ABB KD-10 Manual

CAUTION
!
Before putting protective relays into service,
make sure that all moving parts operate freely, in-
spect the contacts to see that they are clean and
operate the relay to check the settings and electri-
cal connections.
1. APPLICATIONS
The type KD-10 relay (Figure 1), is a polyphase com-
pensator type relay which provides a single zone of
phase protection for all three phases. It provides es-
sentially instantaneous tripping for phase-to-phase
faults, two-phase-to-ground faults, and three-phase
faults within the reach setting and sensitivity level of
the relay.
The type KD-11 relay (Figure 1), is similar to the
KD-10 relay except that the characteristic impedance
circle for the 3-phase unit includes the origin. This re-
lay is usually applied as a carrier start relay in direc-
tional comparison blocking schemes but it may also
be used for time delay tripping in non pilot distance re-
laying. Both KD-10 and KD-11 relays have indicating
contactor switches rated 0.2/2.0 amperes. The 2.0
ampere tap must be used for directional comparison
blocking (KA-4) applications. The 2.0 ampere target is
recommended for direct trip applications. The 0.2 am-
pere target is recommended where a 125 or 250 volt
lockout relay (WL) is energized and 2.0 ampere
where a 48 volt lockout relay is used.
Refer to I.L. 40-208 for a description of how the KD-10
relay is used in directional comparison blocking sys-
tems.
For time-distance applications the KD-10 and
KD-11 relays are used with the TD-4, TD-52 or
TD-5 dc transistorized timers. See Figure 19 and 24
for the external schematics for 3 zone protection,
using the TD-4 and TD-52 relays, respectively. For
further discussion see Section 9, External Connec-
tions.
Fault detectors are used to supervise the trip circuit
for those applications where line side potentials are
used or loss-of-potential supervision is desired.
Otherwise, undesired tripping may occur on line os-
cillations or loss-of-potential. The cylinder type
KC-2orKC-4relay(2-8amperes)isrecommended.
The plunger or other magnetic attraction type relays
(e.g., a three unit SC relay or a three unit ITH relay)
may be used if the fault detector contacts carry trip
coil current rather than auxiliary relay (e.g., auxiliary
trip unit, timer, etc.) current.
The SC or ITH relay may also be used if a slow
dropout contact (e.g., TX contact of TD-5 timer re-
lay) is available to be connected around the fault
detector contacts.
2. CONSTRUCTION
The type KD-10 and KD-11 relays consist of the fol-
lowing: three single air gap transformers (compen-
sators, Figure 2), three tapped auto-transformers,
two cylinder type operating units, and an ICS indi-
cating contactor switch.
2.1 Compensator
The compensator, which is designated T (Figure 3),
is a two-winding air gap transformer with one prima-
ry current winding. The compensators, which are
designated TAB and TBC, are three-winding air gap
41-490H
ABB Power T&D Company Inc.
Power Automation and Protection Division
Coral Springs, FL 33065
Type KD-10 and KD-11
Compensator
Distance Relay
Instruction Leaflet
Effective : March 1997
Supersedes 41-490G Dated December 1990
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 Asea
Brown Boveri representative should be contacted.
(|) Denotes Change Since Previous Issue
iliiw
1111
lr
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I.L. 41-490H
2
transformers with two primary current windings.
Each primary current winding has seven taps which
terminate at the tap block (Figure 3). They are
marked:
Current flowing through the primary coil provides an
MMF which produces magnetic lines of flux in the
core.
A voltage is induced in the secondary which is pro-
portional to the primary tap and current magnitude.
This proportionality is established by the cross sec-
tional 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 fac-
tors which influence the secondary voltage propor-
tionality have been precisely set at the factory. The
clamps which hold the laminations should not be dis-
turbed by either tightening or loosening the clamp
screws.
The secondary winding has a single tap which di-
vides the winding into two sections. One section is
connected subtractively in series with the relay ter-
minal voltage. Thus a voltage which is proportional
to the phase current is subtracted vectorially from
the relay terminal voltage. The second section is
connected to a potentiometer and a fixed loading re-
sistor and provides a means of adjusting the phase
angle relation between primary current and the in-
duced secondary voltage.
2.2 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 in-
versely modify the S setting by any value from -18 to
+18 percent in steps of 3 percent.
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
setting 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, .09 and .06.
The auto-transformer makes it possible to expand
the basic range of “T” ohms by a multiplier of .
Therefore, any relay ohm setting can be made within
1.5 percent from the desired value by combining the
compensator taps T, TAB, and TBC with the au-
to-transformer taps S and M, SAand MA, and SC
and MC. See Tables I, II, and III for compilation of
settings available.
2.3 Tripping Unit
The device which acts to initiate tripping is a
four-pole cylinder unit which is connected open delta
and operates as a three-phase induction motor.
Contact-closing torque is produced by the unit when
the voltage applied to its terminals has a nega-
tive-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 re-
straint or operating torque as determined by the
phase sequence of the voltages applied to its termi-
nals.
Mechanically, the cylinder unit is composed of three
basic components: a die-cast aluminum frame and
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 0.020 inch flat on one side and is held in its adjust-
ed position by the clamping action of two com-
pressed 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 diametrically opposite one another to ex-
cite each set of poles. Locating pins on the electro-
magnet 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
Relay /
Ohms Taps
0.2-4.5
0.75-21.2
1.27-36.6
0.23
0.87
1.5
0.307
1.16
2.0
0.383
1.45
2.5
0.537
2.03
3.51
0.690
2.9
5.0
0.920
4.06
7.02
1.23
5.8
10.0
S
1 M ±
---------------
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I.L. 41-490H
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bridge. The electromagnet is permanently secured
to the frame and cannot be separated from the
frame.
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 pro-
vide low-bounce contact action. A casual inspection
of the assembly might lead one to think that the con-
tact 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.
The shaft has removable top and bottom jewel bear-
ings. The shaft 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 cylinder
rotates in an air gap formed by the electromagnet
and the magnetic core.
The bridge is secured to the electromagnet and the
frame by two mounting screws. In addition to holding
the upper pin bearing, the bridge is used for mount-
ing the adjustable stationary contact housing. This
stationary contact has .0015 to .0035 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 con-
tact housing is held in position by a spring type
clamp. The spring adjuster is located on the under-
side of the bridge and is attached to the moving con-
tact arm by a spiral spring. The spring adjuster is
also held in place by a spring type clamp.
The main contact of KD-10 and KD-11 relays will
close 30 amp at 250 Vdc and the seal-in contact of
the indicating contactor switch will carry this current
long enough to trip a breaker.
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.
2.4 Indicating Contactor Switch Unit (ICS)
The indicating contactor switch is a small dc operat-
ed clapper type device. A magnetic armature, to
which leaf-spring mounted contacts are attached, is
attracted to the magnetic core upon energization of
the switch. When the switch closes, the moving con-
tacts 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 tar-
get to drop. The target is reset from outside of the
case by a push rod located at the bottom of the cov-
er.
The front spring, in addition to holding the target,
provides restraint for the armature and thus controls
the pickup value of the switch.
3. OPERATION
The KD-10 relay has two major components: com-
pensators and tripping units. In the internal schemat-
ic of Figure 4 the compensators are designated T,
TAB and TBC, the tripping units, Z (3φ) and Z (φφ).
The phase-to-phase unit, Z (φφ) operates for all
combinations of phase to phase faults (phase A-B,
B-C, and C-A). The 3-phase unit Z (3φ) operates for
3-phase faults and for close-in-two-phase-to-ground
faults, although most two-phase-to-ground faults are
cleared by operation of the phase-to-phase unit.
