Masoneilan SVI II AP Installation and Maintenance ... - GE Energy

Configure Menu
Using the Digital Interfaces
ATO / ATC
WARNING
This procedure can cause the valve to move. Before
proceeding be sure the valve is isolated from the process.
Keep hands clear from moving parts.
Valve Characteristics
Pressure Units
The positioner must be configured as Air-to-Open, ATO, or as Air-to-Close, ATC. This
parameter is toggled by the * button. If the positioner has a double acting relay, the
action is defined for the output labeled ACT1, or Output 1.
To determine if a direct acting positioner is considered ATO or ATC perform the
following test:
1. Apply the actuators rated pressure to the positioner supply. Do not exceed actuator
pressure rating on the control valve specification sheet. Damage to the valve stem,
shaft, or trim can occur.
2. Disconnect the electrical (4 to 20 mA) input signal from the positioner or set it to less
than 3.6 mA.
3. Observe the position of the control valve. If it is closed the actuator is ATO. If the
valve is open it is ATC.
The positioner must be configured to supply the correct relationship between input
signal and valve position. This is called the position characteristic. Figure 10 on
page 79 lists configuring the positioner characteristics.
Use of a linear characteristic is recommended unless the process dynamics or control
valve application calls for an alternate characteristic. SVI II AP offers a custom
characteristic for specialty applications. Prior to selection of custom, the 10 parameters
for the custom characteristic must be entered using ValVue.
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
HART Handheld communicator.
1. Press * to move from PSI to BAR to KPA.
2. Press + to continue to scroll through the config menu.
NOTE
The characteristic configured in the positioner is applied in
addition to the plug characteristic built into the valve trim. Do
not configure a percentage characteristic if the valve has a
percentage plug.
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