Sharp QT-80W Instruction Manual download pdf (Page 64)

control gear. Therefore, a direct comparison with conventional control gear

(chokes) does not make sense.

In T5 luminaires, the electronic control gear functions as a vibration source

and is capable of exciting adjacent metallic or plastic components so that

they act as resonators, amplifying the actual noise considerably and help to

spread it out.

To avoid this, especially the recommended minimum distance between two

T5/

∅ 16 mm- fluorescent lamps has to be respected so that no noise can

be generated due to physical contact.

1. For high luminaire efficiency the distance should be at least 48 mm

between the two lamps (approximately two fingers should fit

between the lamps)

2. When designing the luminaire for minimum distance the maximum

recommended base temperature of 120 °C may never be

exceeded.

6.2.2 Recommended

minimum distance

between lamp and

refelctor

The maximum recommended base temperature of 120 °C may never be

exceeded.

A distance of less than 3 mm between lamp and reflector can result in

generation of noise even in luminaires with non-dimmable ECGs.

At a distance of less than 6 mm between lamp and reflector the leakage

current of the dimmed lamps 35 W, 49 W and 80 W causes visible

differences in brightness between the ends of the lamps. In addition, the

radio interference suppression is getting worse.

OSRAM recommendation:

In general, OSRAM recommends to keep a minimum distance of

6 mm

between lamp and reflector. In certain cases (unfavourable capacitive

interference) the minimum distance should be even greater.

To develop luminaires that are as quiet as possible, it is therefore essential

to insulate the control gear and chassis or luminaire support. In other

words, there should be clearance below the ECG with the ECG mounted on

point supports on the luminaire chassis or on rubber absorbers as used for

conventional ballasts. Under certain circumstances, this type of mounting

may, however, lead to thermal problems since the best way to dissipate the

power loss to the environment is to have the ECG in full contact with the

chassis.

32 mm

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Sharp QT-80W Instruction Manual Page 64