IEEE Std C37.20.4:2001 pdf free download

IEEE Std C37.20.4:2001 pdf free download.IEEE Standard for Indoor AC Switches (1 kV- 38 kV) for Use in Metal-Enclosed Switchgear.
NOTE this rating was previously called the rated momentary curreni and was an rum asymmetrical eurrcrn. In other documents this value may also be referred to and can be equated to ‘peak withstand currcnt.’ If the peak withstand current rating is 2.6 times thc rated short-time symmetrical current and the duration of the test is 10 cycles. thcn the requirement for “rated momentary withstand current” has been met. The new rated momentary withstand current is equiakni to the historic rated momcnt.iry currern, The rated momentary withstand current is shown as the iauIt.dostng and nmrnentary currcnt in
IEEE SW C37.22-l996,
5.10 Rated short-time withstand current
The rated short-time withstand current is the maximum symmetrical mis current at rated power frequency that the switch shall be required to carry for its rated duration. This is a measure of the ability of he switch to withstand the hcat and the forces generated by a short circuit current at its rated time duration.
5.11 Rated short-time withstand current duration
The rated short-time withstand current duration is the maximum duration that the switch shall be required to carry rated short-time withstand current while in the closed state.
5.12 Rated fault making current
The rated fault making current is the maximum instantaneous current at the first major peak of an offset rated power frequency current that the switch shall be required to makc and carry at its rated maximum voltage for a duration of 10 cycles. This value of current shall be the same as the rated momentary current of the switch.
5.13 Rated fault making current for integral switch and fuse
Switches equipped with fuses may be rated at prospective (available) short-circuit currents different from the unfused switch fault making ratings. The integral switch and fuse short-circuit current rating is the prospective peak current, which has been demonstrated by tests, that the combination switch and fuse can withstand during the faLik making test. During the fault making test to demonstrate the integral switch and fuse short-circuit current rating, the current duration is limited by the cleaning time of the fuse. The specific fuse types for which the integral short-circuit current rating has been estahli%hcd shall he specified,
5.14 Rated control voltage
The rated control voltage is the nominal voltage for which a power-operated mechanism is designed to operate when that voltage is applied to the terminals of the operating mechanism [IEEE Std 1247-1998].