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EGSA Definitions Exam Questions And Correct Answers
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EGSA Definitions ExamQuestions And Correct Answers
accuracy - Answer The comparison of an indicated value to a known reference value.
The quality of accuracy is often expressed by stating the difference between the two
values as a percentage of the known reference value.
A/D converter - Answer A device that converts an analog signal such as generator
output voltage into a digital "word" for use by a microprocessor.
aeration - Answer The entrainment of gas (air and/or combustion gas) in the coolant.
aftercooling - Answer Process by which the combustion chargeair exiting from the final
stage of compression is cooled by means of an air to air, or liquid to air, heat exchanger,
before introduction into the engine.
air bleed - Answer Pressurized air extracted from the gas turbine engine compressor.
air cleaner - Answer Device to filter combustion air at the entrance to the combustion air
circuit.
air cooled engine - Answer An engine that is cooled by means of air being forced about
the heated parts of the engine.
air gap - Answer A separating space between two parts of magnetic material through
which the magnetic flux must pass. A typical representation of this space is the
clearance between the rotor and stator of an electrical machine.
air intake silencer - Answer Device to reduce the noise of incoming combustion air and
objectionable noise originating in the intake manifold.
air restrict indicator - Answer A device applied in conjunction with a dry-type air cleaner
to signal the necessary maintenance of the filter cartridge as determined by an
increased restriction to air flow.
air/gas starting - Answer Utilizing compressed air or gas for engine or turbine cranking.
alternating current (ac) - Answer A current which reverses in regularly recurring
intervals of time and which has alternately positive and negative values, and occurring a
specified number of times per second. The number is expressed in Hertz (cycles per
second).
alternator - Answer A device for converting mechanical energy into alternating current
electrical energy. It may be called an ac or synchronous generator.
,alternator, battery charging - Answer An engine driven ac generator, usually self
regulating, and self rectifying which provides dc for the purposes of re-charging the
starting batteries, and provides power to engine control and monitoring systems. These
alternators are usually about 1 to 3 kW at either 12 volts or 24 volts in output.
altitude - Answer The vertical elevation relative to sea level at which the generating
system is operating.
altitude rating - Answer The maximum power recommended by the manufacturer for
satisfactory operation at a given altitude.
ambient temperature - Answer The air temperature of the surroundings in which the
generating system or other applicable electrical equipment operates. The ambient
temperature for optimum rating of components of the system may vary from device to
device.
American Bureau of Shipping (ABS) - Answer A marine classification and inspection
society which establishes various requirements for shipbuilding and for equipment
designed for shipboard use.
American Wire Gauge(AWG) - Answer The gauge used for designating the sizes of solid
copper wires used in the United States. It is the same as the Brown & Sharp gauge.
ammeter - Answer An instrument for measuring the magnitude of an electric current.
ammeter and voltmeter selector switch - Answer A switching device that permits
reading current or voltage in each of the three phases by using a single voltmeter or
ammeter.
amortisseur - Answer A permanently short-circuited winding consisting of conductors
embedded in the rotor poles of a synchronous machine and connected together at the
ends of the poles. It lends stability on load changes and paralleling and improves
machine efficiency.
ampacity - Answer The current-carrying capacity, expressed in amperes, of a wire,
cable, or bus bar under stated thermal conditions.
ampere - Answer The unit of electric current flow. One ampere will flow when one volt is
applied across a resistance of one ohm.
ampere-turn - Answer A unit of magnetizing force. The product of current flowing,
measured in amperes, multiplied by the number of turns in a coil or winding.
analog device - Answer A device that operates with variables, such as voltages and
pressures, represented by continuously measured quantities.
angle of operation - Answer The maximum deviation from horizontal at which an engine
operates in a given application.
