Woodward ProTech 203, Руководство по эксплуатации

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ProTech 203 Overspeed Protection System Manual 85204
18 Woodward
If the unit is being restarted after a normal rolldown (that is, there was no trip),
the unit does not require a reset. The MPU fail trip is overridden because the
MPU fail timer is cleared whenever speed exceeds the MPU fail set point. The
MPU fail timer should be started by the operator when the turbine is ready to be
started again.
The MPU fail timer can only be started when speed is below the MPU fail set point.
Pressing the start key has no effect if speed is above the MPU fail set point.
Method 2
"TIMER STARTS ON RESET" = "YES". MPU fail timer starts when the reset key
is pressed or remote reset is momentarily closed. An open contact input causes
a trip if speed is below the MPU fail set point, regardless of the timer.
See Figure 4-3 for a block diagram of this method. It is the method used in earlier
versions of the ProTech system. When the turbine is ready to be started, the
MPU fail timer is started by pressing the reset key, or by momentarily closing the
remote reset input. If speed does not exceed the MPU fail set point within the
MPU fail timeout value, the unit trips.
Figure 4-3. Method 2 Block Diagram
If the unit is being restarted after a normal rolldown (that is, there was no trip), it
should be reset when the turbine is ready to be started again. Earlier versions of
the ProTech system remained disabled if the remote reset contact was held
closed. In the present version, holding the remote reset contact closed will not
disable the unit. If the unit is reset to clear a trip condition, but the turbine will not
be immediately re-started, the remote reset contact must be periodically
momentarily closed in order to prevent the timer from causing an MPU fail
timeout trip.
As further protection against a faulty MPU signal to the ProTech system, the
contact input can trip the turbine if the speed sensed by the unit is below the
MPU fail set point, regardless of the timer. The contact input could come from the
turbine control system, or could come from a limit switch, pressure switch, or a
combination of such devices which provide positive indication that the turbine
speed should be above the MPU fail set point.
Compare
Timer
START
CLEAR
EXPIRED
Latch
SET
CLEAR
TRIP
MPU
Contact
Input
RESET
Speed < MPU Fail Setpoint
Speed > MPU Fail Setpoint
Compare
MPU
Fail
Detect
Speed > Trip Setpoint
(Open = TRUE)
MPU Fail
Setpoint
Value
Trip Setpoint
Value
MPU Fail Timeout
Value
AND
AND
OR