Each of the tripping units and its associated com-
pensator circuit are electrically separate, and will
now be considered successively.
3.1 Three-Phase Unit
A single compensator T has its primary energized
with (IA-3I0) current; 3I0is the residual current. (See
External Schematic, Figure 19.) There are three
compensators shown one for each of the three
zones. One connection uses an auxiliary 5:5 ratio
current transformer to insert the -310component.
The alternate connection supplies the compensator
primaries with (-IB-IC). Since IA+IB+IC= 3I0, (IA-3I0)
= (-IB-IC). Current IA, IBand ICare the phase cur-
rents. The 3I0current is needed to provide overlap
with the φφ unit on 2-phase-to-ground faults.
Accordingly, the alternate connection is equivalent
to the first arrangement. Note that relay 21-3, a type
KD-11, also has a current winding Z. This winding is
wound on the tripping unit so that the R-X diagram
circle includes the origin, as explained under Section
4, Characteristics.
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I.L. 41-490H
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As shown in Figure 19, the T compensator second-
ary is connected to modify the phase A voltage. With
a fault in the trip direction, the induced voltage in the
compensator secondary bucks the phase A voltage.
Vector diagrams in Figure 8 illustrate the operation
during 3-phase faults at four locations. The system
impedance and the compensator angle are as-
sumedtobeat90°forillustrativepurposesonly.Pre-
fault voltages are depicted by the large dashed trian-
gle. The smaller dashed triangle in each case is the
system voltages at the relay location during the fault.
This triangle is modified by the compensator voltage
-1.5IAT where 1.5T is the compensator mutual im-
pedance. The terminals of the tripping unit are des-
ignated: X, Y and Z. Phase A tripping unit voltage is:
VX= 1.5 VAN-1.5 IAT (1)
Note that 3I0= 0 for 3-phase faults (2)
Phase B and phase C tripping unit voltages are:
VY=VBN (3)
VZ=VCN (4)
For a fault at A, beyond the relay operating zone, the
compensator voltage, -1.5IAT modifies the phase A
voltage, reducing the voltage triangle of the tripping
unit to X-Y-Z. With an X-Y-Z rotation the tripping unit
torque is in the restraining direction.
For a fault at B the current is larger than for a fault at
A, so that -1.5IAT is larger. The point X is in line with
points Y and Z. No torque is produced, since the
X-Y-Z triangle has a zero area.
For a fault in the operating zone, such as at C, point
X is below the YZ line. Now the rotation is X, Z, Y,
which produces operating torque.
For a fault behind the relay at D, restraining torque is
produced. Since the fault is behind the relay the cur-
rent is of reversed polarity. Compensator voltage,
-1.5AT, increases the area of the bus voltage trian-
gle, A-B-C. Tripping unit voltage has an X-Y-Z rota-
tion which produces restraining torque.
A solid 3-phase fault at the relay location, tends to
completely collapse the A-B-C voltage triangle. The
area of the X-Y-Z triangle also tends to be zero un-
der these conditions. A memory circuit in the KD-10
relay provides momentary operating torque under
these conditions, for an internal fault. In the KD-11
relay the winding Z in the current circuit, in conjunc-
tion with the compensator voltage, produces a cur-
rent-only torque, which maintains operating torque
under the condition of zero potential. In the short
reach relay the offset is obtained by means of an ad-
ditional compensator TBR.
The P3A - R3F parallel resistor-capacitor combina-
tion in the compensated phase provides correct
phase-angle relation between the voltage across the
front and back coils of Z (3φ) and the current, similar
phase shift is produced in left and right hand coils by
capacitor C3C. The P3A-C3A combination also pro-
vides control of transients in the coils of the cylinder
unit.
3.2 Phase-to-Phase Unit
Compensator primaries of TAB and TBC are ener-
gized by IA, IBand ICas shown in Figure 19. Com-
pensator secondaries are connected to modify their
respective phase voltages (e.g., TAB modifies VAB).
With a fault in the trip direction, the induced voltages
in the compensator secondaries buck the
phase-phase voltages.
Vector diagrams in Figure 9 illustrate the operation
during phase B-C faults at four locations. The sys-
tem impedances and the compensator angle are as-
sumed to be at 90°, for illustrative purposes. Prefault
voltages are depicted by the large dashed triangles.
The smaller light triangle in each case is the system
voltages at the relay location during the fault. This tri-
angle is modified by the compensator voltages
-(IA-IB)Z
C
and -(IC-IB) ZC. ZCis the compensator mu-
tual impedance. In this case IA= O. The terminals of
the tripping unit are designated; X, Y, and Z. Tripping
unit voltages for phase B-C faults are:
VXY = VAB -(IA-IB)ZC(5)
VZY = VCB -(IC-IB)ZC(6)
For a fault at A, in Figure 9 beyond the relay operat-
ing zone, the compensator voltages change the
A-B-C voltage sequence to the X-Y-Z sequence.
Voltages of this sequence applied to operating unit
produce restraining torque.
For a fault at B, the currents are larger than for a fault
at A, so that compensator voltages are larger. Points
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I.L. 41-490H
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Y and Z coincide now and the area of the X-Y-Z tri-
angle is zero. No torque is produced.
For a fault in the operating zone, such as at C, the
compensator voltages reverse the rotation of trip-
ping unit voltages to X-Z-Y sequence. Voltages of
this sequence applied to operating unit produce op-
erating torque.
For a fault behind the relay at D, restraining torque is
produced. Since the fault is behind the relay, the cur-
rent is of reverse polarity and tripping unit voltage
has an X-Y-Z rotation. This rotation produces re-
straining torque.
Note that this unit does not require memory action,
since the sound-phase voltage reacts with the com-
pensator voltage to produce a strong restraining or a
strong operating torque, depending upon the fault lo-
cation. This is true even for a complete collapse of
the faulted phase-to-phase voltage. The
phase-to-phase unit is identical in the KD-10 and
KD-11 relays.
Similar vector diagrams apply for a fault between
phases A and B or between phases C and A. Each
of the three phase-to-phase fault combinations sub-
jects the cylinder unit to a similar set of conditions.
4. CHARACTERISTICS
4.1 Distance Characteristics
Phase-to Phase Unit
This unit responds to all phase-to-phase faults and
most two-phase-to-ground faults. It does not re-
spond to load current, synchronizing surges, or
out-of-step conditions. While a characteristic circle
can be plotted for this unit on the R-X diagram, as
shown in Figure 10, such a characteristic circle has
no significance except in the first quadrant where re-
sistance and reactance values are positive. A small
portion of the fourth quadrant, involving positive re-
sistance values and negative reactance values,
could have some significance in the event that the
transmission line includes a series capacitor. The
portion of the circle in the first quadrant is of interest
because it describes what the relay will do when arc
resistance is involved in the fault. The
phase-to-phase unit operating on an actual trans-
mission system is inherently directional and no sep-
arate directional unit is required.
An inspection of Figure 10 indicates that the circle of
the phase-to-phase unit is dependent on source im-
pedance ZS. However the circle always goes
through the line balance-point impedance. The
reach at the compensator (and line) angle is con-
stant, regardless of the system source impedance.
The broadening out of the characteristic circle with a
relatively high source impedance gives the
phase-to-phase unit the advantageous characteris-
tic hat for short lines, it makes a greater allowance
for resistance in the fault. Stated another way, the
characteristics approach that of a reactance relay
more and more closely as the line being protected
becomes shorter and shorter with respect to the
source impedance back of the relaying location.
