Siemens SITRANS LUT400, Operating Instructions Manual

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A5E33329501 SITRANS LUT400 (HART) – OPERATING INSTRUCTIONS Page 23
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Transducers
Temperature sensor
The speed of sound changes as temperature changes. To ensure accurate level
measurement, the SITRANS LUT400 compensates via an external temperature input. All
Siemens EchoMax transducers have an internal temperature sensor for this purpose,
and for the fastest temperature response, Siemens also offers a dedicated temperature
sensor, the TS-3.
If the following conditions apply, a separate TS-3 temperature sensor will ensure
optimum accuracy:
•
the transducer is exposed to direct sunlight (or other radiant heat source)
• the temperature of the atmosphere between the transducer face and monitored
surface differs from the temperature of the transducer
• faster response to temperature changes is required.
To achieve the best performance of temperature measurement in a typical open channel
flow application, the temperature sensor should be shielded from direct sunlight and
mounted half way between the ultrasonic transducer face and the maximum head
achievable in the application. Care should be taken to not obstruct the direct sound path
of the ultrasonic transducer.
Note:
Use a TS-3 Temperature Sensor only. Leave terminals open (unused) if TS-3
is not deployed.
Warning: Hazardous voltage present on transducer terminals during
operation.
Notes:
• Do not connect coaxial cable directly to SITRANS LUT400 due to high voltage
transmitted on shield of coaxial cable
• Do not connect the LUT400 shield and white transducer wires together; wire to
separate terminals
• Disregard older transducer manuals that recommend these practices
TRANSDUCER
WHT
1 4 2 5 3
BLK SHLD
WHT
BLK
TS-3