GLOSSARY OF COMMONLY USED
GENERATOR PARTS AND TERMS
Welcome to Vital Power and Equipment. We have compiled a list of commonly used
and new surplus diesel generator terms. We hope you find this information useful and if
you have any questions give us a call (208) 209-5702.
[A]
Alternating Current (AC)
An electric current which changes direction with a regular frequency
Alternator
An electric generator that produces an alternating current, which uses
rotating parts to change the magnetic field to the alternating current.
Ambient Temperature:
The surrounding air temperature of the diesel generator in any giving area
Amperage
Is the strength (intensity) of an electrical current, which is measured in
amperes, commonly referred to as (AMPS)
Ampere
Named after the French physicist Andre M. Ampere. An ampere is a type
of electric current produced by one volt applied across a resistance of one
ohm.
Apparent Power
Measured in “volt amperes” and is often express in “kilovolt amperes”
(kVA). It is the product of voltage, (volts) and the current (amperes), it is
both active and reactive power.
[B]
Backup Generator or Genset
A generator used as emergency power back up. The best line of defense
for a power outage.
Battery
Is a group of usually two or more cells that are connected together to
provide an electrical current.
Battery Charger
A generator battery charger is different than the battery charger in your
vehicle. A generator battery charger is designed to maintain and supply a
constant float voltage to the battery to optimize the life of the battery.
Battery Charge Rectifier
The rectifier converts AC voltage to DC voltage to charge the battery.
Blackout
Refers to the sudden loss of all electrical power.
Black Start
This refers to the starting of the generator by way of its own power source
with out any external power supply.
Brownout
Is the commonly used term in the industry, which refers to the reduction of
voltage or power when the demand for the electricity exceeds capacity.
Brush
Consists of either graphite or copper conducting elements, which
maintains the sliding electrical contact between the static and moving
element.
[C]
Commutator
Is a device used in a generator to convert or “switch” the alternating
current that the generator produces into a direct current before the current
is sent to an external circuit.
Contactor
A device that uses a small control current to energize or de-energize the
load. The contactor is designed to handle high amounts of current and are
combined with overload relays
Core
Is comprised of laminations in the generator that constitute the magnetic
structure.
Cradle
Is often revered to the metal frame or cover enclosing the generator or
engine, to provide protection from external interferences.
Current
The rate that electricity flow
[D]
DC Generator
A generator that transforms mechanical energy into D-C electric energy
Decibel Level (DB)
Used in the industry to define noise level
Delta Connection
Delta connection is a three-phase connection where the beginning of each
phase is connected to the end of the next phase.
Diode
It is an electrical component with two active terminals called an anode and
a cathode. It allows the current to pass in only one direction. In addition
it converts AC power to DC power.
Direct Current
Is an electrical current that flows only in one direction.
Dynamo
Is simply an electric generator that produces a direct current.
[E]
Emergency Power
Commonly referred to as the “generator”. Emergency power is needed
when there is a loss of electricity to a building or facility. The
generator(s) supplies the “emergency power” to maintain operations which
could potentially save companies millions of dollars and save the lives of
those involved with a power outage, for example the patients and
personnel in a hospital.
Enclosure (AKA Housing)
There are two common types of enclosures
1) Sound Attenuated - A sound attenuated enclosure or is an
enclosure that is baffled or insulated to reduce the noise made from
the generator.
2) Weather Enclosure – A metal enclosure that is not sound- proofed
but is used to keep the outside elements from interfering with the
normal operations of the generator.
Exciter
Is known as an auxiliary generator, that provides power or electrical
current to a larger generator.
[F]
Frequency
Is the number of complete cycles of the alternating voltage per second.
Typically referred to as hertz (Hz)
Frequency Regulation
Measures the difference between a non-load and a full-load frequency as a
percentage of the full-load frequency.
Fuel Cell
A non-combustible device that converts the energy of a fuel to electricity
or heat.
Full Load
Is the maximum load of a generator of circuit. Any additional load would
be considered an overload.
