Date Code 20020129
Testing and Troubleshooting
10-29
SEL-387E Instruction Manual
Step 5.
Purpose: Apply and ramp second-harmonic current to dropout the 87R element.
Method: Turn on the second current source for second-harmonic current (120 Hz for
NFREQ = 60 and 100 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 second-harmonic source should equal the PCT2 setting divided by 100,
multiplied by the magnitude of the fundamental current source, ±5% and
±0.02 I
nom
.
1
IAW
•
100
2
PCT
)
harmonic
ond
(sec
1
IAW
=
(fundamental),
±5% ±0.02 I
nom
Figure 10.8: Test Connections for Parallel Current Sources
Fifth-Harmonic Blocking
Note:
This test requires a current source capable of generating fifth-harmonic current. This
example tests the fifth-harmonic blocking function.
Step 1.
Purpose: Verify the fifth-harmonic restraint percentage.
Method: Execute
the
SHOWSET
command via the relay front panel or serial port
and verify the percentage of fundamental current that the magnitude of
fifth-harmonic current must exceed for differential restraint. Enter
SHO
PCT5<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.
