P.11.36
SEL-411L Relay Protection Manual Date Code 20151029
Testing and Troubleshooting
Checking Relay Operation
One way to create a V
BC
phasor is to equate |V
B
| and |V
C
| and determine the
appropriate angles to make an equilateral triangle as shown in Figure 11.17.
Subtract 30 degrees (angle
1
) from 180 degrees to obtain the angle for test
source V
C
phasor
;
V
C
= 46.8 150 V.
Similarly, add 30 degrees (angle
2
) to –180 degrees to obtain test source V
B
phasor; V
B
= 46.8 –150 V.
Test voltage V
A
can be the nominal value, V
A
= 67 0 V.
Thus, the resulting phase-to-phase voltage is V
BC
= 46.8 –90 V, referenced
to the V
A
phasor at 0 degrees.
The relay measures phase distance element maximum reach when the faulted
phase-to-phase current lags the faulted phase-to-phase voltage by the distance
element maximum torque angle. The phase distance element maximum torque
angle is setting Z1ANG. Current I
BC
should lag voltage V
BC
by Z1ANG.
In this example, Z1ANG is 84.0 degrees. From Equation 11.19, the angle of
I
B
is the angle of I
TEST
, and the angle of I
C
is 180 degrees from the angle of
I
TEST
. The test source current for I
B
is the following:
Equation 11.23
And the test source current for I
C
is the following:
Equation 11.24
Checking the MBC2 Portion of the Z2P Phase Distance Element
The following procedure describes how to test the B-phase to C-phase
distance element MBC2. Although this test refers directly to the Zone 2 phase
distance element, you can apply this procedure to any other forward-reaching
phase-to-phase distance element zone.
This example assumes that you have successfully established communication
with the relay (see Making an EIA-232 Serial Port Connection on
page P.10.5). In addition, you must be familiar with relay access levels and
passwords (see Changing the Default Passwords on page P.10.6 to change the
default access level passwords and enter higher relay access levels). You
should be familiar with
ACSELERATOR QuickSet (see Section 6: PC
Software).
Step 1. Configure the relay.
Perform the procedure listed under Step 1 in Checking the
Negative-Sequence Directional Element (Phase Faults).
Step 2. Set test values in the relay.
Perform the procedure listed under Step 2 in Checking the
Negative-Sequence Directional Element (Phase Faults).
Step 3. Set the phase distance element reach.
a. Select the Phase Distance button of the
ACSELERATOR
QuickSet Settings tree view.
b. Confirm the settings of E2IMP at 3, Z1MP at 6.24, and
Z2MP at 9.36.
I
B
2.5 –90 Z1ANG–A=
2.5 –90 84–A=
2.5 –174A=
I
C
–I
B
– 2.5 –174A 2.5 6A===
NOTE: As you perform this test,
other protection elements can assert.
This causes the relay to assert other
targets and possibly close control
outputs. Be sure to isolate the relay
from the power system to avoid
unexpected system effects.
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