Quick Installation Guide | March 2013 |
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Step 3: Connect the wiring
Wiring and power supply requirements can be dependent upon the approval certification. As with all FOUNDATION fieldbus requirements, a conditioned power supply and terminating resistors are required for proper operation.
It is recommended that shielded twisted pair wiring
NOTE:
Avoid running instrument cable next to power cables in cable trays or near heavy electrical equipment.
It is important that the instrument cable shield be:
-trimmed close and insulated from touching the transmitter housing
-continuously connected throughout the segment
-connected to a good earth ground at the power supply end
Grounding
When wiring the transmitters, the grounding should be completed such that:
The loop is grounded at the power supply.
When transmitters are installed on metal tanks, ensure there is a
If the tank is
If the tank is cathodically protected, the housing must be grounded to an earth ground that is outside of the cathodic protection system ground. Use the external terminal for this purpose.
When transient protection terminal block is used, the ground wire should be separate from the signal wire. Use the external ground terminal.
Make sure grounding is done (including IS ground inside Terminal compartment) according to Hazardous Locations Certifications, national and local electrical codes.
The most effective transmitter housing grounding method is a direct connection to earth ground with minimal (< 1 Ω) impedance.
NOTE:
Grounding the transmitter housing using the threaded conduit connection may not provide a sufficient ground. The transient protection terminal block will not provide transient protection unless the transmitter housing is properly grounded. Use the above guidelines to ground the transmitter housing. Do not run transient protection ground wire with signal wiring; the ground wire may carry excessive current if a lightning strike occurs.
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