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

GE Oil and Gas
SVI II AP Instruction Manual
Isolators
Another solution is to use an Intrinsic Safety Isolator for each loop as shown in Figure 67
on page 119. A number of manufacturers make suitable isolators designed for use with
HART output circuits. Using an IS Isolator allows up to three SVI II AP to be operated
from a single 4 - 20 mA DCS output. Each isolator has a low compliance voltage input
requirement and a high voltage output capacity.
Up to three isolators can be connected in series to a single controller output and each of
them can drive a positioner. Isolators are used to provide compliance voltage and
isolation even in installations not requiring intrinsic safety. An example of an isolator can
be obtained from R. Stahl, (Model 9318/16-22-10). Consult the manufacturer for detailed
installation instructions.
The HART loop address of each device must be set to 1, 2, and 3 (or other non-zero
values) to allow a HART master to recognize each SVI II AP when connected to all three
devices on the safe area side of the multiple isolators. Do not use 0 for any of the
positioners. A 0 causes HART masters to stop searching for additional positioners.
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