[G]
Generator
A machine that converts mechanical energy into electrical energy.
Genset
A commonly used term for generator (see Generator)
Green Energy
Is the production of electricity from renewable resource such as solar,
wind and geothermal. Green electricity is non-polluting.
Grid
The Commercial Utility’s electrical system used for supplying power.
[H]
Hertz (Hz)
Cycles per second commonly referred to as frequency. North America
runs 60 Hz.
[I]
Idle Control
A device that the controls the idle speed of an engine in direct relation to
an electrical load.
Ignition Coil
The ignition coil is device that supplies DC voltage to the spark plugs.
Inrush Current
Is the immediate input current by a power supply when it is first turned on.
Insulation
The non-conductive material used to prevent the escape of the electric
current from a conductor.
Inverter
Changes DC power to AC power. Also known as a power converter.
[K]
• Kilo-volt-amperes (kVA)
o kVA is an electrical term used to rate electrical devices. 1,000 Volt
Amperes.
• Kilowatt (kW)
o An alternate term for rating electrical devices. 1,000 watts
[L]
Leg
Is the phase winding of a generator.
Load
Is the amount of electric power that various devices demand from the
electricity generator system.
Load Factor
The ratio derived from the average load to the generator power rating.
[M]
Main Breaker
Is the main circuit breaker at either the input or output of the bus, of which
all the bus power must flow.
Manual Bypass Switch
Is a switch that is manually operated to bypass electrical components in an
Uninterruptible Power Supply (UPS), so work can be done with out power
interruption.
• Megawatt (MW)
o One million watts of power or electricity.
[N]
N.E.C
National Electrical Code (NEC)
N.E.C.A
Is the National Electrical Contractors Association. (NECA)
N.E.M.A
Is the National Electrical manufactures Association (NEMA)
[O]
Ohm
Is a unit of electrical resistance.
Ohmmeter
Is the device used to measure electrical reistance.
On Set Paralleling
Manuel paralleling systems that is built onto the generator.
Overcrank
A feature with most generators that displays an alarm when the generator
fails to start.
[P]
Power Distribution Unit (PDU)
A device that monitors and controls the distribution of power to other
loads.
Peak Load
Is the maximum kW demand of a facility.
Peak Shaving
Is when a facility reduces it’s electrical demand from the utility by using
the back up generator during high demand times.
Power Factor
The ratio between the real power, kW and the apparent power, kVA in a
circuit. The standard power factor is shown as a percentage (.8) or 80%.
[R]
Reactive Power
Is the energy movement in an Alternating Current (AC) arising from the
production of electric and magnetic fields.
Rectifier
Is and electrical device that converts AC power to DC power.
Rotor
Is the rotating element of a generator or motor.
RPM
Is Revolutions Per Minute (RPM)
[S]
Single Phase
Is an Alternating Current having two input terminals and two output
terminals. Single phase is often referred to as 110/220 volt or120/240
volt.
Stator
Is the stationary part of a generator or motor. The direct opposite of a
Rotor (see rotor)
Surge
A sudden variation in frequency, current or voltage
Synchronized
The matching of one wave to the other by adjusting the phase angle and
frequency until the two coincide.
Synchronous Generator
Is an AC generator having a DC exciter.
[T]
Tachometer
An instrument that measures rotational speeds of a shaft or disk, usually
displayed as RPM’s.
Transfer Switch
Transfers the load from the original source, usually the utility, to the back
up generator if the original source has failed.
Transformer
A device commonly used to decrease or increase the voltage from the
generator to match the facilities voltage.
[U]
Underwriters Laboratories (UL listed)
A non-profit, independent testing and certification organization.
Utility
Your commercial power source. Your local “Utility” company.
[V]
VITAL POWER AND EQUIPMENT
Your #1 on source for high quality used or surplus, diesel and natural
gas generators.
[W]
Watt
The unit used for measuring the true total electric power.
Winding
Represents all the coils of a generator.