Vega D84 Hydrostatic pressure transmitter Bedienungsanleitung PDF herunterladen (Seite 40)

40 Pressure transmitter D84

Diagnostics

6 Diagnostics

Maintenance

The pressure transmitter D84 is maintenance

free.

Should dismounting of the pressure transmit-

ter (e.g. for vessel cleaning) be necessary,

we recommend the use of new seals. Use

only original seals from VEGA.

Remedying faults

Through continuous self-monitoring, series 80

pressure transmitters offer maximum

reliability. However, if faults occur, please

check the following before removing the

pressure transmitter:

- the atmospheric pressure compensation

(only with gauge pressure measuring

ranges),

- the electrical connections.

Checking atmospheric pressure compen-

sation

First of all, open the cover of the housing in

which the atmospheric breather facility

1)

is

located. The displayed measured value must

not change. If, however, the displayed value

changes, the compensation of the atmos-

pheric pressure does not function correctly

and the measured value will be distorted.

Therefore check:

- the breather facility on the housing

- the external connection housing

VEGADIS 12

- the capillaries in the special housing.

Note:

The same atmospheric pressure must be

acting on the breather facility and the open

vessel.

Checking electrical connections

Pressure

transmitter

terminals

~

1 2 3

+

-

Voltage

Current

Current

External

energy source

V

mA

mA

1)

It consists of a black plastic screwed insert with

integrated filter element.

Checking the voltage

- The terminal voltage on the pressure trans-

mitter must be at least 12 V DC.

- The terminal voltage on VEGADIS 12 must

be at least 12 V DC or 17 V DC (with dis-

play).

- The supply voltage for the pressure trans-

mitter through a VEGAMET signal condi-

tioning instrument must be approx.

18 V DC (on VBUS 25 V DC).

Checking the current

These values are only valid for pressure

transmitters with analogue signal transmis-

sion, not for pressure transmitters with digital

output signal (VBUS).

• Initial current with uncovered diaphragm of

the pressure transmitter: approx. 4 mA

(5 mA when operated on a VEGA signal

conditioning instrument)

• Measuring current during operation:

4 … 20 mA (5 … 19 mA when operated on

a VEGA signal conditioning instrument)

• Exceeding or falling short of the specified

measuring range: 20.5 mA or 3.8 mA

• Pressure transmitter defective or short-

circuit: current 22 mA or 3.6 mA

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