4.2 Sensitivity: Phase-to-Phase Unit
A plot of relay reach, in percent of tap block setting,
versus relay terminal voltage and current sensitivity
is shown in Figure 12. The unit will operate with the
correct directional sense for zero voltage
phase-to-phase faults. For this condition the fault
current must be not less than 0.015 relay amperes
with an ohm setting of 5.8 with rated voltage on the
unfaulted phase. Pick up current is proportionately
higher in S=2 and S=3 taps.
The KD-10 relay may be set without regard to possi-
ble overreach due to dc transients. Compensators
basically are insensitive to dc transients which at-
tend faults on high angle systems. The long time
constant of a high angle system provides a minimum
rate of change in flux-producing transient current
with respect to time, and therefore induces a mini-
mum of unidirectional voltage in the secondary.
Asymmetrical currents resulting from faults on
low-angle systems having a short time constant can
induce considerable voltage in the secondary, but
for the first half cycle, the transient-derived voltage
subtracts from the steady-state value. This transient
decays so rapidly that it is insignificant during the
second half cycle when it adds to the steady-state
value.
4.3 Distance Characteristic–
KD-10, 3-Phase Unit
The three-phase unit has a characteristic circle
which passes through the origin as shown in Figure
11. This circle is independent of source impedance.
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I.L. 41-490H
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The three-phase unit is also inherently directional
and does not require a separate directional unit.
Ifa solid three-phase fault occurs right at the relay lo-
cation, the entire voltage triangle collapses to zero a
balance point condition, as shown by the relay char-
acteristic in Figure 11 which passes through the ori-
gin. However, since the YZ voltage also drops to ze-
ro, the relay would be unable to determine whether
an internal or external fault existed. To correct this
condition, a resonant circuit is added to the C-B volt-
age circuit of the relay which allows the ZY voltage
to determine whether the fault is inside the protected
line section or behind the relay.
4.4 Sensitivity: KD-10, 3-Phase-Unit
The unit will operate with the correct directional
sense for zero voltage three-phase faults when nor-
mal voltage exists at the relay terminals prior to the
fault. This operation occurs due to memory action as
described above. The unit will have zero torque or
perhaps a slight opening torque if there is zero volt-
age at the relay prior to the fault or after the memory
action has subsided. For medium and long reach re-
lays with an impedance setting of 5.8 ohms the
three-phase unit will directionally operate for faults
which produce 2 volts line-to-line and 1.0 ampere at
the relay terminals.
Sensitivity with 2 volts line-to-line for any tap is de-
fined by Equation 7:
(7)
For short reach relays (0.2-4.5 ohms) with an imped-
ance setting of 1.23 ohms the three-phase unit will
directionally operate for faults which produce 0.5
volts line-to-line and 2.7 ampere at the relay termi-
nals.
Sensitivity with 0.75 volts line-to-line for any tap is
defined by Equation 8:
(8)
The KD-10 relay may be set without regard to possi-
ble overreach due to dc transients.
4.5 Distance Characteristic:
KD-11, 3-Phase Unit
The three-phase unit of the KD-11 relay has a char-
acteristic circle which includes the origin as shown in
Figure 13.
A single turn current coil on the cylinder unit provides
for current-only torque and is small compared to the
many turns of the T Max. setting of the compensator
and has very little influence on the overall settings.
However, as the compensator setting is reduced, the
single turn current coil becomes larger by compari-
son and has more and more effect on the overall set-
tings.
For 1.3–36.7 ohms range the reach and maximum
torque angle will vary approximately as follows:
For .75–21.2 ohms range the reach will vary approx-
imately as follows:
NOTE: When setting KD-11 Relays disregard
the change in T-Value, but
include the percentage error into test
current values.
The .2–4.5 ohms range KD-11 relays have no over-
reach regardless of the tap being used. The maxi-
mum torque angle will stay constant at 60°. The
I5.8
T
-------- amperes=
I3.4
T
-------- amperes=
T Nominal T Actual %
Overreach MTA Equiv. Reverse T
10
7.02
5.0
3.51
2.50
2.00
1.50
10.1
7.13
5.12
3.64
2.64
2.14
1.656
1.0
1.5
2.4
3.7
5.6
7.2
10.4
75
76
79
82
83
85
87
.13
.13
.12
.12
.11
.11
.11
T Nominal T Actual %
Overreach MTA Equiv. Reverse T
5.8
4.06
2.90
2.03
1.45
1.16
.87
5.92
4.18
3.036
2.17
1.615
1.33
1.05
2.2
3.4
7.6
5.9
8.3
12
17
79
80
82
85
89
91
98
.13
.13
.12
.12
.12
.11
.11
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I.L. 41-490H
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relay offset is nominal 0.1 ohms and its obtained by
a compensator TBR. Current-only torque is obtained
through the energy provided by the TBR compensa-
tor.
4.6 Sensitivity: KD-11, 3-Phase Unit
The impedance curve for the KD-11 three-phase unit
is shown in Figure 12.
The three-phase unit will operate to close the left
hand contact on current-only for the following condi-
tions:
For the .2–4.5 ohm range unit, the current sensitivity
is defined as the product of the current and the T set-
ting which must be equal to or greater than 6, i.e, (I
xT≥6).
4.7 General Characteristics
The phase-to-phase potential rating is 120 Vac
±10%.
Impedance settings in ohms reach can be made for
any value in the range of:
0.2 - 4.5 for short reach relays
0.75 - 21.2 for medium reach relays
1.27 - 36.6 for long reach relays.
The maximum torque angle for all phase-to-phase
units is set for 75 degrees at the factory, and may be
set for any value from 60 to 78 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 ap-
proached, if the compensator loading resistor (R2A,
or R2C) is open circuited. 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, ITAB or ITAC. Thus the net volt-
age, 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. Other angles may be set by changing re-
sistor R2A and R2C (or P2A and P2C).
Themaximumtorque angle of the 3-phase unit of the
medium (.73 - 21.2 ohms) and the long reach (1.27 -
36.6 ohms) is set for 75 degrees at the factory, and
it may be set for any value from 60 to 78 degrees.
Other angles may set by changing resistor R3.
Themaximumtorque angle of the 3-phase unit of the
short reach (.2 - 4.5 ohms) relay is set for 60 degrees
at the factory and may be set for any value from 45
to 63 degrees. By changing R3(or P3) any other an-
gle may be set. The 90-degree setting is approached
for all ranges when R3resistor is open circuited for
the 3φunit or R2A and R2C for the phase-to-phase
unit.
Tap markings are based upon nominal settings as
specified above. If the phase loading potentiometers
P3, P2A, or P2C are adjusted for some other maxi-
mum torque angle, the relay reach is different from
the nominal as described under settings.
5. Time Curves and Burden Data
5.1 Operating Time
The speed of operation for the KD-10 relay
three-phase and phase-to-phase units is shown by
the time curves in Figure 14. The curves indicate the
time in milliseconds required for the relay to close its
contacts for tripping after the inception of a fault at
any point on a line within the relay setting.
Figure 15 and Figure 16 show the KD-11 operating
time of the phase-to-phase unit and the three-phase
unit respectively. These curves show both con-
tact-opening time and contact-closing time for faults
within the relay setting.
