IEEE C37.010-1979 pdf free.IEEE Application Guide for AC High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis.
In the application of circuit breakers toelectrical sy stems, careful attention must begiven to many items of technical importance toassure that a misapplication does not occur. Inthe usual application, the principal function ofthe circuit breaker is to carry load current andprovide a means for the interruption of shortcircuit current. However，it may be used forfrequent load，exciting current,or capacitivecurrent . switching. In some cases，switchingrequirements may be the determining factor inselection rather than , the requirements ofshortcircuit current ..interruption. Specialattention ‘must also be given to applicationswhere frequent operations are essential.
In the selection of a circuit breaker, considera-tion must be given to the future as well as tothe present. needs for interrupting capacity andfor currentcarrying capability, These considera-tions . include the possibility of connectedcircuit changes,such as additions of supplemental cooling means for transformers or con-nection of multiple cable or overhead lines tothe breaker,or possible future transfer of thecircuit breaker from its initial postion to someother location.
In the United States，two types of circuitbreakers are available for use at most voltageratings. These types come under the generalclassification of oil ,and oilless power circuit breakers，and the preferred ratings available arelisted in ANSr C37.06-1979. The choice ofbreaker type may be influenced by such con-siderations asattended versus nonattendedoperation, contaminated atmosphere,location,maintenance, ease of handling the interruptingmedium, and cost of the installation.
Maximum Voltage for Application.Theoperating voltage and the normalfrequencyrecovery voltage should not exceed the ratedmaximum voltage, since this is the upper limitfor operation.
Voltage Range Factor.The voltage rangefactor，K, is published in ANSI C37.06-1979.In most cases,the voltage range is within therange commonly used. (See 4.10.)
Frequency. Rated frequency for circuitbreakers is 60 Hz.
At slightly lower frequencies,such as 50 Hz,themain current-carryingparts willbeadequate，but ac control devices may not besuitable for the application.At 25 Hz,the continuous current ratings inamperes are higher and are listed in ANSIc37.06-1979.
Interruption of fault currents on systemsoperating at frequenciesother than ratedfrequencymayrequire modification ofmechanisms to change speed of opening or mayrequire a change in interrupting ratings of thecircuit breakers.
In any case,special consideration should begiven to applications at frequencies differingfrom 60 Hz.IEEE C37.010 pdf download.