Sel 411L - Page 751

P.11.37
Date Code 20151029 Protection Manual SEL-411L Relay
Testing and Troubleshooting
Checking Relay Operation
Step 4. Upload the new settings to the relay.
a. Click File > Send.
b.
ACSELERATOR QuickSet prompts you for the settings
class you want to send to the relay.
c. Click the check box for Group 1.
d. Click OK.
ACSELERATOR QuickSet responds with a dialog box
similar to the second dialog box of Figure 11.16.
If you see no error message, the new settings are loaded
in the relay.
Step 5. Display the MBC2 Relay Word bit on the front-panel LCD
screen.
a. Access the front-panel LCD
MAIN MENU.
b. Highlight
RELAY ELEMENTS and press ENT.
c. You will see a
RELAY ELEMENTS screen with SEARCH
highlighted at the bottom of the screen.
d. Press ENT to go to the
ELEMENT SEARCH submenu of
Figure 11.14.
e. Use the navigation keys to highlight
M and press ENT to
enter character in the text input field.
f. Enter the
B, C, and 2 characters in like manner.
g. Highlight
ACCEPT and press ENT.
The relay displays the LCD screen containing the
MBC2 element.
Step 6. Set the magnitudes and angles of the test signals for a B-phase-
to-C-phase fault.
a. Connect the test sources (with power off) to the relay.
This connection is a B-phase-to-C-phase fault where
I
A
 0 and I
B
= –I
C
.
b. Adjust the voltage sources to provide the following test
voltages: V
A
= 67 V 0, V
B
= 46.8 V –150, and
V
C
= 46.8 V 150.
c. Set the current source for I
B
= 0.0 A –174.
Step 7. Apply the sources to confirm operation of MBC2.
a. Apply the source test current by slowly increasing the
magnitude of I
B.
b. Observe the RELAY ELEMENT LCD screen.
Relay Word bit MBC2 asserts when |I
B
|  2.5 A,
indicating that the relay impedance calculation is less
than the Z2MP reach setting.