5.2 Current Circuit Rating in Amperes
All current circuits are rated 10 amp continuous and
1 second rating is 240 amp except for 1-37 ohm
range where
for S = 1, T = 10, continuous rating is 6 amp
S = 2, T = 10, continuous rating is 8 amp
S = 3, T = 10, continuous rating is 9 amp
S = 1, T = 7.02, continuous rating is 7 amp
Range
(Ohms) T Set
Minimum
Amps
Required
.75-21.2
--
1.3-3.6
5.8
.87
10.0
3A
7.5A
3A
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I.L. 41-490H
8
5.3 Burden
The burden which the relays impose upon potential
and current transformers in each phase is shown by
Figure 17 and Figure 18 for the KD-10 and KD-11 re-
lays respectively. The potential burden and burden
phase angle are based on 69 volts line-to-neutral ap-
plied to the relay terminals.
5.4 Trip Circuit Constant
0.2 tap = 6.5 ohms
2 tap = 0.15 ohms
6. SETTING CALCULATIONS
Relay reach is set on the tap plate shown in Figure
3. The tap markings are:
Calculations for setting the KD-10 and KD-11 relays
are straightforward and apply familiar principles. As-
sume a desired balance point which is 90 percent of
the total length of line. The general formula for set-
ting the ohms reach of the relay is:
(9)
The terms used in this formula and hereafter are de-
fined as follows:
Z = The desired ohmic reach of the relay in
secondary ohms.
0.9 = The portion of the total line for which
the relay is set.
RC= Current transformer ratio
RV= Voltage transformer ratio
Zpri = Ohms per phase of the total line
section
The relay tap plate setting, Z, is set according to the
following Equation:
(10)
T = Compensator tap setting.
S = Auto-transformer primary tap setting.
±M = Auto-transformer secondary tap setting.
(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 set-
ting. The sign is negative when “R” is above
“L” and acts to raise the Z setting.)
CAUTION
!
The tap plate values of Tables I, II, and III
are based on standard maximum torque
angle settings.
In general recalibration of the relay to a
torque angle other than the standard val-
ue is neither desirable nor required.
Where it is necessary, the phase loading
potentiometers P3, P2A, or P2C can be
adjusted for other maximum torque an-
gle. The relay reach then becomes differ-
ent from the nominal tap plate settings
and tap plate setting should be modified
as outline under Section 6.2, Maximum
Torque Angle Consideration.
6.1 Obtaining an Optimum Setting of the
Relay.
a. Establish Z, as per Equation (9).
b. Now refer to Table I, II, or III. These tables list op-
timum settings for the relay.
1) Locate a table value for relay reach nearest to
the desired value Z (it will always be within
1.5% or less off the desired value).
2) Read off the Table “S”, “T” and “M” settings.
The “M” column includes additional information
T, TA, TB, and TC
(Short reach) 0.23, 0.307, 0.383, 0.537, 0.690, 0.920, 1.23
(Med. reach) 0.87, 1.16, 1.45, 2.03, 2.9, 4.06, 5.8
(Long reach) 1.5, 2.0, 2.5, 3.51, 5.0, 7.02, 10.0
(Values between taps)
S, SA, and SC
1, 2, 3
M, MA, MC
.0, .03, .09, .06
Z0.9 Zpri Rc
RV
-------
=
ZST
1M±
--------------=
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I.L. 41-490H
9
for “L” and “R” leads setting for the specified
“M” value.
3) Recheck the S, T, & M settings by using Equa-
tion (10).
–————–—| Example1 |———–———
Step 1 ___________________________________
Assume the desired reach, Z is 7.8 ohms at 75°.
Step 2a __________________________________
In Table II we find nearest value to 7.8 ohms 7.88
that is percent of the desired
reach.
Step 2b __________________________________
From Table II read off:
S=2
T = 4.06
M = +.03
and “L” lead should be connected over “R” lead, with
“L” lead connected to “.03” tap and “R” lead to tap
“0”.
Step 2c __________________________________
Recheck Settings.
6.1.1 Checking Relay Settings Using
Reverse Procedures
Tables I, II, or III can be used to check relay settings
in the field using the following reverse procedures:
1. Read off the tap plate T, S, M settings.
2. Find corresponding Z value from appropriate ta-
bles.
6.2 Maximum Torque Angle
Considerations
For Medium and Long Reach Relays maximum
torque angle is set at the factory for 75 degrees cur-
rent lagging voltage.
100 7.88
7.8
-----------
×101=
ZST
1M±
-------------- 2 4.06×
1.03+
--------------------- 7.88== =
For Short Reach Relays the maximum torque angle
of the three-phase unit is set for 60 degrees and the
phase-to-phase unit for 75 degrees.
6.2.1 Guidelines to Achieve Optimum
Application of the Relay to the Lines to be
Protected.
a. For Zone 1 application of KD-10 relays no setting
or calibration correction should be made if the line
angle is 65 degrees or higher for the medium and
long range relays (50 degrees for the short range
relay).
b. For pilot trip or timed trip (Zone 2 or 3, or KD-11)
applications no setting or calibration correction is
required regardless of the difference between the
relay and line angle.
c. For line angles below 65°for long and medium
reach KD-10 relays the difference between the re-
lay and line angles can be accounted for without
recalibration of the relay by matching the relay im-
pedance setting to the desired impedance value
of the line. (The recalibration of the relay to the
lower angle may be undesirable because the load
that can be accommodated by the 3φunit is lower.
See Figure 11.) The phase-to-phase unit is not re-
sponsive to load flow.
The setting calculations are done as follows:
If Z-line is the desired reach of the relay, the Z (the
relay setting) is
(11)
Where m is the maximum torque angle of the relay
a = Line Angle
–————–—| Example2 |———–———
If the desired reach is 5 ohms at 60°, a KD-10 relay
having an MTA of 75°should be set for:
or referring to Table II relay should be set: S = 1, T =
5.8, M = +.12.
ZZ line
Θma–()cos
---------------------------------=
Z5
75°60°–()cos
---------------------------------------- 515°cos ------------------- 5.18 ohms===
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I.L. 41-490H
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6.2.2 For Short Range Relay
(.2 - 4.5 ohms)
Zone 1 application for line angles below 50, recali-
brate the phase-to-phase unit to maximum torque
angle of 60°and the 3-phase unit for 45 degrees.
Set Zone 1 and reach for 90% of the line (85% for
line angles of less than 50°). In this case, follow the
procedure below: Recalibrate the relay for the new
maximum torque angle and set relay reach Z to be:
(12)
where θm- original maximum torque angle of
the relay
θ- the new maximum torque angle af-
ter relay recalibration
Zline- desired reach
“T”- values should be modified by the
ratio (sinθ/sinθm) to obtain the ac-
tual value of T.
–————–—| Example3 |———–———
a. Original nominal relay maximum torque angle
(short range relay).
m = 75°for phase-to-phase unit
m = 60°for three-phase unit
b. The desired reach is 0.5 ohms at 45°
c. Calculate settings: (Use Equation 12)
For phase-to-phase unit, recalibrated for 60°
For 3-phase unit, recalibrated for 45°
Referring to Table I, use closest setting for
phase-to-phase unit:
TA, TB, TB, TC= .537
MA, MC= -.06
SA, SC= 1
For 3-phase unit closest setting:
T = .690
M = +.12
S = 1
NOTE: If for some reasons an exact correction
is required to match up the line imped-
ance ZLat an angle α, and the relay has
been recalibrated from nominal maxi-
mum torque to a new maximum torque
angle β≠α, then the relay setting Z
should be equal to:
(13)
–————–—| Example4 |———–———
Relay with original θm = 75°has been recalibrated
to = 60°and to be applied to 5 ohm-line with line an-
gle a = 50°.
The relay setting Z relay should be according to
Equation (13):
Z relay =
Or, referring to Table II, the relay actual setting
should be:
S = 1
T = 5.8
M = +.03
7. SETTING THE RELAY
CAUTION
!
