Osram HQI-E 150 W/NDL CL Technical Information download pdf (Page 32)

3

2

7 Luminaire desi

g

n and plannin

g

o

f

li

g

htin

g

systems

7.1

M

easur

i

n

g

temperatures, am

bi

ent temperature

7.1.1

G

eneral physical conditions for temperature

li

m

i

ts

f

or outer

b

u

lb

s an

d

pi

nc

h

es

i

n meta

l

h

a

lid

e

l

am

ps

W

hen the limit values

f

or

p

inch tem

p

erature or outer

bulb temperature

f

or hard and so

f

t

g

lass are exceeded,

the

f

ollowing can be expected

:

• th

e

fo

il

o

xi

d

iz

es

•

t

h

e evacuate

d

outer tu

b

e co

ll

apses an

d

t

h

e

g

as-

f

illed outer tube blows out when the glass

t

u

rn

s

soft

•

t

h

e cement

i

n screw-

b

ase

l

amps crum

bl

e

s

A

lthou

g

h quartz

g

lass can withstand

f

ar hi

g

her temper

-

atures than the stated limit values, it is

p

ossible

f

or the

a

r

c

t

ube

t

o

o

v

e

rh

ea

t wh

e

n th

e

s

t

a

t

ed

limit v

a

l

ues

for

the outer bulb are exceeded, with the

f

ollowin

g

e

ff

ects

:

•

c

hange in colour propertie

s

•

l

ea

ki

n

g

arc tu

be

•

blackenin

g

o

f

the arc tube and deterioration in

l

u

min

ous

f

l

u

x m

a

int

e

n

a

n

ce

Th

e outer

b

u

lb

temperature

i

s on

ly

an

i

n

di

r

ect

i

n

di-

cator for arc tube load!

O

uter bulb and arc tube are

coup

l

e

d

by

ra

di

at

i

on an

d

to a sma

ll

extent

by

t

h

erma

l

co

n

duc

t

io

n v

ia

t

he

leads.

Whil

e

i

t

i

s

i

m

p

ortant to

li

m

i

t t

h

e outer

b

u

lb

tem

p

era

-

ture,

i

t

i

s wort

h

y to note t

h

at an

i

na

d

equate

l

y

d

es

ig

ne

d

r

ef

l

ec

t

o

r

ca

n

s

till

cause

th

e

a

r

c

t

ube

t

o

o

v

e

rh

ea

t with

-

out any ma

j

or c

h

an

g

e

i

n t

h

e outer

b

u

lb

temperature

(

see also chapter 7.9 “

O

ptical desi

g

n of reflectors”

).

O

ne indication that the desi

g

n of a luminaire is in

-

su

ff

icient comes

f

rom comparin

g

the lamp volta

g

e

measured when burnin

g

f

reely outside the luminaire,

and inside the luminaire a

f

ter bein

g

le

f

t lon

g

enou

g

h

to sta

bili

ze.

Th

e

i

ncrease

d

l

amp vo

l

ta

g

e measure

d

i

n

l

am

p

s

<

4

00

W

i

n t

he

lu

m

i

n

ai

r

e

should

n

o

t

e

x

ceed

5

V.

There is no notable di

ff

erence in the lamp volta

g

e

inside the luminaire

f

or lamps with watta

g

e input

>

1000 W, outer bulb and

f

ree-burnin

g

operation. But

soilin

g

o

f

the outer bulb caused by evaporation

f

rom

l

um

i

na

i

re components can cause t

h

e

l

amp vo

l

ta

g

e

o

v

e

r it

s

se

rvi

ce

lif

e

t

o

in

c

r

ease

m

o

r

e

th

a

n in fr

ee

-

bu

rn-

in

g

operation. This increase depends on the level o

f

sur

f

ace soilin

g

in the lamp and can there

f

ore not be

put in

f

i

g

ures. To avoid this e

ff

ect, it is recommended

to use tem

p

erature- an

d

UV

-res

i

stant mater

i

a

l

s

i

n t

h

e

l

u

min

a

ir

e.

7.1.

2

2

M

easurement w

i

t

h

t

h

ermocou

pl

e

M

easurement w

i

t

h

t

h

ermocoup

l

e

i

s a s

i

mp

l

e, pract

i

ca

l

m

ethod o

f

obtainin

g

measured values

.

Please adhere to the

f

ollowin

g

to properly measure

w

i

t

h

a t

h

ermocou

pl

e

:

•

G

ood contact with the surface bein

g

measured

• Low heat dissipation

f

rom the connection point

a

n

d

th

e

r

efo

r

e

– thermocou

p

le wire with a small diameter

– thermocouple wire parallel to the sur

f

ace bein

g

m

easu

r

ed

Foil

Outer bulb

Arc tube

Capillary

Radiation

Heat flow

Fi

g

. 33: Dia

g

ram to show thermal couplin

g

o

f

arc tube

a

n

d

ou

t

e

r

bulb

Fi

g

. 34: A

ff

ixin

g

the thermocouples to the outer bulb

a

n

d

t

h

e

l

amp

b

ase

Fi

g

. 35:

C

lampin

g

the thermocouple on the outer bulb

usin

g

a sprin

g

element

1 2 ... 27 28 29 30 31 32 33 34 35 36 37 ... 55 56

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