Schweitzer Engineering Laboratories SEL-311C - Table 13.5 Test Quantities for Zone 2 Phase Distance Element

13.35
Date Code 20060320 Instruction Manual SEL-311C Relay
Testing and Troubleshooting
Test Procedures
Step 8. Connect the voltage sources to the relay A-phase, B-phase, and
C-phase voltage inputs.
Step 9. Connect the current source to the relay B-phase and C-phase
current inputs. Refer to the voltage and current connections
shown in Figure 13.6 as an example.
Step 10. Select the magnitude of the test signals, I
BC
, V
B
, and V
C
.
Table 13.5 summarizes the test quantities for the Zone 2 B-C
phase distance element based upon the example relay settings.
The following text describes a hand calculation method you can
use to calculate relay distance element voltage and current test
signals. If you do not want to review this information, go to
Step 19.
The relay phase distance elements operate based upon the
magnitude of applied phase-to-phase impedance. The
impedance calculation is also supervised by the functions
described. To effectively test the distance elements, select
voltage and current test signals that fulfill the impedance and
supervisory requirements of the relay settings, but are within
the ability of the voltage and current test sources to produce
accurately.
The Zone 2 phase distance element is forward-reaching. Thus,
it is supervised by the forward directional element 32QF, as
well as the 50PP2 phase-to-phase overcurrent elements. For the
distance element to assert, the applied phase-to-phase current
must exceed the 50PP2 setting and applied 3I
2
must exceed the
50QF setting.
The 50PP overcurrent elements operate based upon the
magnitude of the vector difference between any two phase
currents. Using the current connections shown in Figure 13.6,
the magnitude of I
BC
is twice the magnitude of the applied
current. This is illustrated by the following equations.
Equation 13.33
With a 50PP2 setting of 2.22 amps, 50PP2 picks up when I
TEST
is greater than 1.11 amps.
The 50QF negative-sequence overcurrent element operates
based upon the magnitude of 3I
2
applied. Using the current
connections shown in Figure 13.6, we can calculate the
magnitude of 3I
2
applied based upon the magnitude of I
TEST
.
Table 13.5 Test Quantities for Zone 2 Phase Distance Element
Test Vo l tages Te s t Cur re n t
V
A
= 67 ∠0° volts I
TEST
= 2.5 ∠–173.97° amps
V
B
= 46.8 ∠–150° volts
V
C
= 46.8 ∠150° volts
I
TEST
I
B
I
C
–==
I
BC
I
B
I
C
–=
I
BC
2I
B
• =
I
BC
2I
TEST
• =