Baker Hughes Masoneilan SVIII AP, Installation And Maintenance Manual

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Masoneilan SVI II AP Installation and Maintenance Manual =
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Split Range Applications
The SVI II AP is designed to operate in split range configurations supporting up to three
control valves connected to a single controller output. Minimum input current span for each
SVI II AP is 5 mA. For each positioner the upper range value is between 8 and 20 mA and the
lower range value is between 4 and 14 mA. For example, three devices might be configured
with input current ranges of 4 - 9 mA; 9 - 14 mA, and 14 - 20 mA. Split range operation with
SVI II AP requires special consideration of the compliance voltage. The SVI II AP requires at
least 9.0 V. Two SVI II AP in series requires at least 18.0 V in addition to the voltage drops in
wiring and other series devices. Typical controller output current sources rarely deliver 24 V,
so the system can become voltage starved. It is possible to boost the compliance voltage of
the DCS using a series wired voltage source power supply, as shown in Figure 47 on page 120.
The total loop voltage must not exceed the rating for the controller output current source.
Contact the DCS vendor to validate this approach.
See “Determining an SVI Positioner Compliance Voltage in a Control System” on page 199.
NOTE
The internal electronic components are isolated from ground.
Grounding the case is unnecessary for functional purposes.
Grounding the case may be necessary to conform to local codes.