Instruction manual

64
Solving this problem with an appropriate housing design and/or type of
installation for the luminaire (forced cooling, increased convection effect)
has a further advantage in reducing the interference noise level and should
therefore seriously considered.
Experiments have shown that the amount of noise generated is closely
linked to the operating temperature of the electronic control gear. This is a
particularly important factor if the unit has been installed in accordance with
the recommendations given above. In extreme cases, it will not be possible
to work without additional heat sink.
In addition, the noise level increases disproportionately as the temperature
of the ECG rises. It is therefore best to operate the control gear at a
temperature below the maximum recommended value. In practice, this
means that the amount of noise generated is less, the lower the measuring
point temperature tc. A combination of acoustic insulation of the ECG and
reduced operating temperature represents the best technical solution.
In general, the following applies:
Electronic control gear for T5/∅ 16 mm-fluorescent lamps FH
®
...HE and
FQ
®
...HO are so quiet that even in very quiet surroundings they cannot be
discerned by the human ear. They are therefore ideal for sound-sensitive
areas such as radio studios with CD quality recordings. If necessary,
random samples should be used to determine whether, given the local
parameters (volume of the studio, reverberation time and number of
ECGs), insulation as described above is needed from an acoustic point of
view or whether standard products could be used.
6.3 Treatment Rooms,
Operating Rooms
In rooms used for medical treatment electrodes may be placed on a
patient’s body to obtain electro-cardiogram or electro-encephalogram
recordings. To eliminate interference from magnetic fields, DIN VDE 0107
defines the maximum recommended inductance strengths. Luminaires
fitted with QUICKTRONIC
®
control gear easily fall within this limit values at
distances of 0.75 m and greater.
Because of their magnetic field strengths, conventional control gear that
cannot be used for T5/
∅ 16 mm-fluorescent lamps but for T8/∅ 26 mm
tubes are often not suitable and have to be placed at least 3 m away.
6.3.1 Electromagnetic
Interference
Fluorescent lamps are not point light sources and cannot be adequately
focused, which means they are not considered suitable to light operating
tables. Dichroic halogen lamps are used almost exclusively. But even the
room lighting has to meet very stringent requirements in terms of radiated
magnetic fields. Sensitive patient monitoring systems in the operating room
and intensive care wards must not be exposed to leakage magnetic fields.
It is necessary to comply with the maximum recommended interference
levels and minimum installation distances for luminaires as defined in VDE
0107/6.81. Important information on this subject can be found in
Section
3.2
, electromagnetic compatibility.
Whereas conventional control gear had to be installed separately from the
luminaire in a central switch cabinet far enough away from the treatment
area, ECGs for T5/
∅ 16 mm fluorescent lamps can, in most cases, be
installed directly in the luminaire without any problem. The actual