Masoneilan SVI II ESD, Installation And Maintenance Manual

Page: 102 / 220

© 2017 Baker Hughes, a GE company, LLC. All rights reserved.
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BHGE
Notes on Aggressiveness
HART
®
Handheld Communicator
The HART
®
handheld communicator is a universally available tool that provides the same
accessibility as the local button and display. The HART
®
tool has the functionality to upload
and download configurations, enter alphanumeric messages and set the custom
characteristic numerical parameters. The GE DPI620 is approved for Intrinsically Safe use in
Hazardous Areas in accordance with SVI II ESD Approvals.
ValVue ESD
ValVue ESD combines the power of the PC with the features of SVI II ESD for ease of use and
automation of positioner operation giving full access to all data. ValVue ESD is provided with
all SVI II ESD positioners and is recommended for set up, service and maintenance where a PC
or laptop is permitted. See “Configuring with ValVue ESD” on page 97 for further information.
Setting Aggressiveness While the SVI II ESD software and the DD allow you to set Aggres-
siveness, the pushbuttons do not. In all three methods, however,
the Aggressiveness value is inherited from any previously per-
formed tuning (Autotune or manual). Once Aggressiveness, and
other tuning values are determined, they are stored in NVRAM.
The SVI-IIAP provides a user define Aggressiveness Level for
auto-tuning, the allowable range varies from -9 to +9 where 0
(Zero) is consider normal tuning. The Aggressiveness Level influ-
ences stroking speed and over-shoot. A negative value will SLOW
stroking speed and help minimized over-shoot. A positive value will
INCREASE stroking speed and may add some over-shoot. The rec-
ommended values for Aggressiveness is 0 for control valves with-
out volume boosters.
In applications with volume boosters and/or quick exhaust valves
are used the Aggressiveness Level is not as influential. For
Auto-tuning it is usually between 0 and 3. Reduce the volume
boosters sensitivity by opening the integral bypass needle valve
about 1 to 2 turns. Use caution when adjusting the needle valve so
as to not to damage the seat, close gently to seat and then open 1
or 2 turns.
Aggressiveness Dynamic Lower values of aggressiveness lead to lower PID values and
slower response and less overshoot.
Higher values lead to higher PID values and quicker response and
more overshoot.
Once you have a preferred aggressiveness and you tune once, all
future autotunes automatically use that same value, until
user-changed.