Flowserve PMV D3 Digital Positioner Manual de usuario descargar pdf (Pagina 7)

7

5. Function

Control signal 4 - 20 mA

Potentiometer

Piezo-valve 1

Piezo-valve 2

Diaphragm

Pressure

regulator

Replaceable

Filter

Air supply 2 - 6 bar

1.2 bar

Venting

Venting

H

G

Double action function

The control signal and the feedback

potentiometer position are converted to di-

gital signals that are processed with a PID

algorithm in the microprocessor. This prov-

ides control signals to the two piezo-valves.

The two piezo-valves are closed in the

schematic diagram above and have no effect

on the valves A and D. Air from the pressure

regulator is lead through the open valve A to

the valve B, which opens. The supply

pressure can now pass through valve B to

the actuator via H. The actuator then moves

in the direction of the arrow. At the same

Signal converter

and

microprocessor

A

B

C

D

E

F

➾

time, air from valve A keeps valve C open

and allows venting of the actuator.

When both the piezo-valves open, valve

A closes but valve D opens and controls

valves E and F to that the actuator moves in

a direction opposite to the arrow. When only

piezo-valve 1 is open, the actuator is

stationary.

Single action function

Valve B is used for the supply air and

valve F for venting.

C– C+

Actuator

1 2 3 4 5 6 7 8 9 10 11 12 ... 59 60

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