GE Baker Hughes Masoneilan SVI FF, Инструкция по установке и эксплуатации

Страница: 138 / 264

© 2019 Baker Hughes, a GE company, LLC. All rights reserved.
138
|
BHGE
Pressure Units
Select the display units for the optional actuator pressure sensor. The available choices are psi,
bar or kPa. The choice applies to both the local LCD display and to the displays with ValVue or
the a handheld communicator.
Tight Shutoff
Tight Shutoff LO is an optional performance feature that prevents leakage at the closed
position. Without this feature, at the closed position with an input signal of 0%, the valve may
be forced tight against the seat with maximum available actuator force or it may be only
touching the seat with minimum force. In either case, it is under control.
To prevent leakage that can occur in the second case, configure TS LO ON and set a value of
position setpoint below which the actuator applies maximum seating force. As the position
signal drops toward the TS value, SVI FF moves the valve to the TS position value. When the
position reaches the TS value SVI FF applies maximum actuator force.
Tight Shutoff HI is an optional performance feature that prevents leakage at the open
position. Without this feature, at the open position with an input signal of 100%, the valve may
be forced tightly open with maximum available actuator force or it may be only touching the
with minimum force. In either case, it is under control.
To prevent leakage that can occur in the second case, configure TS HI ON and set a value of
position setpoint below which the actuator applies maximum seating force. As the position
signal approaches the TS value, SVI FF moves the valve to the TS position value. When the
position reaches the TS value SVI FF applies maximum actuator force.
For both TS LO and HI, the TS function has 0.5% deadband to prevent chatter. If TS is set ON at
2%, for example, then the valve begins to open when the setpoint reaches 2.5%.
These features are implemented by FINAL_VALUE_CUTOFF_LO or FINAL_VALUE_CUTOFF_HI.
In all cases, tight shutoff is engaged when:
1. the setpoint is below (or above for tight open) the configured
threshold, and
2. the valve position is within 5% of that threshold.
See Appendix H “Notes on Characterization” on page 199 for a
discussion of the impact of Characterization on Tight Shutoff
settings.
NOTE
NOTE