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I.L. 41-490H
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 V
voltage.
PH1-PH2
The impedance measured by the 3-phase unit in test
1 (Figure 26) is
V
L L
ZR
=
---------------- -
1.73I
where V
is the phase-to-phase voltage and I
L-L
the test current; similarly, in tests 5, 6 & 7 of Figure
26 the phase-to-phase unit measures.
V
L L
ZR
=
---------------
2I
With phase-shifter set at maximum torque angle
(θ
).
m
(
)
3 phase
I
=
test
(
Θ Θ
)
I
–
test
When testing the 3-phase unit, phase-shifter set-
tings are always set for 30
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.
16
Courtesy of NationalSwitchgear.com
–
(14)
L
is
L
–
(15)
L
V
L L
–
(16)
------------------ -
1.73Z
R
V
LL
=
----------
(17)
2Z
R
°
higher than nominal
At any other angle α, relay reach is
(
θ
cos
Z
=
Z
θ
m
where Z θ = relay reach at maximum torque angle
θ
m.
Test current Iα is calculated as
I
θm
Iα
=
------------------------------- -
(
θ
cos
m
I θ
= test current at
m
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.
Relay Range
.2-4.5
T, T
, T
, T
, T
1.23
A
B
B
C
M, M
, M
+.15
A
C
1.0
S, S
, S
A
C
1.07
Z ohms
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
V
= 50 volts V
= 2 volts: connect current
1F2F
2F3F
lead "23" to "terminal 15, and current lead "22" to
lead marked "21". Set phase-shifter for current to lag
°
V
voltage by 30
this current connection is
1F2F
equivalent to phase B current lagging V
°
by 60
in the reverse directions. Adjust current for
α
)
(18)
–
(19)
α
)
–
θ
m
.75-21.2
1.3-36.5
5.8
10.0
+.15
+.15
1.0
1.0
5.04
8.7
voltage
BN
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