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UL 347-2020 pdf free download
UL 347-2020 pdf free download.Medium-Voltage AC Contactors Controllers and Control Centers.
3.7.102 breaking capacity (of a switching device or a fuse): A value of prospective current that a switching device or a fuse is capable of breaking at a stated voltage under prescribed conditions of use and behavior. (IEC 60050-441:1984,441-17-08]
NOTE 1: The voltage to be stated and the conditions to be prescribed are dealt with in the relevant publications.
NOTE 2: For switching devices, the breaking capacity can be termed according to the kind of current included in the prescribed conditions, e.g., line charging breaking capacity, cable charging breaking capacity, single capacitor bank breaking capacity, etc.
3.7.103 making capacity (of a switching device): A value of prospective making current that a switching device is capable of making at a stated voltage under prescribed conditions of use and behavior
NOTE: The voltage to be stated and the conditions to be prescribed are dealt with in the relevant specifications.
3.7.104 take-over current: See Clause 3.7.115.
3.7.105 short-tIme withstand current: The current that a circuit or a switching device in the closed position can carry during a specified short time under prescribed conditions of use and behavior. jIEC
3.7.106 recovery voltage: The voltage that appears across the terminals of a pole of a switching device ora fuse after the breaking of the current. (IEC 60050-441:1984, 441-17-25. modifiedJ
NOTE: This voltage can be considered In two successive Intervals of time, the first In which a transient voltage Is supenmposed on an essentially constant power-frequency voltage. followed by a second interval in which the power-frequency or the steady-state recoveiy voltage alone exists.
3.7.107 transIent recovery voltage (TRV): The recovery voltage during the time in which it has a significant transient character. [IEC 60050-441:1984, 441-17-26)
NOTE 1: The transient recovery voltage can be oscillatory or non-oscillatory, or a combination 04 these, depending on the characteristics of the circuit and the switching device. It includes the voltage shift of the neutral of a polyphase circuit.
NOTE 2: The transient recovery voltage in three-phase circuits is, unless otherwise stated, that across the first pole to clear, because this voltage is generally higher than that which appears across each of the other two poles.
3.7.108 power-frequency recovery voltage: The recovery voltage after the transient voltage phenomena have subsided. [IEC 60050-441:1984, 441-17-27] See Figure 6.
3.7.109 prospective current (of a circuit and with respect to a combination situated therein): The current that would flow in the circuit if each pole of the combination were replaced by a conductor of negligible impedance. (IEC 60050-441:1984. 441-17-01, modified]UL 347-2020 pdf free download.
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