Dresser Masoneilan SVI II AP, Инструкция по эксплуатации

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SVI II AP Instruction Manual
88
DRAFT 6/
8/10
Dresser Masoneilan
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 Volts. Two SVI II AP in series requires at least 18.0
Volts in addition to the voltage drops in wiring and other series devices. Typical controller
output current sources rarely deliver 24 Volts, 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 43 on page 94. The total loop voltage must not
exceed the rating for the controller output current source. Contact the DCS vendor to
validate this approach.
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.