Schweitzer Engineering Laboratories SEL-321 - Page 313

Date Code 20011026 Maintenance and Testing 7-43
SEL-321/321-1 Instruction Manual
() ( ) A0kM0k1MG2ZZ0k1Z
TESTAG
∠+⋅==+⋅ Equation 7.15
()
()
°∠=
°−∠⋅°∠=
°−∠+⋅°∠=
42.8215.16Z
55.1725.197.8336.9Z
69.3726.0197.8336.9Z
TEST
TEST
TEST
I
A
must lag V
A
by the angle of Z
TEST
to check the maximum reach of the element
under test. With V
A
applied at an angle of 0°, the angle of I
A
is:
°−∠= 42.825.2I
A
Calculate the magnitude of V
A
using Equation 7.16
ondarysecvolts0.04.40V
42.8215.1642.825.2V
ZIV
A
A
TESTAA
°∠=
°∠⋅°−∠=
⋅=
Equation 7.16
Select
.volts12067Vandvolts12067V
CB
°∠=°−∠=
The ground distance elements are supervised by the negative-sequence directional
element. It is important to check the negative-sequence quantities applied and verify
that the 32QF element should assert allowing the forward-reaching distance element
to operate. Calculate the magnitude and angle of negative-sequence voltage and
current applied for the test quantities listed above. Then calculate the negative-
sequence impedance, Z2c, applied using Equation 7.2 and compare Z2c to the Z2FT
threshold which is a function of the Z2F setting and Z2m.
()
()
CB
2
A
3
1
2
CB
2
A
3
1
2
IaIaII
VaVaVV
⋅+⋅+⋅=
⋅+⋅+⋅=
() []
2
2
22
I
*IANG1Z1VRe
c2Z
⋅°∠⋅
=
Equation 7.2
2
2
I
V
m2Z
=
m2Z25.0F2Z25.1FT2Z ⋅−⋅=
Taking the test signals from Table 7.4.
°∠=
°−∠=
°∠=
120V0.67V
120V0.67V
0V4.40V
C
B
A
()
volts18088.8V
volts1200.6712011200.67240104.40V
2
3
1
2
°∠=
°∠⋅°∠+°−∠⋅°∠+°∠⋅=