Eli5 How does a rapid start fluorescent light ballast work.

Question

I understand how a preheat, instant start and programmed start work. But how does the ballast put high starting voltage and low heating voltage at the same time

In: 2

Answer 1

[An image is handy here](https://www.electrical101.com/wpimages/1lamp-series-ballast-wiring-diagram.webp), and some of this is for people who don’t know how a fluorescent tube works

There are “filaments” on each end of the bulb that are connected through the two pins, but the main power of the bulb flows between the two ends and through the ionized gas in the tube

The heating voltage is between the two blue wires and the two red wires in the image and only heats the filament on their respective ends of the bulb.

The starting voltage is from blue to red and ionizes the gas in the middle

If from top to bottom you set Blue 1 to +301 volts, blue 2 to +299V, red 1 to -299V, and red 2 to -301 volts then you get 2 volts across each of the filaments (low heating voltage) and 600V across the tube (high starting voltage)