terminals
prior
to
the
fault
.
The
heavy
-
line
static
characteristic
dominates
for
load
and
swing
conditions
or
if
there
is
zero
voltage
at
the
relay
prior
to
the
fault
.
The
broken
-
line
characteristic
passing
through
the
origin
is
obtained
by
by
-
passing
the
current
terminals
of
the
Tc
compensator
to
make
Zg
^
equal
to
zero
.
origin
is
obtained
by
making
reverse
polarity
connections
to
current
terminals
of
the
TQ
compensator
.
The
dashed
-
line
characteristic
which
includes
the
The
relay
is
inherently
directional
when
ZSR
is
either
zero
or
is
of
positive
polarity
.
If
TQ
has
a
negative
polarity
connection
to
the
current
terminals
,
Zgp
is
reversed
with
respect
to
ZLR
and
the
circle
characteristic
then
includes
the
origin
and
loses
its
sense
of
direction
.
Sensitivity
Figure
8
is
an
impedance
curve
which
demonstrates
the
relay
sensitiv
-
ity
to
faults
at
the
balance
point
for
various
values
of
voltage
at
the
relay
terminals
.
Courtesy of NationalSwitchgear.com

Type KD-3 Relay 41-498B
Zero
voltage
sensitivity
for
characteristics
which
include
the
origin
is
graphically
illustrated
in
Figure
9
.
General
Characteristic
Impedance
settings
in
ohms
reach
can
be
made
for
any
value
from
1.13
ohms
to
30
ohms
for
ZLR
and
from
.
75
ohms
to
20
ohms
for
Zgp
in
steps
of
3
per
cent
.
The
maximum
torque
angle
,
which
is
set
for
75
degrees
at
the
factory
,
may
be
set
for
any
value
from
60
degrees
to
80
degrees
.
A
change
in
maximum
torque
angle
will
produce
a
slight
change
in
reach
for
any
given
setting
of
the
relay
.
Referring
to
Figure
2
note
that
the
compensator
secondary
voltage
output
V
,
is
largest
when
V
leads
the
primary
current
,
I
,
by
90
°
.
This
90
°
relationship
is
approached
,
if
the
compensator
loading
resistor
(
F
*
2
A
or
°
Pen
-
ci
-
rcuit
ed
.
The
effect
of
the
loading
resistor
,
when
connected
,
is
to
produce
an
internal
drop
in
the
compensator
,
which
is
out
-
of
-
phase
with
the
induced
voltage
,
V
,
is
phase
-
shifted
to
change
the
compensator
maximum
torque
angle
.
As
a
result
of
this
phase
shift
the
magnitude
of
V
is
reduced
,
as
shown
in
Figure
2
.
Tap
markings
in
Figure
3
are
based
upon
a
75
°
compensator
angle
setting
.
If
the
resistors
R
2
A
and
R
2
C
are
adjusted
for
some
other
maximum
torque
angle
the
nominal
reach
is
different
than
indicated
by
the
taps
.
The
reach
,
ZQ
,
varies
with
the
maximum
torque
angle
,
9
,
as
follows
:
TS
sin
9
ZQ
-
(
1
t
M
)
sin
75
°
TAP
PLATE
MARKINGS
TA
1.3
1.7
^
2.4
3.3
4.5
6.3
8.7
TC
.
87
1.16
1.6
2.2
3.0
4.2
5.8
SC
&
Sc
12
3
+
Values
between
taps
MA
&
Mc
.
03
.
06
.
06
TIME
CURVES
AND
BURDEN
DATA
Operating
Time
The
speed
of
operation
for
the
KD
-
3
relay
is
shown
by
the
time
curves
in
Figure
10
.
The
curves
indicate
the
time
in
milliseconds
required
for
the
relay
to
close
its
contacts
for
tripping
after
the
inception
Courtesy of NationalSwitchgear.com

41-498B Type KD-3 Relay
8
of
a
fault
at
any
point
on
a
line
within
the
relay
setting
.
Current
Circuit
Rating
in
Amperes
Tap
Setting
Continuous
1
Second
S
=
1
S
2
S
=
3
5.8
8.5 8.5
240
5.0
4.2
6.0
240
10
.
10
.
8.0
3.0
240
10
.
10
.
2.2
240
10
.
10
.
10
.
1.6
240
10
.
10
.
10
.
1.16
0.87
240
10
.
10
.
10
.
240
10
.
10
.
10
.
Burden
The
burden
which
the
relay
imposes
upon
potential
and
current
transformers
is
shown
by
Figure
11
.
Trip
Circuit
Constants
1
ampere
rating
:
0.2
/
2.0
ampere
rating
:
0.1
ohms
d
.
c
.
resistance
0.2
tap
—
6.5
ohms
2
tap
-
-
0.15
ohms
SETTING
CALCULATIONS
Relay
reach
is
set
on
the
tap
plate
shown
in
Fig
.
3
.
markings
are
:
The
tap
TA
1.3
1.74
2.4
3.3
4.5
6.3
8.7
TC
.
87
l
.
16
1.6
2.2
3.0
4.2
5.8
SA
and
Sc
1
2
3
MA
and
Mc
.
03
.
06
.
06
(
Values
between
taps
)
Maximum
torque
angle
is
set
for
75
°
(
current
lagging
voltage
)
in
the
factory
,
of
65
°
or
higher
.
torque
angle
,
by
adjusting
R
2
A
and
R
2
C
*
This
adjustment
need
not
be
disturbed
for
line
angles
For
line
angles
below
65
°
,
set
for
a
60
°
maximum
Courtesy of NationalSwitchgear.com

