Fluorescent lamp
T8 40 W fluorescent tube on a magnetic ballast (1.2 H choke) with a glow starter · 220 V 60 Hz · the starter heats the filaments, then opens: the choke’s kick strikes the tube, and the choke then limits the current · lagging power factor about 0.5 without a correction capacitor
Try it on the benchThe lab drops it on an empty bench and opens its datasheet card.
Typical part: T8 40 W tube, magnetic ballast and FS-4 starter
Pins
- L
- N
Ratings and limits
| Tube | 40 W, ≈ 100 V arc |
|---|---|
| Ballast | ≈ 1.2 H, 220 V 60 Hz |
| Power factor | ≈ 0.5 lagging (add 4.5 µF to correct) |
How to use it
The ballast is just a big inductor: it makes the voltage kick that strikes the tube and then limits its current. Flicker at 120 Hz and a lagging current are why they were replaced by electronic ballasts and LED tubes.