,apparent power - Answer A term used to describe the product of current and voltage,
expressed in kilovolt amperes (kVA). The apparent power in kVA multiplied by the power
factor (PF) is the real power in kilowatts (kW).
artifical load - Answer Nonproductive electric power-absorbing devices, which are
connected to the generator to simulate or to supplement the actual load.
artifical load (reactive) - Answer Load banks to which devices that operate at a lower
power factor have been added. Generally, variable reactors are used so that the amount
of reactance can be adjusted to match the power factor of the actual load. Air core
reactors provide the most stable operation for testing purposes.
artifical load (resistive) - Answer Load banks usually consisting of heater coils or strip
heaters which operate only at a unity power factor.
artifical load (supplemental) - Answer A permanently installed load which is used to
supplement the existing load in installations where the electric set is operating at light
load (less than 30% of the generator's nameplate rating).
artifical load (water rheostat) - Answer A tank containing a salt or brine and water
mixture in which electrodes are submerged to create a load. The deeper the electrodes
are submerged into the mixture, the greater the load. To stabilize the load, the mixture
must not be allowed to boil. This type of artificial load operates at unity power factor.
audible alarm - Answer Horn, siren, bell or buzzer which is used to attract the attention
of the operator when a fault occurs in the electric power generating system.
automatic transfer switch - Answer A switch designed to sense the loss of one power
source and automatically transfer the load to another source of power.
auxiliary fuel pump - Answer A pump used to transfer fuel from remote storage to the
engine.
back pressure - Answer Exhaust system pressure resulting from a restriction to exhaust
gas flow.
base mounted fuel tank - Answer Fuel tank that is incorporated into the generating
system subbase.
batteries (parallel connected ) - Answer Two or more batteries whose terminals are
connected positive-to-positive and negative-to-negative, with the load connected across
the positive and negative leads. The available current is equal to the sum of the
individual battery current ratings, and the voltage is the voltage rating of one battery.
Only batteries of equal voltage rating may be connected in this manner.
batteries (series connected) - Answer Two or more batteries with the positive terminal
of one connected to the negative terminal of the next, with the load connected to the
negative terminal of the first battery and the positive terminal of the last battery in the
series. The voltage is equal to the sum of the voltage ratings of the individual batteries,
, and the current is limited to the rated current capacity of the smallest battery connected
in the circuit.
battery - Answer A device that transforms chemical energy into electric energy in a cell
with positive and negative electrodes in an electrolyte. Technically two or more cells
connected in series, but in common usage often applied to single cells..
battery (lead acid) - Answer A battery that uses lead as negative electrode lead dioxide
as positive electrode and sulfuric acid as electrolyte; nominal voltage 2 volts per cell.
battery (nickel cadmium) - Answer A battery that uses nickel oxide for positive electrode
and cadmium for negative electrode with an alkaline electrolyte; nominal voltage 1.2
volts per cell.
battery capacity - Answer A battery's ability to provide a specified current, for a given
time period, to a specified end voltage (ampere-hour rating)
battery cell failure - Answer The condition existing when a cell will provide less than 80%
of its original rated current capability as specified in the manufacturer's cell
performance data sheet.
battery charger - Answer Equipment used to restore the charge in storage batteries
battery rating (SAE lead acid) - Answer Ampere-hour rate, indicates the capacity of a
battery. The fully charged battery is brought to a temperature of 80* F and is discharged
at a rate equal to 1/20 of the published capacity in ampere-hours, until the voltage falls
to 1.75 volts per cell.
battery warmer - Answer Heater used in cold climates to maintain battery electrolyte
temperature.
block heater - Answer Coolant heating device which may be mounted in the engine
block and immersed in engine coolant, (immersion type heater) or mounted externally
and connected to the engine's coolant passages by means of piping or hoses (tank type
heater).
blower fan - Answer A fan positioned in a cooling system such that the air passes
through the fan before entering the radiator.
bonding - Answer A reliable connection to assure electrical conductivity (usually used in
grounding circuits).
brake horsepower - Answer The power available at the flywheel, or other output
member(s) for doing useful work.
brake specific fuel consumption - Answer (B.S.F.C.). The rate of fuel consumed by an
engine, divided by the flywheel power output. (Also referd to as Specific Fuel
Consumption)
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