1. general. Weights placed at the bottom of a top-heavy object to keep it upright, i.e. a sailing ship's ballast.
2. Lighting. Power
supply for an arc or gaseous discharge
light source, containing a transformer
, inductor, and voltage
and current-regulating circuitry. On moving lights, the ballast is inside the upper enclosure; on most followspots and HMI
movie lights, the ballast is an external box, connected to the fixture
via an umbilical or head cable
. More modern ballasts use switch-mode electronic power
supplies rather than inductors to regulate voltage
to the lamp source.
View attachment 4194
Ballast is shown on the ground
next to the four-legged, castered stand.
3. Rigging. Weight added to a pipe (a.k.a. line-set, baton
#) to compensate for weight being removed; I.e. scenery, lights, speakers or other items. (See Counter Weight Rigging)