Yokogawa EJA530E Manual de usuario descargar pdf (Pagina 31)

<7. Operation>

7-3

IM 01C25F01-01E

Use a slotted screwdriver to turn the zero-

adjustment screw. Turn the screw clockwise

to increase the output or counterclockwise to

decrease the output. The zero point adjustment can

be made with a resolution of 0.01% of the setting

range. Since the degree of the zero adjustment

varies with the screw turning speed, turn the screw

slowly to make a ne adjustment and quickly to

make a rough adjustment.

(2) When you cannot obtain the Low Range

Value from the actual measured value of

0%;

Adjust the transmitter output to the actual measured

value obtained by a digital manometer or a glass

gauge.

[Example]

The measuring range of 50 to 250 kPa; the actual

measured value of 130 kPa.

130–50

250–50

Actual measured value=

x100=40.0%

(=10.4mA)

Turn the screw to match the output signal to the

actual measured value.

7.3 Starting Operation

After completing the zero point adjustment, follow

the procedures below to start operation. Steps

1) and 2) are specic to the differential pressure

transmitters.

1) Conrm the operating status. If the output

signal exhibits wide uctuations (hunting) due to

periodic variation in the process pressure, use

the communicator to dampen the transmitter

output signal. Conrm the hunting using a

receiving instrument or the integral indicator,

and set the optimum damping time constant.

2) After conrming the operating status, perform

the following.

IMPORTANT

• Remove the communicator from the terminal

box, and conrm that none of the terminal

screws are loose.

• Close the terminal box cover and the

amplier cover. Screw each cover in tightly

until it will not turn further.

• There are two covers that must be locked

on the ATEX Flameproof type transmitters.

An Allen head bolt (shrouding bolt) under

the edge of each cover is used to lock the

cover. When the shrouding bolt is driven

counterclockwise with an Allen wrench, the

bolt rotates upward and locks the cover. (See

section 8.4.) After locking the covers, conrm

that they are secure and cannot be opened

by hand.

Tighten the zero-adjustment cover mounting

screw to secure the cover.

• Tighten the zero-adjustment cover mounting

screw to secure the cover.

7.4 Shutting Down the

Transmitter

Shut down the transmitter as follows.

Steps 2) and 3) are specic to the differential

pressure transmitters.

1) Turn off the power.

2) Close the stop valve.

3) Open the equalizing valve.

4) Close the high pressure stop valve.

5) Close the tap valves.

NOTE

• Whenever shutting down the transmitter for a

long period, remove any process uid that is

in the transmitter pressure-detector section.

• The equalizing valve must be left OPEN.

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Yokogawa EJA530E Manual de usuario Pagina 31

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