Wika IUT-11 Manual do Utilizador descarregar pdf (Página 39)

2266939.05 D/GB 06/2006

Universal IS Pressure Transmitter UniTrans

Operation of Devices without Displays

Subject to change due to technical modifications. © Copyright WIKA Alexander Wiegand GmbH & Co. KG / Germany

WIKA Alexander Wiegand GmbH & Co. KG · Alexander-Wiegand-Str. · 63911 Klingenberg ·  (09372) 132 - 710 · Fax - 706 · E-mail: sup[email protected] · www.wika.de

114

8.4 Calibration without Pressure

Determine the current reference values for the zero point and the span to be entered

in the transmitter before calibration. This is done as follows:

8.4.1 Zero Point Calibration

• Determine the hydrostatic pressure of the liquid’s surface that meets the zero point.

• Adjust this pressure in proportion to the sensor’s nominal pressure range.

• Multiply this proportion by 16 mA and add 4 mA to the result.

This produces the calculated current (value I

calc

), which is entered in the transmitter

and used to programm the zero point (0%).

Example:

A pressure transducer with 0 ... 400 mbar (nominal pressure) needs to be pro-

grammed.The liquid’s surface (with a density of 1) is 1 m above the diaphragm at the

zero point producing a pressure of 100 mbar.

This means that the device’s current value must be set to 8 mA when performing a dry

(empty) calibration.

8.4.2 Span Calibration

• Determine the hydrostatic pressure of the liquid’s surface, which corresponds to the

span end-point.

• Calculate the difference of the pressure value between span end-point and zero

point and divide this difference by the nominal pressure range of the sensor.

• Multiply this proportion by 16 mA and add 4 mA to the result.

This produces the calculated current (value I

calc

), which is entered in the transmitter

and used to program the span end-point (100%).

The measurement range between zero point and span end-point will be stored as

span.

calc

Zero point pressure (0%) 100 mbar

Sensors nominal pressure 400 mbar

------------------------------------------------------------------------------------------------

16 mA 4 mA

+⋅ 8 mA==

(2 sec.)

026-DS-GB

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