7-4 Maintenance and Testing Date Code 20011026
SEL-321/321-1 Instruction Manual
Step 7.
Purpose: Connect voltage and current sources to the relay.
Method: Turn relay power off. If three voltage sources and three current sources
are available, connect the sources to the relay as shown in Figure 7.3. If three
voltage sources and two current sources are available, connect them as shown in
Figure 7.5. Apply 67 volts per phase (line-to-neutral) in positive-sequence rotation.
Apply 2.0 amps per phase, in phase with the applied phase voltages.
Step 8.
Purpose: Verify correct voltage and current connections and levels.
Method: Turn relay power on. Press the front panel METER button. Use the
arrow keys to examine the METER data. The relay displays the measurements of
the voltages and currents applied in Step 7. With applied voltages of 67 volts per
phase and a potential transformer ratio of 2000:1, the displayed line-to-neutral
voltages should be 134 kV. With applied currents of 2.0 A per phase and a current
transformer ratio of 200:1, the displayed line-to-neutral currents should be 400 A.
All line-to-line quantities should be balanced, differing from the line-to-neutral
measurements by a factor of 1.73. Real power P should be approximately 160.1
MW; reactive power Q should be approximately 0 MVAR.
If you inadvertently switched a pair of voltages or currents, the MW reading should
be approximately zero. It is important to remember this when commissioning the
relay using system voltages and currents.
If you wish to verify the relay voltage and current connections in a more detailed
manner, use the SEL Direction and Polarity Check Form provided in Section 6:
Installation.
Step 9.
Purpose: Use the front panel setting feature to adjust a relay setting.
Method: The following steps are required to change a relay setting from the
SEL-321 Relay front panel:
1. Enter Access Level 2 using the appropriate password.
2. Execute the SET command.
3. Select the setting to change.
4. Make and accept the setting change.
With EN displayed on the relay LCD screen, press the front panel button labeled
OTHER. With 2AC shown on the screen, press SELECT. This instructs the relay
to execute the 2ACCESS command.
In order to enter Access Level 2, you must enter the correct password. The relay is
equipped with a Level 2 password of TAIL. The relay displays a list of characters to
build the password from. Use the Up or Down arrow button to choose the list of
characters containing T. Use the Left and Right arrow buttons to underline the T.
Press SELECT to enter T as the first letter of the Level 2 password.
Next, use the Up or Down arrow button to choose the list of characters containing A,
I, and L. Underline each character in turn and press the SELECT button to enter
each character into the Level 2 password.
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