7-44
Maintenance and Testing
Date Code 20011026
SEL-321/321-1 Instruction Manual
°
∠
=
°
∠
=
°
−
∠
=
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
°
−
∠
=
°
−
∠
⋅
=
Using Equation 7.2 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
Ω
. Z2c applied (-10.66
Ω
) is less than the
Z2FT threshold (-2.91
Ω
), therefore, the 32QF 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 7.4. 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 OUT7 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 7.4. 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
.
°
−
=
∠
°
+
°
−
=
∠
°
+
∠
=
∠
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 7.11.
(
)
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
7.11
Summary of Contents for SEL-321
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