Since the tap block screw for all “T” taps carries
operating current, be sure that the screws are
turned tight.
In order to avoid opening current transformer
circuits when changing taps under load, the re-
lay must be first removed from the case. Chassis
operating shorting switches on the case will
short the secondary of the current transformer.
The taps should then be changed with the relay
outside of the case and then reinserted into the
case.
ZZ line θmsin
θsin
--------------------------------=
Z0.5 75°sin
60°sin
-------------------------- 0.557 ohms==
Z
0.5 60°sin
45°sin
-------------------------- 0.612 ohms==
Z
Z Line θm sin
ββα–()cossin
----------------------------------------=
575°sin
60 60°50°–()cos•sin
------------------------------------------------------------- 5.65 ohms=
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I.L. 41-490H
11
The KD-10 and KD-11 relays require settings for
each of the three compensators (T, TAB, and TBC),
each of the auto-transformers primaries (S, SA, and
SC) and secondaries (M, MA, and MC). All of these
settings are made with the relay de-energized using
taps on the tap plate located between the operating
units. Figure 3 shows the tap plate.
7.1 Compensator (T, TAB and TBC)
Each set of compensator taps terminate in inserts
which are grouped on a socket and form approxi-
mately three quarters of a circle around a center in-
sert 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. There are two TBsettings to be
made since phase B current is passed through two
compensators. A compensator tap setting is made
by loosening the connector screw in the center. Re-
move the connector screw in the tap end of the link,
swing the link around until it is in position over 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. Be careful
not to overtighten these screws.
7.2 Auto-Transformer Primary (S, SA,
and SC)
Primary tap connections are made through a single
lead for each transformer. The lead comes out of the
tap plate through a small hole located just below or
above the taps and is held in place on the tap by a
connector screw (see Figure 3).
An “S” setting is made by removing the connector
screw, placing the connector in position over the in-
sert of the desired setting replacing and tightening
the connector screw. The connector should never
make electrical contact with more than one tap at a
time.
7.3 Auto-Transformer Secondary (M, MA, and
MC)
Secondary tap connections are made through two
leads identified as L and R for each transformer.
These leads come out of the tap plate each through
a small hole, one on each side of the vertical row of
“M” tap inserts. The lead connectors are held in
place on the proper tap by connector screws.
Values for which an “M” setting can be made are
from -.18 to +.18 in steps of .03. The value of a set-
ting is the sum of the numbers that are crossed when
going from the R lead position to the L lead position.
The sign of the “M” value is determined by which
lead is in the higher position on the tap plate. The
sign is positive (+) if the L lead is higher and negative
(-) if the R lead is higher.
An “M” setting may be made in the following manner.
Remove the connector screws so that the L and R
leads are free. Determine from the Tables I to III the
desired “M” value. Neither lead connector should
make electrical contact with more than one tap at a
time.
7.4 Line Angle Adjustment
Maximum torque angle adjustment, if required, is ac-
complished by adjusting the compensator loading
resistors P3, P2A, and P2C. Refer to Section 13, Re-
pair Calibration, for procedure.
7.5 Indicating Contactor Switch (ICS)
Connect the lead located in front of the tap block to
the desired setting by means of the connecting
screw. When the relay energizes a 125 or 250 volt dc
type WL relay switch, or equivalent, use the 0.2 am-
pere tap; for 48 volt dc applications set the unit in a
tap2anduseatypeWLrelaywithaS#304C209G01
coil, or equivalent. The relay is shipped set for 2.0
tap.
8. INSTALLATION
The relays should be mounted on switchboard pan-
els or the equivalent in a location free from dirt, mois-
ture, excessive vibration and heat. Mount the relay
vertically by means of the mounting stud for the type
FT projection case or by means of the four mounting
holes on the flange for the semi-flush type FT case.
Either the stud or the mounting screws may be uti-
lized for grounding the relay. The electrical connec-
tions may be made directly to the terminals by
means of screws for steel panel mounting or to the
terminal stud furnished with the relay for thick panel
mounting. The terminal stud may be easily removed
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I.L. 41-490H
12
or inserted by locking two nuts on the stud and then
turning the proper nut with a wrench.
For detail information on the FT case refer to I.L.
41-076. The relay contacts should stay open with
panel de-energized.
9. EXTERNAL CONNECTIONS
Figure 19 shows the connections for 3-zone protec-
tion utilizing the TD-4 timer. Figure 24 is similar to
Figure 19 except that the TD-52 timer is used in-
stead of the TD-4. Figure 20 and Figure 21 show the
use of a 15/5 auxiliary current transformer so that the
CT neutral may be formed elsewhere.
Ac connections for additional applications are shown
in Figures 20, 21, 22 and 23. Three of these, Figures
20, 21, and 22 apply when the transmission line is
terminated in a power transformer, and when low
side voltage and current are used to energize the re-
lays. In calculating the reach setting, the bank im-
pedance must be added to the line impedance.
For the case of a wye-delta bank (Figures 21 and 22)
the voltages and currents are phase-shifted by 30;
however, this fact should be ignored, as the KD-10
and KD-11 relays are not affected by this
phase-shift.
Figure 23 shows a KD-10 and TD-5 relay connected
for generator back-up protection.
10. SWITCHBOARD TESTING WITH
KD-10 AND KD-11 RELAYS
Immediately prior to placing the relay in service, the
external wiring can be checked by manipulating the
current and voltage applied to the relay. If such a
check is desired, refer to Appendix A for the proce-
dure.
10.1 Current Voltage Relays with Mutual
Reactor Precautions
Relays which include compensators to modify the
applied voltage (such as the KD types) will produce
an output at their voltage terminals when the current
circuits are energized.
Thus, it is possible to pull potential fuses and still
havevoltageappearon the relay side of the fuses.
The magnitude of this voltage is dependent on mag-
nitude of load or fault current, relay settings, relay
impedance, and other potential circuit burden con-
nected in parallel with the relay containing the com-
pensator.
To avoid any difficulties due to interaction between
current and voltage circuits, it is recommended that
when PT fuses have been pulled to permit work on
voltage circuits, that these circuits should not be
considered safe until the current circuits have been
de-energized, or until the voltage circuits have been
shorted on the relay side of the fuses.
11. ACCEPTANCE TESTS
KD-10 and KD-11 relays have a very small number
of moving parts which might become inoperative.
Acceptance tests in general consist of:
a. A visual inspection to make sure there are no
loose connections, broken resistors, or broken re-
sistor wires.
b. An electrical test to make certain that the relay
measures the balance point impedance accurate-
ly.
11.1 Electrical Tests
An adjustable source of three-phase voltage and an
adjustable single-phase current along with a means
for varying the phase relation between current and
voltage are required for testing the relay. The volt-
age source may be either “open delta”, “closed del-
ta”, or “wye” connected. However, the relay operates
only on delta quantities since it has no neutral con-
nection.
Check electrical response of the relay using test
connections shown in Figure 25. Figure 26 features
the same connections except shows the use of addi-
tional switches that facilitate fast switchover from
“phase-to-phase” fault mode to “three-phase” fault
mode. Test connections, referred to in the test pro-
cedures, are the same on both drawings. Accuracy
of the test results will depend to large degree on the
accuracy of the instrumentation used. In general, it is
advisable to restrict instrument readings to the last
20 percent of the scale. For most accurate phase an-
gle readings use phase-shifter scale. This method
requires calibration of the scale using accurate watt-
meter (at 90°–0 watts and at 0°–maximum watts), or
an accurate phase angle meter.
