Schweitzer Engineering Laboratories SEL-311A, Instruction Manual

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Date Code 20011205 Testing and Troubleshooting 13-41
SEL-311A Instruction Manual
° Ð =
° Ð =
° - Ð =
0 . 0 0 . 0 I
0 . 0 0 . 0 I
42 . 82 5 . 2 I
C
B
A
( )
amps 42 . 82 83 . 0 I
amps 42 . 82 5 . 2 I
2
3
1
2
° - Ð =
° - Ð × =
Using Equation 13.1 to calculate Z2, the result is:
( ) ( )
ohms 91 . 2 FT 2 Z
47 . 15 25 . 0 77 . 0 25 . 1 FT 2 Z
ohms 47 . 15 m 2 Z
ohms 66 . 10 c 2 Z
- =
× - × =
=
- =
The relay example Z2F setting is 0.77
W
. Z2c applied (-10.66
W
) is less than the
Z2FT threshold (-2.91
W
), therefore, the 32GF element asserts when these signals
are applied. If Z2c applied is greater than the Z2FT threshold, select new test current
and voltages using the steps outlined above.
Step 5. Turn on the voltage sources. Apply V
A
, V
B
, and V
C
at the magnitudes and angles
listed in Table 13.4. Turn on the current test source. Set the current angle to -82°.
Slowly increase the magnitude of current applied until the Z2G element asserts,
causing OUT106 to close. This occurs when current applied is approximately 2.5
amps.
You may wish to test the distance element characteristic at impedance angles other
than the line positive-sequence impedance angle. To do this, you must adjust the
magnitude and angle of I
TEST
from the values shown in Table 13.4. As an example,
calculate the current signal necessary to test the distance element at an angle of
38.97°.
First, the new desired impedance angle (38.97°) is 45° less than the original test
impedance angle (83.97°). Add 45° to the angle of I
TEST1
.
° - = Ð
° + ° - = Ð
° + Ð = Ð
97 . 128 I
45 97 . 173 I
45 I I
2 TEST
2 TEST
1 TEST 2 TEST
Calculate the magnitude of I
TEST2
using Equation 13.10.
( )
sec , amps
Angle Impedance Test New Angle Impedance Line cos
I
I
1 TEST
2 TEST
-
=
( )
( )
amps 54 . 3 I
amps
45 cos
5 . 2
I
amps
97 . 38 97 . 83 cos
5 . 2
I
2 TEST
2 TEST
2 TEST
=
°
=
° - °
=
Equation 13.10