Standard conventional and circular fluorescent lamps with filaments can be ignited easily and much more quickly by using Thyristors instead of the mechanical starter switch, and solid state Thyristors are more reliable.
Thyristors produce a pure solid state igniting circuit with no mechanical parts in the fluorescent lamp fixture. Also, because the lamp ignites much faster, the life of the fluorescent lamp can be increased since the filaments are activated for less time during the ignition. The Thyristor ignition eliminates any audible noise or flashing off and on which most mechanical starters possess.
Figure shows a circuit for igniting a fluorescent lamp with 240 V line voltage input using Triac and DIAC networks.
Figure illustrates a schematic using a SIDAC phase control network to ignite a 240 V ac fluorescent lamp. The one major change is that two K2400E devices in series are used to accomplish high firing voltage for a fluorescent lamp.
Source: Littelfuse