IEEE Std C37.20.3:2001 pdf free download

IEEE Std C37.20.3:2001 pdf free download.IEEE Standard for Metal- Enclosed Interrupter Switchgear.
The column head “dc withstand” is given as a reference only for using & test to verify the integrity 01 connected cable installations without disconnecting the cables from the switchgear It represents values believed to be appropriate and ipproumately equivalent lo the corresponding power frequency withstand test values specified for each voltage rating of switchgear. The presence of this column in no way implies any requirement fora dc withstand test on ac equipment or that a & withstand test represents an acceptable alternate to the power frequency withstand test specified in this standard, either for design test. producuofl test, conformance test, or field lest. When making dc tests, the voltage should be raised to the lest value in discrete steps and held for I mm.
hBecause of the variable voltage distribution encountered when making dc withstand tests, the manufacturer should be contacted for recommendations before applying de withstand to switchgear. Voltage transformers above 345 kV should be disconnected when testing with dc. See IEEE Std C57.13-PD93, Clause 8 and in particular 8.8.2, which reads. ikriodic kenotron test should not be applied to transformers of higher than 34.5 kV rating.”
5.4 Rated current
5.4.1 Rated continuous current
The rated continuous current ot MEl switchgear is the maximum current in rms amperes at rated frequency. which can be carried continuously by the primary circuit components. including buses and connections, without causing temperature rises in excess of specified limits for
a) Any primary or secondary circuit component
b) Any insulating rnedium,or structural orenclosing member
The specified ternperawre limits applicable to switchgear assemblies are given in 5.5.1 through 5.5.6.
5.4.2 Continuous current ratings
The preferred continuous current ratings of the main bus in MEl switchgear shall be 60() A. 1200 A, and 2000 A.
The continuous current rating of the individual switch compartments shall be equal to the ratings of the switching and interrupting devices used, except as may be modified by lower continuous current ratings for current transformers, power fuses, etc.
5.4.3 Rated momentary withstand current
The rated momentary withstand current of MEl switchgcar is the maximum rms total current that it shall be required to withstand. The current shall be the rms value, including the dc component. at the major peak of the maximum cycle as determined from the envelope of the current wave of the maximum offset phase during a test period of at least 10 cycles. The symmetrical current shall be the rated short-time current, and the peak current value shall be 2.6 times its rated short-time current at the major peak of the maximum cycle. (This is also referred to as the peak withstand current.)