Technical Specifications

ValVue Digital Communications Software Ver. 2.80
236
GE Oil & Gas
Bumpless Transfer
Use the checkbox to select/deselect this option.
This option provides a means to maintain smooth valve control positioning when changing to
Normal mode from Manual or Setup. Without Bumpless Transfer, when changing to Normal
mode, the setpoint could vary in a manner that causes a significant process disturbance.
Bumpless Transfer moves the controller signal to match the valve position so that smooth
resumption of control with little disturbance results.
When Bumpless Transfer is selected, returning to Normal mode from Manual or Setup mode is
deferred until the input signal matches the current valve position. Either the input signal or the
valve position can be changed to match. If nothing is done, the system slowly changes the
position until it matches the signal setpoint. The time taken to move to the position is
determined by the Transfer Time which is a number between 0 and 255 and is approximately
the number of seconds required to move the valve 100%.
Position Limits
Allow Diagnostics to Over-
ride Limits
A checkbox for enabling/disabling autotuning and diagnostics to
override limits.
Tight Shutoff Below (%) Use this checkbox to enable/disable the use of Tight Shutoff’s value.
Activates a tight shutoff below the value in the field. If the input sig-
nal would position the valve below the Tight Shutoff value, then air is
supplied to fully seat the valve. Range: –1 and 20%.
Position Lower Limit Use this checkbox to enable/disable the use of the value in the field.
Activates a software limit stop. No valve position lower than this
occurs when enabled. This is software only. During electrical/air fail-
ure, the valve moves to failsafe position. This stop is ignored during
manual full open or close operations.
Position Upper Limit Use this checkbox to enable/disable the use of the value in the field.
Activates a software limit stop. No valve position higher than this
occurs when enabled. This is software only. During electrical/air fail-
ure, the valve moves to failsafe position. This stop is ignored during
manual full open or close operations.
Position Rate Limits Click either/both boxes to activate a field to the right. Enter a value in
%/second which is the time used for travelling full span.
NOTE If you configure both Bumpless Transfer and Position Rate Limits
and the Bumpless Transfer settings is significantly greater than
the Position Rate Limits, a dialog appears. You can click OK and
continue, but in effect, the Bumpless Transfer is ignored in favor of
Position Rate Limits.