Type 8311

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5.

Product operation

5.1. Measuring principle

The core element of all pressure transmitters is the pressure measuring cell. The transmitter/switch 8311 uses a piezo-resistive ce-

ramic cell and work following the piezoresistive principle.

The pressure sensor is composed of 4 resistors in a Wheatstone bridge design. The resistive elements, which constitute a strain

gauge, are implemented on a metallic/ceramic diaphragm.

Applying pressure to the diaphragm results in a resistance change in the strain gauge in direct proportion to the applied pressure.

Applying a constant voltage to the wheatstone bridge results in a pressure proportional signal on the output side of the bridge.

5.2. Functional overview

Display and operating keys

The display is used to:

• read the value of certain parameters e.g. the measured pressure, the value of the output current (transmitter version), the pro-

grammed switching thresholds (switch version)…

• parameters of the device by means of 3 keys

Display and operating keys

No. Description

1

4

3

5

2

1

“Back” key:

• to change the value (0…9) of the selected digit

• to go back to the previous function

2

“Next” key:

• to select the digit at the left

• to go to the next function

3

“Confirm” key:

• to confirm the function displayed

• to confirm the parameters set

4

Status LED of transistor output (LED ON = contact closed)

5

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