ballast

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

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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.

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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.

4. Same as constant-wattage ballast.