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I.L. 41-490H
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TABLE I
RELAY SETTINGS FOR KD-10 & KD-11 RELAYS (.2 - 4.5 OHMS)
S = 1 S = 2 S = 3 LEAD CONNECTION
∆
T.230 .307 .383 .537 .690 .920 1.23 .69 .920 1.23 .92 1.23 +M -M “L”
Lead “T” Lead
.195 .260 .325 .455 .585 .780 1.042 - 1.56 2.08 - 3.13 +.18 - .06 0
“L” OVER “R”
.200 .267 .333 .467 .600 .800 1.070 - 1.60 2.14 - 3.21 +.15 - .06 .03
.205 .274 .342 .479 .616 .821 1.098 - 1.64 2.20 - 3.29 +12 - .09 0
.211 .282 .351 .493 .633 .844 1.128 - 1.69 2.26 - 3.39 +.09 - .09 .03
.217 .290 .361 .507 .651 .868 1.160 - 1.74 2.32 - 3.48 +.06 - .06 .09
.223 .298 .372 .521 .670 .893 1.194 - 1.79 2.39 - 3.58 +.03 - .03 0
.230 .307 .383 .537 .690 .920 1.230 - 1.84 2.46 - 3.69 0 0 0 0
.237 .316 .395 .554 .711 .948 1.268 - 1.90 2.54 - 3.80 - -.03 0 .03
“R” OVER “L”
.245 - .407 .571 .734 .979 1.308 - 1.96 2.62 - 3.93 - -.06 .09 .06
.253 - .421 - .758 1.011 1.352 1.52 2.02 2.70 3.03 4.05 - -.09 .03 .09
- - .435 - - - 1.398 - 2.80 - 4.19 - -.12 0 .09
- - .451 - - - 1.447 - 2.89 - 4.34 - -.15 .03 .06
----- -1.50 - 3.00 - 4.5 - -.18 0 .06
∆The tap plate values refer to standard maximum torque angle adjustment which is 75°for phase-to-phase unit
and 60°for three phase unit.
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I.L. 41-490H
14
TABLE II
RELAY SETTINGS FOR KD-10 & KD-11 (0.75 - 21.2)
∆The tap plate values refer to standard maximum torque angle adjustment which is 75°for both units.
S = 1 S = 2 S = 3 “M” LEAD CONNECTION
∆
T .87 1.16 1.45 2.03 2.9 4.06 5.8 4.06 5.8 4.06 5.8 +M -M “L” Lead “R” Lead
.737 .98 1.23 1.72 2.46 3.44 4.92 - 9.83 - 14.7 +.18 - .06 0
“L” OVER “R”
.757 1.01 1.26 1.77 2.52 3.53 5.04 - 10.1 - 15.1 +.15 - .06 .03
.777 1.04 1.29 1.81 2.59 3.63 5.18 7.25 10.4 - 15.5 +.12 - .09 0
.798 1.06 1.33 1.86 2.66 3.72 5.32 7.45 10.6 - 16.0 +.09 - .09 .03
.821 1.09 1.37 1.91 2.74 3.83 5.47 7.66 10.9 - 16.4 +.06 - .06 .09
.845 1.13 1.41 1.97 2.82 3.94 5.63 7.88 11.3 - 16.9 +.03 - .03 0
.870 1.16 1.45 2.03 2.90 4.06 5.80 8.12 11.6 - 17.4 0 0 0 0
.897 1.20 1.49 2.09 2.99 4.19 5.98 8.37 12.0 - 17.9 - -.03 0 .03
“R” OVER “L”
.926 - 1.54 2.16 3.09 4.32 6.17 8.64 12.3 - 18.5 - -.06 .09 .06
.956 - 1.59 2.23 3.19 4.46 6.37 8.92 12.7 - 19.1 - -.09 .03 .09
- - 1.65 2.31 3.30 4.61 6.59 9.23 13.2 - 19.8 - -.12 0 .09
- - 1.71 2.39 3.41 4.78 6.82 9.55 13.6 14.3 20.5 - -.15 .03 .06
- - - - - - 7.07 - 14.14 - 21.2 - -.18 0 .06
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I.L. 41-490H
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TABLE III
RELAY SETTINGS FOR KD-10 & KD-11 RELAYS (1.3 - 36.6)
∆The tap plate values refer to standard maximum torque angle adjustment which is 75°for both units.
S = 1 S = 2 S = 3 “M” LEAD CONNECTION
∆
T1.5 2.0 2.5 3.51 5.0 7.02 10.0 7.02 10 7.02 10 +M -M
1.27 1.69 2.12 2.97 4.24 5.94 8.47 - 16.9 25.4 +.18 .06 0
“L” OVER “R”
1.30 1.74 2.17 3.05 4.35 6.10 8.70 - 17.4 26.1 +.15 .06 .03
1.34 1.79 2.23 3.13 4.46 6.27 8.93 12.5 17.9 26.8 +.12 .09 0
1.38 1.83 2.29 3.22 4.59 6.44 9.17 12.9 18.3 27.5 +.09 .09 .03
1.42 1.89 2.36 3.31 4.72 6.62 9.43 13.2 18.9 28.3 +.06 .06 .09
1.46 1.94 2.43 3.44 4.85 6.82 9.71 13.6 19.4 29.1 +.03 .03 0
1.50 2.0 2.50 3.51 5.00 7.02 10.0 14.0 20.0 30.0 0 0 0 0
1.55 2.06 2.58 3.62 5.15 7.24 10.3 14.5 20.6 30.9 - -.03 0 .03
“R” OVER “L”
1.60 - 2.66 3.73 5.32 7.47 10.6 14.9 21.3 31.9 -.06 .09 .06
1.65 - 2.75 3.86 5.49 7.71 11.0 15.4 22.0 33.0 -.09 .03 .09
- - 2.84 3.99 5.68 7.98 11.4 16.0 22.7 34.1 -.12 0 .09
- - 2.94 4.13 5.88 8.26 11.8 16.5 23.5 24.8 35.3 -.15 .03 .06
- - - - - - 12.2 24.4 36.6 -.18 0 .06
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I.L. 41-490H
16
Make sure that correct lead-lag reference is estab-
lished. Once the phase-shifter is calibrated, remove
the wattmeter from the circuit. Make all phase angle
reading from phase-shifter scale. This method elimi-
nates the need for switching the current ranges in
phase angle meter when used and results in superi-
or accuracy. Always observe contact condition be-
fore current is applied. Closed contacts indicate re-
verse voltage sequence applied. Special attention
should be paid to the phase-to-phase fault mode.
Testing may be done outside the case for conve-
nience. All Current Readings include ±6 percent
tolerance. This tolerance includes ±2.5 percent fac-
tory tolerance and ±3.5 percent allowance for total
instrumentation error.
All Phase Angle Settings are fault current lagging
the VPH1-PH2 voltage.
The impedance measured by the 3-phase unit in test
1 (Figure 26) is
(14)
where VL-L is the phase-to-phase voltage and ILis
the test current; similarly, in tests 5, 6 & 7 of Figure
26 the phase-to-phase unit measures.
(15)
With phase-shifter set at maximum torque angle
(θm).
(16)
(17)
When testing the 3-phase unit, phase-shifter set-
tings are always set for 30°higher than nominal
maximum torque angle to account for test set-up
where all angle measurements are made with refer-
ence to phase-to-phase and not phase-to-neutral
quantities. The three phase unit maximum torque
angle is always referenced to phase-to-neutral.
At any other angle α, relay reach is
(18)
where Zθ= relay reach at maximum torque angle
θm.
