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.
References in periodicals archive ?
Momoya, "Numerical method for evaluating the lateral resistance of sleepers in ballasted tracks," Soils and Foundations, vol.
Different weightings of ballasted roofs were compared to a paver system and black and white membranes.
Continuous monitoring of temperatures, heat flows, and weather conditions, as well as periodic verification of the surface properties of solar reflectance and thermal emittance, provided data to determine what impact a ballasted roof has on heat flow into a building and on roof-surface temperature.