Setting Calculations - ABB KD-10 Instruction Leaflet

Type KD-10 and KD-11 Compensator Distance Relay
to Figure 2 (page 36), 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
(R , or R ) is open circuited. The effect of the
2A 2C
loading resistor, when connected, is to produce an
in te rna l dro p i n th e c o mp en s ato r, w hi c h is
out-of-phase with the induced voltage, IT
Thus the net 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 (page 36). Other angles may be set
by changing resistor R
2A
The maximum torque 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 R
The maximum torque 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 R
gle may be set. The 90-degree setting is approached
for all ranges when R
3
the 3φ unit or R and R
2A
unit.
Tap markings are based upon nominal settings as
specified above. If the phase loading potentiometers
P , P , or P are adjusted for some other maxi-
3 2A 2C
mum torque angle, the relay reach is different from
the nominal as described under settings.
5.0 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 (page 44). 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 (page 45) and Figure 16 (page 45) show
the KD-11 operating time of the phase-to-phase unit
and the three-phase unit respectively. These curves
show both contact-opening time and contact-closing
time for faults within the relay setting.
or IT
AB
and R (or P and P
2C 2A
.
3
(or P ) any other an-
3 3
resistor is open circuited for
for the phase-to-phase
2C
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,
S = 2, T = 10,
S = 3, T = 10,
.
AC
S = 1, T = 7.02, continuous rating is 7 amp
5.3 BURDEN
The burden which the relays impose upon potential
and current transformers in each phase is shown by
).
2C
Figure 17 (page 46) and Figure 18 (page 48) for the
KD-10 and KD-11 relays respectively. The potential
burden and burden phase angle are based on 69
volts line-to-neutral applied to the relay terminals.
5.4 TRIP CIRCUIT CONSTANT
0.2 tap = 6.5 ohms
2 tap = 0.15 ohms

6.0 SETTING CALCULATIONS

Relay reach is set on the tap plate shown in Figure 3
(page 36). The tap markings are:
(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)
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:
0.9 Zpri
Z =
The terms used in this formula and hereafter are de-
fined as follows:
Z = The desired ohmic reach of the relay in
secondary ohms.
continuous rating is 6 amp
continuous rating is 8 amp
continuous rating is 9 amp
T, T , T , and T
A B C
S, S , and S
A
1, 2, 3
M, M , M
A
.0, .03, .09, .06
R
c
------ -
R
V
41-490J
C
C
[Equ. 9]
7