Philips Electromagnetic Lamp manual 151, Fault finding Fault IV lamp flickers, Electrical tests

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3.19 Fault finding

Fault IV: lamp flickers.

• Possible cause:

-lamp operating voltage too high, end of lamp life,

-low supply voltage, check ballast connection,

-burning position out of specification.

Fault V: strong blackening of lamp, light output reduction.

• Possible cause:

-overload operation,

-wiring / ballast defect,

-capacitor across lamp instead of mains,

-end of lamp life.

Fault VI: fuse acting shortly after switch-on.

• Possible cause:

-fuse rating too low or not slow-acting type,

-wiring defect, overload operation.

Fault VII: colour differences in lamp colour.

• Possible cause:

-strongly varying burning positions in an installation,

-underload,

-lamps of different operating age or different suppliers,

-lamps of different colours used.

4: Electrical tests

Voltage and current measurements present the possibility of exposure to hazardous voltages and should be performed only by qualified personnel.To measure the correct effective values, true RMS voltmeters have to be used. Measurements with non-true RMS meters can give up to 50 per cent lower values, especially during measurements of the lamp voltage or other non-sine-wave voltages (see table below).

Description	Waveform	True RMS	Peak RMS	Average RMS
			calibrated	calibrated
Sine wave		100	100	100
Square wave		100	71	111
Triangular wave		100	120	96
Single-phase
electronic load		100	200	50
current
Single-phase
electronic plus		100	166	83
30 % linear load

The parallel compensating capacitor can be measured in two ways:

1)Measure mains current and lamp current.

If both are the same, the capacitor is open-circuit and has to be replaced.

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