Siemens SITRANS P Instruções de Operação descarregar pdf (Página 127)

Example of an application

The

current is to be measured as a voltage drop from 1 to 5 V at a resistance of 250 Ohm +/-

5%. To trim the tolerance of the resistance, set the current transmitter so that the voltage drop

at 4 mA is exactly 1 V and at 20 mA is exactly 5 V.

● Trim at 4 mA:

Use the current transmitter trim menu option to instruct the transmitter to output 4 mA. Read

the measured value at an ammeter and input it. The transmitter uses this value for offset

correction of the current.

● Trim at 20 mA:

Use the current transmitter trim menu option to instruct the transmitter to output 20 mA.

Read the measured value at an ammeter and input it. The transmitter uses this value for

gradient correction of the current. The value for 4 mA is not affected by this.

Note

If a multimeter is used, it must always be sufficiently accurate.

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A Original characteristic

B Characteristic curve after current transmitter trim 4 mA

C Characteristic curve after current transmitter trim 20 mA

Figure 7-15 Current transmitter trim

7.18

Factory calibration

Introduction

You can use factory calibration to reset the transmitter to the factory state.

Operating functions through HART

7.18 Factory calibration

SITRANS P, DS III series with HART

Operating Instructions, 09/2012, A5E00047092-08 125

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Siemens SITRANS P Instruções de Operação Página 127