Omega TX90A Series, User Manual

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SECTION 1 GETTING STARTED
1.1 Unpacking
Remove the packing list and verify that you have received all equipment. If you have
any questions, contact the nearest Customer Service Department, as listed on the
cover of this manual.
Upon receipt of shipment, inspect the container and equipment for any signs of
damage. Note any evidence of rough handling in transit. Immediately report any
damage to the shipping agent.
Note: The carrier will not honor any claims unless all shipping material is saved for
their examination. After examining and removing contents, save packing materials
and carton in the event reshipment is necessary.
1.2 Safety and EMC Considerations
This instrument is a Class III device (8 to 50 Vdc).
Always use a power supply, which complies with EN 60950 safety standard.
••
Do not expose the transmitter to rain or condensing moisture.
••
Do not operate the transmitter in flammable or explosive atmosphere.
•• As with any electronic instrument, you may encounter high voltage exposure
when installing, calibrating or removing parts of the transmitter.
EMC Considerations
••
Whenever EMC is an issue, always use shielded cables.
•• Never run signal and power wires in the same conduit.
••
Use signal wire connections with twisted-pair cables.
•• Install Ferrite Bead(s) on signal wires close to the instrument if EMC problems
persist.
Failure to follow all instructions and warnings may result in injury!
1.3 General Description
The TX91A Series transmitter accepts thermocouple sensor types J, K, T, and E and
will produce a standard 4-20 mA output signal proportional to that produced by its
attached thermocouple millivolt input. The transmitter does NOT provide isolation
between its input and the 4-20 mA output; therefore, an ungrounded thermocouple
junction is suggested to prevent possible ground loops.
The transmitter provides cold reference junction compensation for the thermocouple
types as well as amplification, common-mode rejection and controlling the current
drawn from an 8-to-50 Vdc source to produce the 4-to-20 mA output signal. As
much as 800 ohms dropping resistance may be used in the power leads of the
TX91A when the unit is energized from a 24 Vdc source because of the small
compliance voltage needed by the unit.
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