Daewoo DVN-8100N Instruction Manual download pdf (Page 8)

The

pitch

feedback

potentiometer

and its

driving

sprocket

gear

are

contained

in the

feedback

unit,

which

is

mounted

on the

motor stand

and is

connected

to the

pitch position indicator

rod

which

protrudes

from

the

gear housing

flange.

The

control

and

feedback

potentiometer

from

a

balanced

sprit

phase

closed

loop,

feeding

a

high

gain

amplifier

and

phase detecting network.

Movement

of the

control potentiometer

presents

an

error

signal

at the

amplifier

input,

this

signal

is

amplified

and

operates

the

phase detecting network which feeds

a

control signal

to the

solenoid

valve, directing

the oil to the

correct

side

of the

servomotor

cylinder(cross head) which

controls

the

pitch

of the

propeller blades.

The

electrical balance

is

restored

by the

corresponding movement

on the

feedback

potentiometer.

The

system

gives

fine

control

of the

pitch setting,

and any

deviation caused

by

external

forces

is

automatically corrected.

In

addition, this control system provided automatic load control

(ALC)

system which

consists

of

PI

control, load setting

function

and

electric

current signal.

The

electric current signal

is

supplied

from

the CT

located

at

starter

panel.

It has

function that

the

blade angle

is

automatically

reduced

to

protect

the

main motor overload.

The

reducing action

is

achieved when

the

current signal

is

reached

to the

preset

level which

corresponds

to the

rated load

of

motor.

The

action

is

automatically

reset

when

the

load

is

decreased.

5.7

Pitch

to

zero system

During

voyage

of the

vessel, sometimes

the

propeller

is

rotated

by the

tide

( the

seawater

coming

into

the

thruster

tunnel

) and the

pitch

is

moved

out of the

zero

position.

In

this

situation,

the

hydraulic pump automatically will

be

started

and the

pitch

is

kept

in

zero.

When

blade angle

returns

to

zero

position, hydraulic pump

and

solenoid valve will

be

stopped

after

preset

time.

This

mode

is

operated independently

from

normal mode

by

pushing

of

this mode

select

button

on

W/H

control panel.

Other unrelated lamps except followings shall

not be

caused under zero pitch mode.

1)

Ind. lamp

of

zero pitch mode

2)

Ind. lamp

of

blade neutral

3)

Ind. lamp

of

hyd. pump

run

4)

Ind. lamp

of

acting solenoid valve

5)

Alarm lamps

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