IEEE C37.96-2012 pdf download IEEE Guide for AC Motor Protection
closed-transition transfer (parallel transfer): An MBT, designed to close the new source breaker beforetripping the old source breaker with the result that both source breakers are closed briefly at the same timeduring the transfer process.
commutation: The transfer of current from one switching device to another. Line-commutation utilizes theac system voltage for the transfer of current from one device to another. Self-commutation is achieved byutilization of the turn-off switching capability of a device such as an insulated-gate bipolar transistor(IGBTYgate turn-off thyristor (GTO). or gate-controlled turn-off thyristor (GCT). These devices caninterrupt a current The interruption forces the current to flow through another device
converter: A machine or device for changing ac power into dcC power (rectifier operation) or dc powerinto ac power (inverter operation). Other types of converters can change ac power directly to an ac powerof a different frequency (cycloconverter).
current limiting fuse (CL): A fuse that limits the peak-let-through current to less than the prospectivecurrent, CL fuscs are uscd on low-voltage and medium-voltage motors as primary fault protection deviccand on some small motors as fault and overload protection devices
current source converter: A current source converter is characterized by a controlled dc current in thintermediate dc link. The line side network voltage is converted in a controlled dc current. A current sourceconverter uses an SCR bridge or an active front end to control the de current.
current source inverter (CSI): An inverter, in which the de terminal is inductive and, as a consequence.the dc current is relatively slow to change. Modulation of the CSI acts to control the voltage at the acterminal The switches in a CSI need to block either voltage polarity, but are only required to conductcurrent in one direction.
damper winding limited: A synchronous motor that is thermally limited by its damper winding
drive: The equipment used for converting electrical power into mechanical power suitable for the operationof a machine.A drive is acombination of a conyerter and any motor-mnounted auxiliary devices.Sometimes a motor may be a part of the complete drive system. Examples of motor mounted auxiliarydevices are encoders,tachometers, thermal switches and detectors, air blowers, heaters, and vibrationsensors.
fast transfer – supervised: An open-transition method wherein the close is supervised to check that theyoltage phase angle difference between the motor bus voltage and the new source voltage is within apredetermined acceptable limit
fast transfer – unsupervised: An open-transition method wherein the close is implemented without async-check device or implemented with sync-check relays with performance and response time which maybe inadequate
field weakening range: Defincs when a motor is opcrated at a speed above its namcplate r/min, the drivcnecds to hold nameplatc voltage while increasing the frequency thus weakening the rotor field (air gapflux). This is also known as the constant horsepower range.
field winding: The rotor circuit on an ac synchronous motor, which consists of winding connected to a dcsource and produces the main electromagnetic field of the motor.
harmonic: A sinusoidal component of a periodic wave or quantity having any frequency within thespectra. There are three basic classes of harmonics: frequencies with an integer multiple of the fundamentalfrequency, frequencies with a non-integer multiple of the fundamental frequency (inter-harmonics), andfrequencies that are below the fundamental frequency (sub-harmonics).