Type KD-3 Relay 41-498B
9
The
general
formula
for
setting
the
ohms
reach
of
the
relay
is
:
(
Sin
6
)
Z
—
—
(
Sin
75
°
)
The
terms
used
in
this
formula
are
defined
as
follows
:
RC
-
zpri
Z
©
Rv
ZQ
=
the
desired
ohmic
reach
of
the
relay
and
relates
equally
to
Long
Reach
(
ZQ
^
)
and
Short
Reach
(
Z
0
gR
)
.
=
the
tap
plate
setting
.
TS
Z
1
-
M
T
=
compensator
tap
value
.
S
=
Auto
-
transformer
primary
tap
value
.
©
=
Maximum
torque
angle
setting
of
the
relay
.
Sin
Q
=
1
.
)
(
For
a
factory
setting
of
75
°
then
Sin
75
°
M
=
Auto
-
transformer
secondary
tap
value
.
(
This
is
a
Per
Unit
value
and
is
determined
by
the
sum
of
the
values
between
the
"
L
"
and
the
"
R
"
leads
.
The
sign
is
positive
when
"
L
"
is
above
"
R
"
and
acts
to
Lower
the
Z
setting
.
The
sign
is
negative
when
"
R
"
is
above
"
L
"
and
acts
to
raise
the
Z
setting
)
.
Zpri
-
ohms
per
phase
of
the
line
section
to
be
protected
.
Rc
=
current
transformer
ratio
.
Rv
=
potential
transformer
ratio
.
The
following
procedure
should
be
followed
in
order
to
obtain
an
optimum
setting
of
the
relay
.
Relate
the
general
equation
to
Long
Reach
or
Short
Reach
by
sub
letters
"
A
"
and
"
C
"
respectively
.
Select
the
lowest
tap
S
which
gives
a
product
of
10.3
and
6.9
SQ
greater
than
Z
where
Z
=
ZQ
(
sin
75
°
)
(
sin
0
)
*
1
.
Z
Select
a
value
for
T
that
is
nearest
the
value
2
.
S
Determine
the
value
of
M
that
will
most
nearly
make
3
.
TS
If
the
sign
is
negative
,
then
the
M
taps
-
1
.
M
Z
are
connected
with
the
R
lead
above
the
L
lead
to
Raise
the
setting
.
Courtesy of NationalSwitchgear.com

41-498B Type KD-3 Relay
10
For
example
,
assume
the
desired
reach
,
ZQLR
of
the
relay
is
10.8
ohms
at
60
degrees
.
Then
Zjj
{
=
10.8
x
1.11
=
12
ohms
.
The
lowest
tap
S
for
10.3
SA
greater
than
12
is
S
=
2
.
Set
SA
in
tap
2
.
TA
nearest
to
1
.
—
—
=
6.0
is
6.3
ohms
.
Set
TA
in
tap
6.3
2
.
2
12.6
-
1
)
=
(
1.05
-
1
)
=
0.05
(
Use
M
=
.
06
)
3
.
M
=
(
12
Set
MA
for
+
.
06
6.3
x
2
4
.
=
11.9
Then
=
l
f
.
06
(
Sin
0
)
5
.
=
1.07
relay
ohms
at
a
maximum
torque
This
is
of
the
desired
ZGLR
~
ZLR
angle
setting
of
60
degrees
,
value
.
(
Sin
75
°
)
6
.
for
a
600
maximum
torque
angle
.
Set
Ft
2
A
7
.
Use
the
same
six
steps
described
above
to
calculate
settings
for
TQ
,
SQ
than
zero
.
and
by
-
pass
the
current
terminals
of
TQ
.
SETTING
THE
RELAY
,
and
MQ
when
ZQ
^
R
IF
ZOSRI
5
4
°
ke
zero
,
set
is
any
value
other
SQ
on
1
,
MQ
for
0.0
,
The
KD
-
3
relay
requires
settings
for
each
of
the
two
compensators
(
Ta
and
TQ
)
,
each
of
the
two
auto
-
transformer
primaries
(
SA
and
SQ
)
,
and
for
the
two
auto
-
transformer
secondaries
(
MA
and
Me
)
.
All
of
these
settings
are
made
with
taps
on
the
tap
plate
which
is
located
above
the
operating
unit
.
Figure
3
shows
the
tap
plate
.
Compensator
(
TA
and
TQ
)
Each
set
of
compensator
taps
terminate
in
inserts
which
are
grouped
on
a
socket
and
form
approximately
three
quarters
of
a
circle
around
a
center
insert
which
is
the
common
connection
for
all
of
the
taps
.
Electrical
connections
between
common
insert
and
tap
inserts
are
made
with
a
link
that
is
held
in
place
with
two
connector
screws
,
one
in
the
common
and
one
in
the
tap
A
compensator
tap
setting
is
made
by
loosening
the
connector
screw
in
the
center
.
Remove
the
connector
screw
in
the
tap
end
of
the
link
,
swing
the
link
around
until
it
is
in
position
over
the
insert
for
the
desired
tap
setting
,
replace
the
connector
screw
to
bind
the
link
to
this
insert
,
and
retighten
the
connector
screw
in
the
center
.
Since
the
link
and
connector
screws
carry
operating
current
,
be
sure
that
the
screws
are
turned
to
bind
snugly
.
Courtesy of NationalSwitchgear.com