Test current Iαis calculated as
(19)
Iθm= test current at θm
Equation (19) should be used to predict test current
when plotting impedance circle response of the re-
lay.
The relay is set according to the following chart.
If the relay is tested with other settings than specified
in acceptance test use voltage levels specified here,
except double the voltage specified for S = 2 settings
and triple for S = 3 settings.
When testing KD-11 relays with other settings than
specified here, refer to correction factors listed under
Section 4.5, Distance Characteristic: KD-11,
3-PHASE Unit.
Use Equations (16) and (17) to estimate test current,
and allow ±5 percent tolerance as explained above.
11.2 Reverse Reach Check for KD-11
(.2 - 4.5 OHM Range Only)
Use voltage test connection #1 and set voltages
V1F2F = 50 volts V2F3F = 2 volts: connect current
lead “23” to “terminal 15, and current lead “22” to
lead marked “21”. Set phase-shifter for current to lag
V1F2F voltage by 30°this current connection is
equivalent to phase B current lagging VBN voltage
by 60°in the reverse directions. Adjust current for
ZR VLL–
1.73IL
-----------------=
ZR VLL–
2I
L
---------------=
Itest 3 phase()
V
LL–
1.73ZR
-------------------=
Itest ΘΘ–()
V
LL
2ZR
----------=
Relay Range .2-4.5 .75-21.2 1.3-36.5
T, TA, TB, TB, TC
M, MA, MC
S, SA, SC
Z ohms
1.23
+.15
1.0
1.07
5.8
+.15
1.0
5.04
10.0
+.15
1.0
8.7
ZZ
θθ m
α–()cos=
IαIθm
θmα–()cos
--------------------------------=
I
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I.L. 41-490H
17
3-phase unit to operate between 10.5 - 12.7 am-
peres.
Use Equations (16) and (17) to estimate test current,
and allow 5 percent tolerance as explained above.
11.3 Three-Phase Unit (Lower Unit)
A. Use test connections #1 of Figure 25 and set
V1F2F = V1F3F = 30 volts.
The current required to close contacts of the bottom
unit should be:
∆If maximum torque angle θmhas been changed to a new
angle, the new
(20)
then test relay at the new β– angle
11.4 Phase-to-Phase Unit (Top Unit)
a. Use test connection #5; set VF1F2 = 30 volts =
Vfault
Note that to set this voltage; set voltage
V1-1F = V2-2F, first.
Make sure that,
(21)
–————–—| Example5 |———–———
If Vin = 120
Vfault = 30
then
trimuponeofthesevoltagestosetVFAULT
at exact value.
The current required to close contacts of the top
unit should be:
∆If maximum torque angle, θm, has been changed to a
new angle, use Equation (20) for trip current limits.
b.Repeat the test using test connections #6 and #7
11.5 Maximum Torque Angle Test
If maximum torque angle test performance is desired
follow instructions under Section13, Calibration al-
lowing ±5˚tolerance. Observe the same voltage and
current limits correction as mentioned above when
relayisset for other settings than specified here. The
test currents should be modified by following multi-
plier:
or .2 - 4.5 ohm range
or .75 - 21.2 ohm range
for 1.3 - 36.6 ohm range
11.6 Indicating Contactor Switch (ICS)
Close the main relay contacts and pass sufficient dc
through the trip circuit to close the contacts of the
ICS. The current should not be greater than the par-
ticular ICS tap setting being used for the 0.2 - 2.0
ampere ICS. The operation target should drop free-
ly.
The contact gap should be approximately 0.047" be-
tween the bridging moving contact and the adjust-
able stationary contacts. The bridging moving con-
tact should touch both stationary contacts
simultaneously.
If the electrical response is outside the limits a more
complete series of tests outlined in the Section 13,
Repair Calibration may be performed to determine
which component is faulty or out of calibration.
Relay Range .2-4.5 .75-21.2 1.3-36.6
Trip Current Amp 15.3-17.6 3.3-3.38 1.90-2.16
∆Phase-Shifter
set at
Nominal Maximum
Torque Angle θm
90˚
60˚
105˚
75˚
105˚
75˚
It
Itθm sinβsin
--------------------=
V11F–V
22F–
V
in Vfault
–
2
-------------------------------==
V
11F–V 22F–120 30–
2
---------------------- 45 volts,== =
Range .2 - 4.5 .75 - 21.2 1.3 - 36.6
∆Trip Current
(It) amperes 13.3 - 14.7 2.85 - 3.15 1.63 - 1.80
Phase-Shifter
Set Current
Lagging V1F-2F 75˚ 75˚ 75˚
1.07
Z
-----------
5.03
Z
-----------
8.7
Z
--------
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I.L. 41-490H
18
12. ROUTINE MAINTENANCE
The relays should be inspected periodically, at such
time intervals as may be dictated by experience, to
insure that the relays have retained their calibration
and are in proper operating condition.
All contacts should be cleaned periodically. A con-
tact burnisher #182A836H01 is recommended for
this purpose. The use of abrasive material for clean-
ing contacts is not recommended because of the
danger of embedding small particles on the face of
the soft silver and thus impairing the contact.
See Appendix B for additional information.
12.1 Distances Units
CAUTION
!
Before making “hi-pot” tests, jumper all contacts
together to avoid destroying arc suppressor ca-
pacitors.
For effective and quick maintenance it is advisable
to repeat the acceptance test with the field settings.
Then use portable test equipment such as the
K-DAR test set (I.L. 41-493.1) to record K-DAR test
set dial readings. In the future all field tests can be
made with the K-DAR test box just by referring to the
previous dial readings without using more elaborate
test set up of Figure 26. When testing with S=2, dou-
ble the test voltage. When testing with S=3, triple the
test voltage. Note that KD-11 reach and maximum
torque angle are increased with the lower T-settings
(see Section 4.5, Distance Characteristics: KD-11,
3-Phase Unit).
12.2 Indicator Contactor Switch (ICS)
Close the main relay contacts and pass sufficient dc
current through the trip circuit to close the contacts
of the ICS. The current should not be greater than
the particular ICS tap setting being used for the
0.2-2.0 amperes ICS. The operation indicator target
should drop freely.
13. REPAIR CALIBRATION
See Appendix B for additional information and for
trouble shooting limits.
Use the following procedure for calibrating the relay
if the relay has been taken apart for repairs or the ad-
justments disturbed.
Connect the relay for testing as shown in Figure 25.
Figure 26 shows a four-pole-double-throw switch in
the test circuit that selects a phase-to-phase or a
three-phase fault voltage condition, that will be ap-
plied to the relay voltage terminals. The rotary switch
switches the fault voltage to various terminals and
thereby simulates any phase combination of the
phase-to-phase fault without the tester having to
change connections or readjust the phase-shifter
and variable auto-transformers.
For best results in checking calibration, the relay
should be allowed to warm up for approximately one
hour at rated voltage in a case. However, a cold re-
lay will check to within three percent of the warm re-
lay. The relay may be calibrated outside the case.
13.1 Initial Spring Setting
Set the moving contact spring adjuster so that the
contact floats freely in the gap. Make sure that there
is no friction which prevents free movement of the
cylinder and contact arm.
13.2 Shaft Clearance
The upper pin bearing should be screwed down until
there is approximately .025 inch (one complete turn
of the screw) between it and the top of the shaft
bearing. The upper pin bearing should then be se-
curely locked in position with the lock nut. The lower
bearing position is fixed and cannot be adjusted.
13.3 Auto-Transformer Check
Auto-transformers may be checked for turns ratio
polarity by using the No. 1 test connections of Figure
25, and the procedure outline below.
