Figure 5.2 illustrates the sync-check relay
"
sync-check window.
"
The cross-hatched area is
the region in which the breaker may be closed without fear of damage.
To set the relay, you must know the maximum angle (ø) between VPOL and VS that is
allowed for the breaker to close. The slip frequency should be estimated to set the 25T time
delay and the breaker close time should also be known.
Referring to Figure 5.2, note that 25DV is determined from the known angle, ø. The 25DV
setting is approximated with the equation:
The value of ø should be the maximum angle across the breaker to allow closing.
Figure 5.2: Sync-Check Window
For our example, for a maximum angle of 30° and 59VHI equal to 80% of nominal phase-
neutral voltage on a 230 kV system:
The slip frequency is the maximum allowed frequency difference between VP and VS. The
formula for slip is as follows:
Where 25T is the sync-check time delay from the SEL-221F relay setting.
For example, with 25T = 5 seconds and ø = 30°:
5-10
Applications
SEL-221F, -1 Instruction Manual
Date Code 920508
Summary of Contents for SEL-221F
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Page 69: ...Date Code 920508 Specifications SEL 221F 1 Instruction Manual 2 44 ...
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Page 110: ...Example Event Report 2 4 12 Event Reporting SEL 221F 1 Instruction Manual Date Code 930830 ...
Page 158: ...SETTINGS SHEET FOR SEL 221F RELAY PAGE 2 OF 6 DATE Date Code 921110 ...
Page 160: ...SETTINGS SHEET PAGE 4 OF 6 FOR SEL 221F RELAY DATE Date Code 930601 ...
Page 161: ...SETTINGS SHEET PAGE 5 OF 6 FOR SEL 221F RELAY DATE Date Code 961208 ...
Page 229: ...SEL 200 Series Relay Main Board Troubleshooting Test Points and Jumper Locations ...