5
3.5 Series connection of lamps
Parallel connection of two lamps on a common ballast is impossible because of the negative characteristic of the fluorescent lamp.All the current would flow through the lamp with the lower arc voltage.
Moreover, once the first lamp is ignited the lamp voltage is too low for the ignitor of the second lamp to ignite this lamp.
3 
6 
Neutral interruption and resonance
Normally each lamp circuit has its own compensating capacitor. In this way every luminaire can be switched separately without influencing the power factor. For the same reason lamp circuits based on
In the
A good neutral is essential.
Moreover, when the neutral is interrupted and the loads on the phases are not completely balanced ( i.e. the same wattage), then the voltage across the smallest load will increase and much more power will be consumed by that load.This will surely damage lamps and/or ballasts (see Fig. 119).
Suppose there are five loads of 1000 Ω , one connected between L1 and neutral and four connected between L2 and neutral.The current from L1 will be 230/1000 = 0.23 A and the power in the load will be 230 . 0.23 = 53 W.
The current from L2 will be four times higher (0.92 A) and the power too: 212 W.
If the neutral is interrupted, the
Fig. 118. Compensation in a phase/neutral network.
L1 | B |
|
L2
B
L3
B
1 2 3
La La La
C3 C2 C1
N
124
