BRUEL & KJAER 4915 - Operation as a Free-Running Stroboscope; Determination of Motion Frequency or Speed

BRUEL & KJAER 4915

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Mains Voltage Setting

The 4913

may

be

powered

from

100, 115, 127, 200, 220 and 240 V ± 10% (50

to

60 Hz)

single

phase

AC

mains

lines.

To

select

the

correct

mains

voltage

setting,

use a small

coin

or

wide-blade

screwdriver

to

turn

the MAINS

VOLT

AGE

selector

on the

rear

panel so

that

the

appropriate

voltage

setting

on the

selector

lines

up

with

the

black

arrow

printed

on

the

panel.

Fuse Rating

The

mains

fuse

is

contained

in the fuse

holder

immediately

above

the

MAINS INPUT on

the

rear

panel and

may

be released using a

screwdriver

to

turn

the

centre

of

the

holder.

For

operation

from

100

to

127 V

supplies

the fuse

should

be a 1 A

slow

blow

(B & K no.

VF 0013),

whilst

for

200

to

240 V

supplies

it

should

be

an 0,5 A

slow

blow

(B & K no.

VF 0023).

Make

sure

that

only

fuses

of

the

required

rated

current

and

of

specified

type

are

used

for

replacement.

The use

of

mended

fuses

or

short

circuiting

of

the

fuse

holder

is

prohibited.

Supply Connections

Once

the

mains

voltage

setting

and fuse have been

checked,

the

mains

supply

may

be

connected

to

the

MAINS

INPUT

of

the 4913 using

the

Power

Cable

AN 0020 supplied. The

4913 has a

high

standard

of

safety

insulation

in

accordance

with

safety

class

II

of

IEC 348

and

therefore

its

chassis

need

not

be

connected

to

mains

ground.

3.2. OPERATION AS A "FREE RUNNING" STROBOSCOPE

For

use

of

the 4913 as a

"free-running"

stroboscope,

its

internal

generator

is

employed.

This

type

of

operation

is well

suited

for

quick

investigation,

fault

detection

and

measure-

ments

on

rotating

and

reciprocating

machines

operating

at

a

relatively

constant

frequency.

3.2.1. Determination of Motion Frequency or Speed

For

obtaining

a

stationary

stroboscopic

image

of

a

rotating

or

reciprocating

machine,

plus

determination

of

its

motion

frequency,

the

basic

operating

procedure

is as follows:

1.

Carry

out

the

preliminary

checks

and

adjustments

necessary

(see

section

3.1) and

connect

the

drive

cable

plug

of

the

Lamp

Unit

to

the

LAMP

OUTPUT

socket

of

the

4913.

2.

Set

the

front

panel

controls

of

the 4913 as

follows:

DISPLAY SELECTOR:

TRIGGER SOURCE:

FUNCTION SELECTOR:

DELAY:

SLOW

MOTION:

Trigger

Freq.

"Hz"

or

"r/min"

"Int.

Gen."

"Phase

Delay"

extreme

anticlockwise

position

extreme

anticlockwise

position

11

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