DEFINITIONS - CONT - TM-55-1905-223-24-40313

TM 55-1905-223-24-4

GLOSSARY - CONT

DEFINITIONS - CONT

POLARITY

An electrical term which indicates the direction in which current flows in

a conductor. In a direct current system, current constantly flows in the

same direction. In an alternating current system, current changes

direction as the polarity of the ac voltage source changes.

RECTIFIER

A device used to convert alternating current to direct current. A diode is

one of several devices which act as rectifiers.

An electromechanical device having a magnetic coil which, when

energized, opens or closes several sets of contacts.

Opposition to the flow of current.

RESISTOR

A component which possesses resistance.

RHEOSTAL

A variable resistor.

ROTOR

The rotating part of a generator.

SCALE

Insoluble materials that settle out of cooling water and adhere to the

metallic surfaces; buildup of hard materials which interfere with the

transfer of heat.

An electromechanical device which, when energized, acts on a movable

core or plunger in the center of the energizing coil to perform

mechanical work.

STABILITY

A condition which describes engines governor and generator voltage

regulator. These systems provide frequency and voltage stability if they

can maintain or quickly re-establish steady- state, regulation after a load

change,

STATOR

The stationary part of a generator or exciter.

SURGE SUPPRESSOR

A device capable of conducting current in either direction in the

presence of high transient voltages, thus protecting devices that could

otherwise be damaged.

VARISTOR

A surge suppressor.

Glossary 6