IEEE C37.04-1979 pdf free.An American National Standard IEEE Standard Rating Structure for AC High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis.
Rated Interrupting Time. The rated interrupting time of a circuit breaker is the maxi-mum permissible interval between the energizingof the trip circuit at rated control voltage andthe interruption of the main circuit in all poleson an opening operation，when interrupting acurrent within the required interrupting capabilities and equal to 25 percent or more ofthe required asymmetrical interrupting capability at rated maximum voltage. At duties below2percent ofthe required asymmetricalinterrupting capabilityat rated maximumvoltage, the circuit shall be interrupted, but thetime required for interruption may be greaterthan the rated interrupting time by as much as50percent for 5 and 8 cycle breakers and1 cycle for breakers of 3 cycles and less. Forbreakers equipped with resistors, the interrupt-ing time of the resistor current may be longer.The interrupting time for a close-open operation at a specified duty shall not exceed therated interrupting time by more than 1 cyclefor 5 and 8 cycle breakers and cycle forbreakers of 3 cycles and less. When time isexpressed in cycles, it shall be on a 60 Hz basis.
Rated Permissible Tripping Delay Y.Therated permissible tripping delay of a circuitbreaker is Y seconds and is the maximum valueof time for which the circuit breaker is re-quired to carry K times rated short-circuitcurrent after closing on this current and beforeinterrupting. For values, see ANSI C37.06-1979. Permissible Tripping Delay T. Trippingof the circuit breaker may be delayed beyondthe rated permissible tripping delay at lowervalues ofcurrent in accordancewith thefollowing formula:The aggregate tripping delay on all operationswithin any 30 minute period must not exceedthe time obtained from the above formula.Determine the envelope of the short circuitcurrent through the breaker， against time,and obtain the rms values from 7.i.6 of ANSI/IEEE C37.09-1979.
Square the latter values and obtain the cor-responding curve.: Integrate this(idt) forvarious values of delay periods T. (See ANSI/IEEE C37.09-1979.) The value of T for whichthe integral equals Y times K times rated short-circuit currentsquared is the permissibletripping delay.
Rated Reclosing Time.The rated reclosingtime of a circuit breaker is the shortest reclosing time which the breaker is required tomeet with rated control voltage and ratedfluid operating pressure applied.See ANSIC37.06-1979.
Short-Circuit Rating. The short-circuitrating of a circuit breaker is established by thesymmetrical component of short-circuitcurrent in rms amperes,designated rated short-circuit current,to which all requiredshort-circuit capabilities are related.All valuesapply to both grounded and ungroundedshort circuits on predominantly inductive orresistive3-phase circuits witha normalfrequency phase-to-phase recovery:: voltageequal to the operating voltage.IEEE C37.04 pdf download.