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7-30
Maintenance and Testing
Date Code 20011026
SEL-321/321-1 Instruction Manual
Because Z2F is positive, use Equation 7.4 to calculate Z2FT.
(
)
(
)
ohms
77
.
0
FT
2
Z
77
.
0
•
25
.
0
77
.
0
•
25
.
1
FT
2
Z
m
2
Z
•
25
.
0
F
2
Z
•
25
.
1
FT
2
Z
=
−
=
−
=
The 32QF element asserts when Z2c is less than Z2FT. As the magnitude of I
A
is
increased, the magnitudes of Z2c and Z2m decrease. For magnitudes of I
A
less than
23.4 amps, 32QF should not assert, given the other test quantities. For I
A
magnitudes
greater than 23.4 amps, Z2c applied is less than Z2FT, so 32QF asserts.
Step 5.
Turn on the voltage sources.
Apply:
°
∠
=
°
∠
=
°
−
∠
=
°
∠
=
96
A
0
.
0
I
120
V
0
.
67
V
120
V
0
.
67
V
0
V
0
.
49
V
A
C
B
A
Slowly increase the magnitude of I
A
, without varying the phase angle.
The relay 32QR element asserts, closing OUT8 when
│
I
A
│
= 0.5 amps. This
indicates that Z2c applied is greater than Z2RT, 3I
2
is greater than 50QR, and I
2
is
greater than a2
⋅
I
1
, where a2 is the relay setting.
Continue to increase the magnitude of I
A
. 32QR deasserts when
│
I
A
│
= 3.3 amps,
indicating that Z2c is now less than Z2RT. 32QF asserts, closing OUT7 when
│
I
A
│
= 23.4 amps, indicating that Z2c is less than Z2FT.
Verify that the relay operated properly by calculating Z2c using Equation 7.2 and the
test quantities listed below.
For:
°
∠
=
°
−
∠
=
°
∠
=
°
∠
=
120
V
0
.
67
V
120
V
0
.
67
V
0
V
0
.
49
V
96
A
30
.
3
I
C
B
A
A
°
∠
=
°
∠
=
°
∠
=
97
.
83
1
ANG
1
Z
1
10
.
1
I
180
V
0
.
6
V
2
2
Summary of Contents for SEL-321
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Page 171: ...Date Code 20011026 Event Reporting 4 9 SEL 321 321 1 Instruction Manual ...
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