Endress+Hauser Proline t-mass 65 PROFIBUS DP, Руководство по эксплуатации

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Proline t-mass 65 PROFIBUS DP Installation
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3.2.12 External pressure compensation
An external pressure compensating via PROFIBUS communication is useful in cases where:
• Large variations of pressure are likely to occur e.g. 2 to 8 bar (30 to 120 psi) with air applications
• The thermal properties of the gas are likely to vary e.g. Ammonia gas
Transmission of pressure value via PROFIBUS:
The value of the process pressure can be cyclically transmitted from the PROFIBUS Master (class 1)
to the measuring device by means of the PRESSURE_VALUE module (
→
Page 63).
!
Note!
• A pressure transmitter with an absolute pressure range must be used.
• In-situ calibration is not possible if an external pressure compensation is being used.
In-situ calibration writes a new calibration curve at the actual process condition, pressure
compensation is disabled.
3.2.13 Temperature range
The following requirements and limits must be observed:
• It is recommended to install the sensor out of any direct sunlight or away from any extremes of
temperature.
• The maximum approved ambient and process temperatures (see Page 96 ff.)
• Instructions on heating and thermal insulation (see Page 23 ff.)
3.2.14 Heating
Some gases require suitable measures to avoid loss of heat at the sensor and therefore condensation.
Heating can be electric, e. g. with heated elements, or by means of hot water or steam pipes.
"
Caution!
• Risk of electronics overheating! Consequently, make sure that the adapter between sensor and
transmitter and the connection housing of the remote version always remain free of insulating
material.
• When using electrical heat tracing whose heat is regulated using phase control or by pulse packs,
it cannot be ruled out that the measured values are influenced by magnetic fields which may
occur (i. e. at values greater than those permitted by the EC standard minus 30 A/m). In such
cases, the sensor must be magnetically screened.