A picture of an electrical box and the generator.

Glossary of Terms

We have compiled a list of commonly used terms for used diesel generators and surplus diesel generators.

We hope you find this information useful, and if you have any questions, give us a call at (208) 651-3584.

Vital Power & Equipment is your home for generators. We sell Used Generators and New Surplus Generators. Diesel and Natural Gas Generators. Emergency Standby and Portable Generators.

Glossary of Commonly Used Generator Parts and Terms

  • Alternating Current (AC)
    An electric current that 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 given 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 expressed in “kilovolt-amperes” (kVA). It is the product of voltage (volts) and current (amperes), it is both active and reactive power.
  • Backup Generator or Genset
    A generator used as an emergency power backup. 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 from 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 without any external power supply.
  • Brownout
    Is the commonly used term in the industry that refers to the reduction of voltage or power when the demand for electricity exceeds capacity.
  • Brush
    Consists of either graphite or copper conducting elements, which maintain the sliding electrical contact between the static and moving elements.
  • 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 is combined with overload relays
  • Core
    Comprises lamination in the generator that constitutes the magnetic structure.
  • Cradle
    Is often revered as the metal frame or cover enclosing the generator or engine to provide protection from external interferences.
  • Current
    The rate at which electricity flow
  • 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.
  • Emergency Power
    Commonly referred to as the “generator”. Emergency power is needed when there is a loss of electricity in a building or facility. The generator(s) supply 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, patients and personnel in a hospital.
  • Enclosure (AKA Housing)
    There are two common types of enclosures
    Sound Attenuated – A sound attenuated enclosure: an enclosure that is baffled or insulated to reduce the noise made from the generator.
    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 because it provides power or electrical current to a larger generator.
  • 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 in a circuit? Any additional load would be considered an overload.
  • 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 resources such as solar, wind and geothermal. Green electricity is non-polluting.
  • Grid
    The Commercial Utility’s electrical system is used for supplying power.
  • Hertz (Hz)
    Cycles per second, commonly referred to as frequency, North America runs 60 Hz.
  • 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 a device that supplies DC voltage to the spark plugs.
  • Inrush Current
    Is the immediate input current of 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.
  • Kilo-volt-amperes (kVA)
    kVA is an electrical term used to rate electrical devices. 1,000 Volt Amperes.
  • Kilowatt (kW)
    An alternate term for rating electrical devices. 1,000 watts
  • 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
  • Main Breaker
    Is the main circuit breaker at either the input or output of the bus, through 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 without power interruption.
  • Megawatt (MW)
    One million watts of power or electricity.
  • 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 Manufacturers Association (NEMA)
  • Natural Gas Generator: A generator that runs on Natural Gas and/or Propane
  • Used Natural Gas Generators: A used natural gas generator can save our clients time and a lot of money.
  • Ohm
    Is a unit of electrical resistance.
  • Ohmmeter
    Is the device used to measure electrical resistance?
  • On Set Paralleling
    Manuel paralleling systems that are built into the generator.
  • Overcrank
    A feature with most generators that displays an alarm when the generator fails to start.
  • 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 its electrical demand from the utility by using the backup 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%.
  • 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)
  • Single Phase
    Is an Alternating Current having two input terminals and two output terminals. Single-phase is often referred to as 110/220 volts or 120/240 volts.
  • 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 equipped with a DC exciter.
  • Tachometer
    An instrument that measures the 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 backup generator if the original source has failed.
  • Transformer
    A device commonly used to decrease or increase the voltage from the generator to match the facility's voltage
  • Underwriters Laboratories (UL listed)
    A non-profit, independent testing and certification organization.
  • Utility
    Your commercial power source. Your local “Utility” company.
  • Used Diesel Generators
    A good used diesel generator can save our clients time and a lot of money.
  • VITAL POWER AND EQUIPMENT
    Your #1 source for high-quality used diesel generators and natural gas generators.
  • Watt
    The unit used for measuring the true total electric power.
  • Winding
    Represents all the coils of a generator.