10-24
Testing and Troubleshooting
Date Code 20020129
SEL-387E Instruction Manual
SLP1 Restrained Differential Threshold
Step 1.
Purpose: Verify the differential characteristic settings and set winding
compensation.
Method: Execute
the
SHO TAP1<ENTER>
command via the relay front panel or
serial port and verify the (TAPn) settings, the restraint slope 1 percentage
(SLP1) setting, the restraint slope 2 percentage (SLP2) setting, the
restraint current slope 1 limit (IRS1) setting, and the O87P minimum
pickup setting.
Execute the
SET W1CTC<ENTER>
command and set the WnCTC
settings for the two windings to be used to the same value (0, 1, …, 12).
Save the settings.
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: Select a test point on the percentage differential curve in Figure 10.7.
Method: Decide where you want to cross the differential characteristic by picking a
restraint value IRT, which is a vertical line on the graph. Because this test
is for the SLP1 threshold, select a point above the O87P intersection point
and below IRS1. If SLP2 = OFF, IRS1 and SLP2 are not functional.
1
IRS
IRT
1
SLP
100
•
P
87
O
<
<
The value of IOP corresponding to the selected IRT equals the following:
IRT
•
100
1
SLP
IOP
=
Both IRT and IOP are in multiples of tap.