Indoor Furnishings User Manual

18
2000-11-07
Cold ignition requires a higher ignition voltage.The minimum
required ignition voltage can be found in the table below. It is
advisable that the lamp current directly after ignition is at least
equal to the nominal lamp current.This reduces the time that the
lamp is burning with a cold cathode thus the damage to the coil.
Minimum required ignition voltage for cold ignition:
Lamp Minimum Lamp Minimum
type voltage type voltage
‘TL’5 HE V ‘TL’5 HO V
14W 560 24W 560
21W 600 39W 600
28W 650 49W 800
35W 800 54W 800
80W 800
4.1.4 Fast re-ignition
Normal ignition is specified for -15 °C< T
amb
< 60 °C. In this
condition the cold spot temperature,and so the temperature of
the mercury during ignition,are both at T
ambient
:T
Hg
= T
amb
.
During operation of the lamp T
ambient
will increase.Furtheron the
mercury temperature (T
cold spot
) is about 10 °C higher than
T
ambient
.
So T
Hg
= T
amb
+ ~ 10 °C.
So for fast re-ignition after a period of operation also a higher
V
ignition
related with t his higher mercury temperature must be
applied.If the lamp is operated at very high ambient temperatures
(T
amb
> 60 °C) with fast re-ignition the mercury temperature
might be higher than the maximum specified in the previous table.
In these circumstances fast re-ignition within the range of V
ign
is
not guaranteed.Here either an increased V
ignition
or waiting a
short time,until T
cold spot
has been decreased,are the alternatives.
4.2 Dimming
Dimming can be defined as the reduction of the luminous flux of a
lamp,either continuously or in steps,by reducing the operating
current.
For ensuring the proper operation of ‘TL’5 lamps in dimming condi-
tions,the conditions described in the following two sections should
be fulfilled.
Please note that fluorescent lamps when dimmed will experience a
colour shift.
4.2.1 Electrical properties of the discharge
Dimming is done by reducing the discharge current flowing through
the lamp.At lower lamp currents,the lamp voltage will increase
(see section 3.4 for the relationship between lamp voltage and
current at 35 °C ambient temperature).The lamp voltage is not
only dependent on the lamp current,but also on the mercury
vapour pressure in the lamp.Under equilibrium conditions the
mercury vapour pressure is controlled by the temperature of the
coldest spot inside the lamp.Therefore the values of lamp voltage
and light output also depend on the temperature of the air imme-
diately surrounding the lamp and also on the burning position of
the lamp (see section 2.5).Under High Frequency conditions with
sinusoidal discharge current,the lamp voltage will be sinusoidal as
well.The lamp power can thus be estimated with considerable
accuracy using the product of lamp current and lamp voltage.