Date Code 20011026 Maintenance and Testing 7-53
SEL-321/321-1 Instruction Manual
()
[]
2
2
22
I
*IANG1Z1VRe
c2Z
⋅°∠⋅
=
Equation 7.2
2
2
I
V
m2Z
=
m2Z25.0F2Z25.1FT2Z ⋅−⋅= Equation 7.4
Taking the test signals from Table 7.6.
°∠=
°−∠=
°∠=
120V0.67V
120V0.67V
0V0.40V
C
B
A
()
volts1800.9V
volts1200.6712011200.67240100.40V
2
3
1
2
°∠=
°∠⋅°∠+°−∠⋅°∠+°∠⋅=
°∠=
°∠=
°∠=
0.00.0I
0.00.0I
0.00.8I
C
B
A
()
amps0.067.2I
amps0.00.8I
2
3
1
2
°∠=
°∠⋅=
Using Equation 7.2 to calculate Z2c, the result is:
() ()
ohms12.0FT2Z
37.325.077.025.1FT2Z
ohms37.3m2Z
ohms37.3c2Z
=
⋅−⋅=
=
−=
The relay example Z2F setting is 0.77 Ω. Z2c applied (-3.37 Ω) is less than the
Z2FT threshold (0.12 Ω), therefore, the 32QF element should assert 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 7.6. Turn on the current test source. Set the current angle to 0.0°.
Slowly increase the magnitude of current applied until the Z2G element asserts,
causing OUT7 to close. This occurs when current applied is approximately 8.0
amps.
Note: As you perform this test, other protection elements may assert, causing the relay to
close other output contacts and assert relay targets. This is normal and is not a cause
for concern.
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