IEEE C37.100-1992 (R2001) pdf free.IEEE Standard Definitions for Power Switchgear.
IEEE C37.100 The terms and definitions in the standard are intended to encompass the products within the scope of the C37 projectthat include power switchgear for switching，interrupting，metering,protection, and regulating purposes as usedprimarily in connection with generation, transmission, distribution, and conversion of electric power.
The definitions of terms and explanatory notes relating thereto contained in this standard are not intended to embraceall possible meanings of the terms. They are intended for the sole purpose of establishing only those meanings of termsused in switchgear standards. They do not purport to embrace other meanings that the terms may properly have whenused in connection with other subjects.
In some instances, terms and definitions that are not identical to those in this standard have been developed by otherbranches of industry. Where this situation exists, the definitions in this standard shall be used for power switchgearwithin the C37 product scope.
In this standard, preferred terms are in some instances followed by less favored or alternate terms in parentheses.Alsosince the terms are arranged alphabetically, application phrases have been parenthetically appended to many terms.
For definitions of terms of related component parts, accessories, etc., not covered in this standard, reference should bemade to standards covering those products; for example, IEEE C57.13-1978, and IEEE Std 21-1976.
automatic transfer (or throw-over) equipment of the nonpreferential type: Automatic transfer equipment thatautomatically retransfers the load to the original source only when the other source, to which it has been connected,fails.
automatic transfer (or throw-over) equipment of the selective-preferential type: Automatic transfer equipment inwhich either source may serve as the preferred or the emergency source of preselection as desired, and which willretransfer the load to the preferred source upon its reenergization.backup protection (as applied to a relay system): A form of protection that operates independently of specifiedcomponents in the primary protective system.
It may duplicate the primary protection or may be intended to operateonly if the primary protection fails or is temporarily out of service.balance beam (of a relay): A lever form of relay armature, one end of which is acted upon by one input and the otherend restrained by a second input.IEEE C37.100 pdf download.