ballast

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ballast

1. any dense heavy material, such as lead or iron pigs, used to stabilize a vessel, esp one that is not carrying cargo
2. crushed rock, broken stone, etc., used for the foundation of a road or railway track
3. Electronics a device for maintaining the current in a circuit

Ballast

Power-regulating device that modifies input voltage and controls current to provide the electrical conditions necessary to start and operate gaseous discharge lamps, especially fluorescents and HID (high-intensity discharge) lamps.

ballast

[′bal·əst]
(aerospace engineering)
A relatively dense substance that is placed in the cab of a balloon and can be thrown out to reduce the load or can be shifted to change the center of gravity.
(civil engineering)
Crushed stone used in a railroad bed to support the ties, hold the track in line, and help drainage.
(electricity)
A circuit element that serves to limit an electric current or to provide a starting voltage, as in certain types of lamps, such as in fluorescent ceiling fixtures.
(materials)
Coarse gravel used as an ingredient in concrete.
(naval architecture)
A relatively heavy material such as lead, iron, or water placed in a ship to ensure stability or to maintain the proper draft or trim.
To pump seawater into empty fuel tanks of a ship to ensure its stability or suitable draft and trim for seaworthiness.

ballast

1. Coarse stone, gravel, slag, etc., used as an underlayer for poured concrete.
2. A device used to provide the required starting voltage and operating current for fluorescent, mercury, or other electric-discharge lamps.
3. Class P: A ballast for a fluorescent lamp which meets the requirements of the Underwriters’ Laboratories, Inc.; includes an automatic resetting thermal protector to remove the ballast from the circuit if its temperature exceeds a specified value.

ballast

Weight installed in an airplane to ensure that the center of gravity is always within the permissible limits. In some aircraft, fuel is used as a ballast. This fuel, however, cannot be burned by the aircraft.