Date Code 20010731
Breaker Logic
3-37
SEL-352-1, -2 Instruction Manual
The 59L Relay Word bit must be picked up prior to the flashover condition. Use the same
criteria to set the 59L for the flashover logic as for the live bus or line conditions. A
recommended setting is 59L = 57 V.
Flashover Scheme Selection (FOLOG)
Range:
OFF, 1, 2, CUSTOM
Use
SET <ENTER>
to access the FOLOG setting. Select one of two predefined flashover
schemes, select a custom scheme, or disable flashover protection.
The SEL-352 Relay provides two different protection schemes for breaker flashover conditions.
Refer to Figure 3.21
and Figure 3.22 for logic diagrams of each scheme. Setting considerations
for each scheme follow.
If you do not want flashover protection, set FOLOG = OFF. If your application requires
different logic than that available from either of the two schemes, set FOLOG = CUSTOM.
When CUSTOM is selected, all flashover settings are shown including the SEL
OGIC
control
equations. Modify these settings to meet your specific application needs.
Scheme 1 is designed for applications that have voltage measurements on both sides of the
breaker. Scheme 2 is designed for applications where voltages are only available on one side of
the breaker, but the breaker status input is also necessary.
Flashover Pending Failure (FPpu)
Range:
0–16383 cycles in 1/4-cycle steps
Use
SET <ENTER>
to access the FPpu setting and determine the delay before the 62FP timer
expires and asserts the timer output FPAD. Assertion of this output results in assertion of the
FOPF (pending failure) Relay Word bit.
Set flashover pending failure timer setting FPpu at some value shorter than the FFpu setting.
The value for FPpu is based on the breaker operate time and the time calculated for FFpu. If you
use the FPpu to energize a second trip coil, the FOPF bit should assert in enough time to let the
breaker operate before tripping the lockout relay with the FOBF bit.
Flashover conditions require that the breaker is open as indicated by the 87FO element (Scheme
1) or the 52A status (Scheme 2). By tripping the breaker prior to energizing the lockout relay,
you avoid clearing the bus for an incorrect indication of an open breaker. This FOPF trip output
must not energize the TRIPA, TRIPB, or TRIPC inputs, or the flashover logic is defeated.
The recommended setting for FPpu is the FFpu time minus the nominal breaker operate time and
some margin, FPpu = 25 cycles.
Содержание SEL-352-1
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