AIRFRAME ELECTRICAL SYSTEMS
TERMS QUESTIONS & ANSWERS
pole shoe - ANSWER The field assembly part of an electric generator or motor. Also
known as a field pole
interpole - ANSWER A field pole in a compound-wound electrical generator used to
correct for armature reaction.
three-unit regulator - ANSWER A voltage regulator used in some DC generator
systems. This type of regulator consists of three coils: current limiter, reverse current
cutout, and voltage regulator
growler - ANSWER Test equipment used to check generator and starter armatures for
shorts. The growler formes the primary of a transformer and the armature forms the
secondary. Shorts show up since they cause vibration in a thin piece of metal, such as
hacksaw blade, held over the armature
alternator control unit - ANSWER A device in aircraft with DC alternator systems that
receives inputs from the alternator and provides a stable voltage and current supply to
the aircraft electrical bus. The ACU also provides voltage and current regulation as well
as over-and undervoltage sensing and protection.
ACU's protect the systen from alternator over voltage condition by either momentatrily
or permanatly removing the alternator from the circuit
constant-speed drive unit - ANSWER A hydraulic transmission that can be controlled
either by electricity or mechanically. Constant speed drives are used with alternators
and enable the alternator to produce the same frequency regardless of the engine's
speed, from idle to maximum speed.
CSD - ANSWER Constant Speed Drive Unit
internal resistance - ANSWER The resistance of the battery to the flow of current. It
causes a voltage drop proportional to the amount of current flow
capacity - ANSWER The ability of a battery to produce a given amount of current for a
specified time. Capacity is expressed in ampere-hours
ampere-hour - ANSWER A measure or rating of a battery that indicates the capacity of
electrical energy the battery can supply. One ampere-hour is the product of current flow
in amperes, multiplied by the length of time, in hours, that the battery can supply this
current.
, five-hour discharge rating - ANSWER The ampere hour rating of a battery that will
discharge the battery in five hours. This is the most commonly used rating for aircraft
batteries
constant voltage - ANSWER A method of providing charging voltage to the battery
throughthe generating system in an aircraft. The constant voltage method utilizes a
voltage that is slightly higher (14 volts) than the battery charged (12 volts)
nickel-cadmium battery - ANSWER A battery made up of alkaline secondary cells. The
positive plates are nickel hydroxide, the negative plates are cadmium hydroxide, and
potassium hydroxide is used as the electrolyte
thermal runaway - ANSWER A condition existing in a nickel cadmium battery when the
cell resistances become unbalanced because of temperature. The resistance of some
cells decreases and allows the cells to take more current, which lowers their
resistanceeve further and creates more current. This action continues until the battery is
seriously damaged, sometimes exploding.
deep-cycling - ANSWER A treatment of nickel cadmium batteries in which the battery is
completly discharged, the cells shorted out and allowed to "rest." The battery is then
recharged to 140% of its ampere-hour capacity.
bus tie breaker - ANSWER A device in an aircraft electrical system that permits the
electrical load from a failed generator to be reconnected to the bus of an operating
generator.
BTB - ANSWER Bus Tie Breaker
in aircraft electrical equipment. These sensative components are labeled with the ESDS
emblem to alert the technician of this potential hazard.
ESDS - ANSWER Electro Static Discharge Sensative
ACU - ANSWER Alternator Control Unit
armature reaction - ANSWER the distortion of the gnerator field flux by the current
flowing in the windings of the armature
Magnesyn System - ANSWER An AC remote indicating system in which a permanent
magnet is used as the rotor.
oscillator - ANSWER an electronic device that converts DC into AC. An electronic circuit
that produces AC with frequencies determined by the inductance and capacitance in the
circuit.
TERMS QUESTIONS & ANSWERS
pole shoe - ANSWER The field assembly part of an electric generator or motor. Also
known as a field pole
interpole - ANSWER A field pole in a compound-wound electrical generator used to
correct for armature reaction.
three-unit regulator - ANSWER A voltage regulator used in some DC generator
systems. This type of regulator consists of three coils: current limiter, reverse current
cutout, and voltage regulator
growler - ANSWER Test equipment used to check generator and starter armatures for
shorts. The growler formes the primary of a transformer and the armature forms the
secondary. Shorts show up since they cause vibration in a thin piece of metal, such as
hacksaw blade, held over the armature
alternator control unit - ANSWER A device in aircraft with DC alternator systems that
receives inputs from the alternator and provides a stable voltage and current supply to
the aircraft electrical bus. The ACU also provides voltage and current regulation as well
as over-and undervoltage sensing and protection.
ACU's protect the systen from alternator over voltage condition by either momentatrily
or permanatly removing the alternator from the circuit
constant-speed drive unit - ANSWER A hydraulic transmission that can be controlled
either by electricity or mechanically. Constant speed drives are used with alternators
and enable the alternator to produce the same frequency regardless of the engine's
speed, from idle to maximum speed.
CSD - ANSWER Constant Speed Drive Unit
internal resistance - ANSWER The resistance of the battery to the flow of current. It
causes a voltage drop proportional to the amount of current flow
capacity - ANSWER The ability of a battery to produce a given amount of current for a
specified time. Capacity is expressed in ampere-hours
ampere-hour - ANSWER A measure or rating of a battery that indicates the capacity of
electrical energy the battery can supply. One ampere-hour is the product of current flow
in amperes, multiplied by the length of time, in hours, that the battery can supply this
current.
, five-hour discharge rating - ANSWER The ampere hour rating of a battery that will
discharge the battery in five hours. This is the most commonly used rating for aircraft
batteries
constant voltage - ANSWER A method of providing charging voltage to the battery
throughthe generating system in an aircraft. The constant voltage method utilizes a
voltage that is slightly higher (14 volts) than the battery charged (12 volts)
nickel-cadmium battery - ANSWER A battery made up of alkaline secondary cells. The
positive plates are nickel hydroxide, the negative plates are cadmium hydroxide, and
potassium hydroxide is used as the electrolyte
thermal runaway - ANSWER A condition existing in a nickel cadmium battery when the
cell resistances become unbalanced because of temperature. The resistance of some
cells decreases and allows the cells to take more current, which lowers their
resistanceeve further and creates more current. This action continues until the battery is
seriously damaged, sometimes exploding.
deep-cycling - ANSWER A treatment of nickel cadmium batteries in which the battery is
completly discharged, the cells shorted out and allowed to "rest." The battery is then
recharged to 140% of its ampere-hour capacity.
bus tie breaker - ANSWER A device in an aircraft electrical system that permits the
electrical load from a failed generator to be reconnected to the bus of an operating
generator.
BTB - ANSWER Bus Tie Breaker
in aircraft electrical equipment. These sensative components are labeled with the ESDS
emblem to alert the technician of this potential hazard.
ESDS - ANSWER Electro Static Discharge Sensative
ACU - ANSWER Alternator Control Unit
armature reaction - ANSWER the distortion of the gnerator field flux by the current
flowing in the windings of the armature
Magnesyn System - ANSWER An AC remote indicating system in which a permanent
magnet is used as the rotor.
oscillator - ANSWER an electronic device that converts DC into AC. An electronic circuit
that produces AC with frequencies determined by the inductance and capacitance in the
circuit.
