IEEE 958-2003 pdf download IEEE Guide for the Application of AC Adjustable-Speed Drives on 2 400 – 13 800 V Auxiliary Systems in Electric Power Generating Stations
3. Definitions
This clausc contains definitions used in this guide and are provided to stablish a common terminologyfor ASDs. Many of these terms and other elcctrical terms used in this guide are defined in TheAuthoratative Dictionary of IEEE Standards Terms.Seventh Edition B18.
3.1 adjustable-speed drive: An electric drive designed to provide easily operable means for speedadjustment of a motor within a specified speed range.
3.2 base operating point: Base operating point for motors defines a reference operating point at aspecified speed, frequency, fundamental voltage or current, and torque.3.3 base speed: The lowest speed obtained at rated load and rated voltage at the temperature risespecified in the rating.
3.4 channel: A single path for transmitting electric signals, usually in distinction from other parallelpaths.
3.5 characteristic harmonic: Those harmonics produced by semiconductor converter equipment in thecourse of normal operation on the ac input side of the converter, In a six-pulse converter, the cha-racteristic harmonics are the nontriplen odd harmonics, for example, the 5th, 7th, llth, 13th, and soon. In a twelvc-pulse converter, the characteristic harmonics are the llth 13th, 17th, 19th. and so on3.6 commutation: The transfer of the current from one converter switching branch to another.3.7 converter: An operative unit for electronic power conversion, comprising onc or more electronicswitching devices and any associated components. such as transformers, filters. commutation aids.controls.and auxiliaries.
3.8 current limiting: An overload protection mechanism that limits the maximum rms output current toa preset value, and automatically restores the output when the overload is removed.
3.9 displacement power factor: The ratio of the active power of the fundamental wave, in watts, toapparent power of the fundamental wave, in volt-amperes, that is required by the drive at theconnection point.
3.10 drive motor: The equipment used for converting available power into mechanical power suitablefor the operation of a machine.
3.11 drive system: Combination of the power converter (controller), motor, isolation element, and anymotor mounted devices.
3.12 dynamic braking: A system of clectric braking in which the cxcited machine is disconnected fromthe supply system and connected as a generator, the energy being dissipated in the winding and, ifnecessary.in a separate resistor.
3.13 efficiency: The ratio of load power to the total line power including the contribution of harmonicsand auxiliary equipment.
3.14 electric service source: The electrical network to which the drive is connected.3.15 flexible shaft system: Represents a shaft rotor combination when supported by bearings, an oilfilm, bearing brackets, or pedestals, housing and installed on a mounting base or foundation of definedstiffness that has a mechanical resonance below the minimum operating speed or within the operatingspeed range.
3.16 fundamental efficiency: The ratio of the fundamental load power to the fundamental line power.3.17 harmonic distortion (voltage and current): Nonlinear distortion of a system characterized by theappearance in the output of harmonics other than the fundamental component when the input wave issinusoidal.
3.18 harmonic distortion factor: The ratio of the root-can-square (rms) valuc of all the harmonics tothe rms value of the fundamental.