Philips Electromagnetic Lamp manual 132, Electromagnetic interference

5 3.10 Electromagnetic interference

Fig. 126 shows an example of a delta filter used for suppressing radio interference.The apex of the filter must be connected to the ground. More complicated filters are used in three-phase networks.

Avoid earth looping (all earth terminals to one point) and create maximum distance between audio and lighting cabling. If audio and lighting cables have to cross each other, it should be done in a perpendicular way. In sensitive applications screening of cabling is necessary.

Fig. 126. Delta filter used for suppressing radio interference.

L

5 nF

0.2 mF

5 nF

N

3 11 Lifetime

When used within the specifications, the various circuit components will last for many years with no more failures than approx. 1 per cent per year (except lamps and glow-switch starters).

Most of the time, failures in the gear components are caused by external circumstances, such as wrong wiring or connections, short- circuiting, extreme heat or humidity, mains voltage peaks, poor maintenance and the like.

For example, capacitors for lighting installations with the VDE approval according to VDE 0560 must achieve a lifetime of 30 000 hours at their marked voltage (250 or 450 V) and their maximum case temperature

(85 or 100 ºC). Higher voltages will shorten the capacitor life as follows:

Voltage	1.15	1.25	1.30	1.35	1.40	1.45	1.50
(times Vmark)
Lifetime (h)	8500	4000	2900	2000	1500	1100	780

A failure rate of 5 per cent is then accepted and the capacitance loss must be less than 10 per cent for parallel and 5 per cent for series capacitors. Temperatures above the marked maximum capacitor case temperature will halve the lifetime of the capacitor for every 8 degrees increase.

Therefore, if there are too many failures with capacitors, the capacitors may be too hot or the applied voltage is (temporarily) too high.

For glow-switch starters the number of switches is specified as 10 000 or more. Deviations are caused by the different starting currents of the various lamp types.

For electronic starters, the most relevant factor is the allowed ambient temperature or the maximum case temperature tc.

The specified temperature range is from -40 ºC till + 80 ºC. Exceeding these temperature limits will shorten the lifetime dramatically.

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