Vorschalt

Vorschalt is the German shorthand for Vorschaltgerät, a device used in electrical lighting circuits to manage gas-discharge lamps such as fluorescent and high-intensity discharge (HID) lamps. The Vorschaltgerät provides ignition voltage and current regulation, protecting both the lamp and the power supply during operation.

During startup, the Vorschaltgerät supplies a high transient voltage to strike the arc, then limits current to the lamp's rated level once the arc is established. In older systems this function was complemented by a separate starter; modern designs often integrate the starting and current-regulating functions in a single unit.

Vorschaltgeräte come in two main types: electromagnetic (inductive) ballasts and electronic ballasts. Electromagnetic ballasts use inductance to limit current and typically operate at mains frequency, producing noticeable flicker and heavier hardware. Electronic ballasts switch at high frequency, are more compact and efficient, reduce flicker, and often include improved power-factor and dimming capabilities.

Applications and relevance: Ballasts are standard in commercial and institutional lighting installations using fluorescent or HID lamps. Energy efficiency regulations and advances in lighting technology have driven a shift from magnetic to electronic ballasts in new installations, while older systems may still employ electromagnetic units. The term Vorschalt is mainly used in German-speaking contexts; in English-language literature the term ballast is common, with subtypes magnetic and electronic.