10-40
Testing and Troubleshooting
Date Code 20020129
SEL-387E Instruction Manual
Step 18.
Purpose: Display the appropriate Relay Word bit on the front-panel LEDs.
Method: Execute
the
TARGET
command (i.e.,
TAR F 24C2T<ENTER>
). The
SEL-387E Relay now displays the state of the volts/hertz elements on the
bottom row of front-panel LEDs.
Step 19.
Purpose: Apply balanced three-phase voltage and change the voltage until the
appropriate LED illuminates.
Method: Apply balanced three-phase voltages as shown in Figure 10.5. Change the
voltage to a value above the
24IP
setting and below the
24D2P2
setting
until the
24C2T
LED illuminates. Refer to
Section 3: Differential,
Restricted Earth Fault, Overcurrent, Voltage, and Frequency Elements
for the maximum inverse-time timing error. Calculate pickup time as:
IC
24
1
%
100
IP
24
10
•
V
NFREQ
•
freq
PTR
•
V
•
3
ITD
24
T
2
C
24
3
nom
sec
Ü
Ü
Ü
Ü
Ü
Ü
Ý
Û
Ì
Ì
Ì
Ì
Ì
Ì
Í
Ë
-
=
V
sec
=
Secondary voltage (applied)
PTR
=
Potential transformer ratio (Setting)
Freq =
Frequency
(applied)
NFREQ =
Nominal Frequency (Setting)
V
nom
=
Nominal Voltage in kV (Setting)
24ITD
=
Inverse time factor (Setting)
24IP
=
Inverse time pickup (Setting)
24IC
=
Inverse time curve (Setting)
Step 20.
Purpose: Verify
the
24D2P2
setting and
24D2D2
delay.
Method: Apply balanced three-phase voltages as shown in Figure 10.5. Change the
voltage from a value below the
24IP
setting to a value above the
24D2P2
setting. The
24C2T
LED should illuminate
24D2D2
seconds later.
Step 21.
Purpose: Verify the Level 2 volts/hertz delay settings, when
24CCS = I
.
Method: Execute
the
SHOWSET
command via the relay front panel or serial port
and verify the setting (i.e.,
SHO 24CCS<ENTER
).