Isolators - GE Masoneilan SVI II ESD Installation And Maintenance Manual

Isolators

Another split range solution is achieved by means of an Intrinsic Safety Isolator for each loop
as shown in Figure 86 on page 183. Several manufacturers supply suitable isolators designed
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for use with HART output circuits. Using an IS Isolator allows up to three SVI II ESDs to
operate 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. Consult the manufacturer for detailed installation
instructions.
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The HART loop address of each device must be set to 1, 2, and 3 (or any non-zero values) to
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allow a HART master to recognize each SVI II ESD 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
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HART masters to stop searching for additional positioners.
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