Specific Application of The Alternators

Where is an alternator located?

In a gasoline- or diesel-powered vehicle, the charging system consists of three main components: the battery, voltage regulator, and alternator. The alternator works with the battery to generate electricity for the vehicle's electrical components. The alternator is usually located near the front of the engine and is driven by the crankshaft, which converts the up and down motion of the pistons into circular motion. Some early models used a separate drive belt from the crankshaft pulley to the alternator pulley, but most cars today have a single serpentine drive belt, or one drive belt that drives all components that rely on power from the crankshaft.

Specific application of the alternators

Alternators are widely used, the following are specific examples of alternator application.

Automotive alternators

Alternators are used in modern internal combustion engine vehicles to charge the battery and power the electrical system while the engine is running. Until the 1960s, cars used DC generators with commutators. With the availability of affordable silicon diode rectifiers, alternators are used.

Marine alternators

Marine alternators used on yachts are properly adapted to the seawater environment. They are designed to be explosion proof (ignition protected), so brush sparks cannot ignite explosive gas mixtures in the engine room environment. Depending on the type of system installed, they may be 12 or 24 volts. Larger marine diesels may have two or more alternators to handle the high power demands of modern yachts.

In a single alternator circuit, power can be split between the engine starting battery and the home or household battery (or batteries) by means of split charging diodes (battery isolators) or voltage sensitive relays. Due to the high cost of large household battery packs, marine alternators typically use external regulators. A multi-step regulator controls the electric field current to maximize charging efficiency (charging time) and battery life. Multi-step regulators can be programmed for different battery types. Two temperature sensors can be added, one for the battery to regulate the charging voltage and the other for an over-temperature sensor on the actual alternator to prevent the generator from overheating.

Diesel-electric locomotive alternator

In later diesel-electric locomotives and diesel-electric multiple units, the prime mover turns an alternator that supplies power to the traction motors (AC or DC). Traction alternators typically use integrated silicon diode rectifiers to provide up to 1200 volts DC to the traction motor. The first diesel-electric locomotives, many of which are still in use, used DC generators, before silicon power electronics made it easier to control the speed of DC traction motors. Most of these have two generators, one of which generates the field current for the larger main generator.

Radio alternator

Variable reluctance type high frequency alternators are commercially used for radio transmission in low frequency radio bands. They were used to transmit Morse code and were used experimentally to transmit sound and music. In an Alexandria alternator, both the field and armature windings are stationary and current is generated in the armature due to the changing reluctance of the rotor (which has no windings or current carrying parts). Such machines were used to generate radio frequency electrical current, albeit inefficiently, for radio transmission.