Backward Path (Bkcal_Out); Lockval And Hystval - GE FVP110 Maintenance Manual

Backward Path (BKCAL_OUT)

In areas outside the endpoints (i.e., start and stop points) of each operation
characteristic, the output is retained at the Y value at the nearer end point. For OUT_1,
however, depending on the setting of LOCKVAL, it is possible to:
Set the value of OUT_1 to Y11 in the areas outside the endpoints if SP is greater
than X12 and if LOCKVAL is false.
When this action is enabled, the value set in HYSTVAL serves as hysteresis, which
affects the output as follows (Figure 65):
When SP has increased beyond X12, OUT_1 is set to Y11.
Then, after SP has decreased below X12 minus HYSTVAL, OUT_1 returns to follow
the set characteristic.
When both downstream blocks of the OS block are ready for cascade connection, the
OS block connects the block on the side of OUT_1 first. For bumpless mode change on
the side of OUT_2, the balancing time for connection can be set in BAL_TIME. When
either downstream block alone is ready for cascade connection, the OS block connects
it and enters the Cas mode. When neither downstream block is ready for cascade
connection, the OS block mode is set to IMan.
Backward Path (BKCAL_OUT)
The value of SP or a value calculated from the value of either BKCAL_IN_1 or
BKCAL_IN_2, depending on the handshake status with the downstream blocks, is
output through BKCAL_OUT. In normal operating conditions (i.e., BLK_MODE.actual is
Cas or Auto), BKCAL_OUT is set to the value of SP.
Figure 65 LOCKVAL and HYSTVAL
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OS Function Block