Page 276 - Electrical Engineering Dictionary
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direction of a fault, thus allowing the defect  fault secure  pertaining to a circuit, with
                              to be located.                         respect to a set of faults, if and only if for
                                                                     any fault in this set, and any valid input code
                              fault kva  fault kilovolt-amps (kva) is the  the output is a non-code or correct code (the
                              fault level expressed in terms of volt-amps  output is never an invalid code). The circuit
                              rather than amps. One advantage of using  is considered to operate properly if the output
                              volt-amps rather than amps is that the same  is a code word.
                              flow is experienced on both sides of a trans-
                              former when expressed in volt-amps, while  fault simulation  an empirical method
                              the flow changes due to the transformer turns  used to determine how faults affect the op-
                              ratio when it is expressed in amps. Volt-  eration of the circuit and how much testing is
                              amps for a three-phase fault are expressed  required to obtain the desired fault coverage.
                              as 1.73 × rms line-line voltage × rms sym-
                              metrical fault current. Volt-amps for a single  fault tolerance  correct execution of a
                              phase fault are defined as 1.73 × rms line-  specified function in a circuit (system), pro-
                              line voltage × rms symmetrical current in the  vided by redundancy despite faults. The re-
                              faulted phase.                         dundancy provides the information needed to
                                                                     negate the effects of faults.
                              fault latency  the length of time between
                              the occurrence of a fault and the appearance  fault tree  the identification and analysis
                              of an error.                           of conditions and factors that cause or con-
                                                                     tribute to the occurrence of a defined undesir-
                              fault masking  a technique that hides the  able event, usually one that significantly af-
                              effects of faults with the use of redundant  fects system performance, economy, safety,
                              circuitry or information.              or other required characteristics.

                              fault mva  fault megavolt-amps (mva) is
                                                                     fault-tolerant control system  a system
                              thefaultlevelexpressedintermsofvolt-amps
                                                                     that exhibits stability and acceptable perfor-
                              rather than amps. One advantage of using
                                                                     mance in the presence of component faults
                              volt-amps rather than amps is the same flow
                                                                     (failures) or large changes in the system that
                              is experienced on both sides of a transformer
                                                                     resemble failures.
                              when expressed in volt-amps, while the flow
                              changes due to the transformer turns ratio
                                                                     fax  abbreviation for a machine that makes
                              when it is expressed in amps. Volt-amps for
                                                                     and transmits facsimiles. See facsimile.
                              a three-phase fault are expressed as 1.73 ×
                              rmsline-linevoltage×rmssymmetricalfault
                                                                     FCA    See fixed channel assignment.
                              current. Volt-ampsforasinglephasefaultare
                              defined as 1.73 × rms line-line voltage× rms
                                                                     FCM    See fuzzy cognitive map or fuzzy
                              symmetrical current in the faulted phase.
                                                                     c-means.
                              fault prevention  any technique or process
                              that attempts to eliminate the possibility of  FCT  See field controlled thyristor.
                              having a failure occur in a hardware device
                              or software routine.                   FDD    See frequency division duplex.

                              fault resistance  the resistance that occurs  FDDI  See fiber distributed data interface.
                              at the point of fault due to voltage drop across
                              an arc or due to other resistance in the fault  FDM  Seefrequencydivisionmultiplexing.
                              path.



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