Set S, SA, and SCon tap number 3. Set the “R” leads
of M, MA, MCall on 0.0 and disconnected all the “L”
leads. Adjust the voltages V1F2F and V2F3F for 90
volts. Measure the voltage from terminal 8 to the #1
tap of S and SA. It should be 29.4 volts. From 8 to the
#2 tap of S and SA should be 58.6 volts. The voltage
shouldread29.4voltsfrom8toSC=1and58.6volts
from 8 to SC= 2.
Set S, SA, and SCon 1 and adjust V1F2F and V2F3F
for 100 volts. Measure the voltage drop from termi-
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I.L. 41-490H
19
nal 8 to each of the M and the MAtaps. This voltage
should be equal to 100 (1 + the sum of values be-
tween R and the tap being measured). Example
100(1+.03+.09) = 112 volts.
Check the taps of MCin the same manner. Trans-
former that have an output different from nominal by
more than 1.0 volts probably have been damaged
and should be replaced.
13.4 Distance Unit Calibration
a. Make the following relay settings:
b. Read Section 11.1, Electrical Tests and Section
12.1, Distance Unit Electrical Test, to become fa-
miliar with testing connections, instrumentation,
and measurements. Use Figure 25 or 26 for test
connections.
14. Three-Phase Unit (Lower Unit) P3,
Core, & P3A Adjustments.
Use test connections #1 and set V2F1F = V2F3F = 25
volts. The current required for test should be:
For others angles set test current according to Equa-
tion (12).
14.1 P3Adjustment
To check the P3adjustment, measure voltage
across C3A. Vary phase angle in both directions of
the set value, to see that a low voltage across C3A
(below 1 volt) is obtained at the maximum torque an-
gle setting. If minimum voltage is within 2 degrees,
do not readjust. If the minimum voltage is obtained
at some other angle readjust phase-shifting resistor
or potentiometer (P3) at the desired angle.
14.2 Core Adjustment
For an initial adjustment of the core, restraint spring
is to be set as above per Section 13.1, Initial Spring
Adjustment. The relay should be preheated for at
least one hour in the case with closed cover to com-
pensate for effects of self-heating.
a. Connect relay terminal 8 and 9 together, apply rat-
ed ac voltage between terminals 7 and 8. Adjust
core by turning it slightly until the contact arm
floats or restrains very slightly.
b. KD-10 ONLY: Connect the relay terminals 7 and
8 together and apply rated ac voltage between 7
and 9. Adjust core until the contact arm just floats
or restrains very slightly. If this is not possible, ro-
tate core 90°and adjust. Recheck part “1” to de-
termine if contact is floating or restraining. If not,
repeat parts 1 and 2.
14.3 P3A Adjustment
Remove current. Connect relay terminals 7 and 9 to-
gether and apply rated ac voltage between 7 and 8.
Adjust P3A so that the 3-ph unit contact just floats or
restrains very slightly. If P3A does not have sufficient
range to make this adjustment, use R3F resistor to
bring P3A within the necessary range.
This calibration point is temperature sensitive and
will change with time if capacitor C3C drifts. The re-
lay contacts must stay open when terminals 7 and 9
are shorted and rated voltage is applied between ter-
minals 7 and 8, with no current applied.
This test assures proper response of the
3-phase-unit for 3-phase faults and for CA
phase-to-phase faults.
14.4 Final Core Adjustment for
KD-10 ONLY.
This check is done to prevent contact closing on cur-
rent-only.
a. Short circuit relay terminals 7, 8 and 9 together.
b. Pass 5 amperes in the current circuit in terminal
18 out terminal 19 increase the current to 30 am-
peres in convenient steps.
c. Relay contacts should stay open. If contacts
close, turn core further 90 degrees and repeat
parts 1, 2 and 3 of Section 14.2, Core Adjustment.
Relay Range .2 - 4.5 .75 - 21.2 1.27 - 36.6
T, TA, TB, TB, TC
M, MA, MC
S, SA, SC
1.23
+.15
1.0
5.8
+.15
1.0
10.0
+.15
1.0
Relay Range .2 - 4.5 .75 - 21.2 1.3 - 36.6
Current 15.6 3.3 1.92
Phase-shifter Settings 60˚ 75˚ 75˚
The Nominal M-T-Angle 60˚ 75˚ 75˚
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I.L. 41-490H
20
d. The KD-11 relay is purposely biased to produce
current-only contact-closing torque and will open
its right hand contact at a current value of 3 am-
peres or less when T is on maximum tap.
(For .2-4.5 ohm range relay the current only oper-
ation will occur at IA= 5∠0˚amp and IB= 5∠120˚
if two phase currents are available.)
14.5 Maximum Torque Angle Check
a. Use test connection #1.
b. Adjust voltages V1F-2F and V2F-3F, and current
as per table below:
c. Check maximum torque angle using procedure
described below:
Rotate the phase-shifter to find the angles, θ1 and
θ2, at which the bottom unit contacts just close.
The maximum torque angle θmfor the
three-phase-unit then is degrees.
The 30 degree correction is made to account for the
fact that test set up angle measurements are made
with reference to phase-to-phase voltage instead of
line-to-neutral voltages. The 3-phase-unit maximum
torque is always referred to as phase-to-neutral.
∆Test current for other than nominal torque
angle setting should be:
(12)
where β= new maximum torque angle.
–————–—| Example6 |———–———
For θm= 75°, Itest = 7 amp.
Relay Range 0.2 - 4.5 .75 - 21.2 1.3 - 3.6
V1F-2F = V2F-3F 15 30 30
∆IT Test Current 13 7 4
Adjust P3for Max.
Torque angle, θm
(Nominal if necessary) 60˚ 75˚ 75˚
θ1θ2 +()
2
----------------------- 30–
IθITθm
sinβsin
----------------------=
if β= 60°
new Itest =
Increasing P3value increases maximum torque an-
gle, and, conversely, decreasing the P3value results
in smaller angle.
For lower maximum torque angle adjustment below
70 degrees, for medium and long ranges, and for
short range for settings below 55 degrees move red
lead on fixed phase-shifting resistor R3, to the oppo-
site terminal; where R3 is adjustable resistor use it in
combination with P3setting without moving the lead.
14.6 Contact Adjustment
14.6.1 KD-10 Relay
With moving-contact arm against right-hand back-
stop, screw the stationary contact in until it just
touches the moving contact. (Check for contact by
using an indicator lamp.) Then back the left-hand
contact out two-thirds of the turn to give 0.020-inch
gap between contacts.
14.6.2 KD-11 Relay
With moving-contact arm against right-hand side of
the bridge, screw the right-hand contact in to just
touch the moving contact and then continue for one
more complete turn. Adjust left-hand contact as de-
scribed above, except back off one turn to give ap-
proximately 0.031 inch gap.
14.7 Spring Restraint
Reconnect for a three-phase fault, Test No. 1 and
set the phase-shifter so that the current lags the volt-
age by:
Adjust the spring so that the current required to close
the left-hand contact is as follows:
90˚ for .2 - 4.5 range
105˚ for .75 - 21.2 and 1.27 - 36.6 ranges
Relay Range 0.2 - 4.5 .75 - 21.2 1.3 - 36.6
V1F-2F = V1FV3F 2.5 10 10
Itrip KD-10 1.55- 1.65 1.22 - 1.28 .710 - .750
Itrip KD-11 1.55 - 1.65 1.22 - 1.30 .710 - .765
775°sin×60°sin
--------------------------- 7.8 amps=
I
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