10-30
Testing and Troubleshooting
Date Code 20020129
SEL-387E Instruction Manual
Step 3.
Purpose: Connect two current test sources to one phase of one winding input.
Method: Connect a current source to the IAW1 input. Connect a second current
source in parallel with the first source to the IAW1 input as shown in
Figure 10.8.
Step 4.
Purpose: Apply fundamental current to pick up the 87R element.
Method: Turn on the first current test source connected to the Winding 1 input
(IAW1) equal to the TAP1 setting multiplied by the connection constant
A shown in Table 10.3. The 87R LED will illuminate once current is
applied to the relay.
Step 5.
Purpose: Apply and ramp fifth-harmonic current to dropout the 87R element.
Method: Turn on the second current source for fifth-harmonic current (300 Hz for
NFREQ = 60 and 250 Hz for NFREQ = 50). Starting at zero current,
slowly increase the magnitude of this second current source until the 87R
element deasserts, causing the 87R LED to completely extinguish. Note
the value of the applied current from the second test source. The current
from the fifth-harmonic source should equal the PCT5 setting divided by
100, and multiplied by the magnitude of the fundamental current source,
±5% and ±0.02 I
nom
.
1
IAW
•
100
5
PCT
)
harmonic
fifth
(
1
IAW
=
(fundamental), ±5% ±0.02 I
nom
Harmonic Restraint
Note: This test requires a current source capable of generating second- and fourth-harmonic
current. This example tests the second-harmonic restraint function. Test the fourth-
harmonic restraint function in a similar way.
Step 1.
Purpose: Verify the second-harmonic restraint percentage.
Method: Execute
the
SHOW
command via the relay front panel or serial port and
verify the percentage of fundamental current that the magnitude of second-
harmonic current must exceed for differential restraint. Enter
SHO
PCT2<ENTER>
.
Step 2.
Purpose: Display the appropriate Relay Word bit on the front-panel LEDs.
Method: Execute
the
TARGET
command (i.e.,
TAR F 87R<ENTER>
). The
SEL-387E Relay now displays the state of several differential elements in the
second row of the front-panel LEDs. The 87R bit is the right-most LED.
Step 3.
Purpose: Connect two current test sources to one phase of one winding input.
Method: Connect a current source to the IAW1 input. Connect a second current source
in parallel with the first source to the IAW1 input as shown in Figure 10.8.