IEC 60909-0 PDF
CE1 IEC (Première édition – ) (First edition – ) Courants de court-circuit dans les réseaux Short-circuit currents in three-phase. IEC Edition INTERNATIONAL. STANDARD. NORME. INTERNATIONALE. Short-circuit currents in three-phase a.c. systems –. Buy IEC SHORT-CIRCUIT CURRENTS IN THREE-PHASE A.C. SYSTEMS – PART 0: CALCULATION OF CURRENTS from SAI Global.
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Operational data and the load of consumers, tap- changer position of transformers, excitation of generators, and so on, are dispensable; additional calculations about all the different possible load flows at the moment of short circuit are superfluous.
Log In Sign Up. When calculating the partial short-circuit current I: Short-circuit currents and short-circuit impedances may also be determined by system tests, by measurement on a network analyzer, or with a digital computer.
Connection of a Motor When using this method in meshed networks with transformers, generators and power station units, the impedance correction factors KT,KG and Ks, respectively Kso, shall be introduced with the same values as for the 50 Hz or 60 Hz calculations.
The correction factor Ks shall also be applied to the zero-sequence system impedance of the power station unit, excepting, if present, an impedance component between the star point of the transformer and earth. The total short-circuit in F1 or F2 figure 13 is found by adding the partial short-circuit current ILrnv, caused by the medium- and low-voltage auxiliary motors of the power station unit. This is the only active voltage of the network 1.
When calculating short-circuit currents in systems with different voltage levels, it is necessary to transfer impedance values from one voltage level to another, usually to that voltage level at which the short-circuit current is to be calculated.
Short Circuits in Power Systems: A Practical Guide to IEC 60909-0, 2nd Edition
The effective resistance of the stator of synchronous ied lies generally much below the given values for RGf. Systems at highest voltages of kV and above with long transmission lines need special consideration. In this case the Joule integral is determined from the characteristic of the current-limiting device.
The values of p in equation 70 apply if synchronous machines are excited by rotating 60099-0 or by static converter exciters provided, for static exciters, the minimum time delay tminis less than 0,25 s and the maximum excitation voltage is less than 1,6 times rated load excitation-voltage.
At this date, the publication will ieec 0 reconfirmed; 0 withdrawn; 0 replaced by a revised edition, or 0 amended. Short-circuit current-limiting reactors shall be treated as a part of the short-circuit impedance. T JSrT ; t, is the rated transformation ratio of the unit transformer: Rated voltage, line-to-line r. Examples f o r the calculation of short-circuit currents’ IEC CE1 TR–I read: The factor n in figure 22 is given by: If underexcited operation of the power station unit is expected at some time for instance to a large extent especially in pumped storage plantsthen only when calculating unbalanced short- circuit currents with earth connection see figures ie and 3d the application of Ks according to equation 22 may eic to results at the non-conservative side.
06909-0 decaying aperiodic component id. For simplification of the calculation, groups of motors including their connection cables may be combined to a single equivalent motor see motor M4 in figure 9. With uec impedances the corrected equivalent impedances LK, z B K and ZCKshall be calculated using the procedure given in equation i i.
While using fuses or current-limiting circuit-breakers to protect substations, the initial symmetrical short- circuit current is first calculated as if these devices were not available. For balanced and unbalanced short circuits as shown in figure 3, it is useful to calculate the short-circuit currents by application of symmetrical components see 2.
Electric and magnetic devices IEC When a number of short circuits occur with a short time interval in between them, the resulting Joule integral is the sum of the Joule integrals of the individual short-circuit 6090-90, as given in equation 1 Figure 2 – Short-circuit current of a near-to-generator short circuit with decaying a.
Figure 21 – Factor m for the heat effect of the d. Help Center Find new research papers in: In a near-to-generator short circuit, the short-circuit current behaves generally as shown in figure 2.
For this calculation method, an equivalent voltage source at the short-circuit location is introduced. For simplification, it is permitted to use the same value for IC as for the three- phase short circuit. The symbols 609909-0 physical quantities possessing both numerical values and dimensions that are independent of units, provided a consistent unit system is chosen, for example the international system of units SI.
That is why it is not possible to give an easy method of calculating i, and id. NOTE The following values for resistivity may be used: