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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The deviation depends on the configuration of the network.
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 3c and 3d the application of Ks according to equation 22 may lead to results at the non-conservative side. Read an Excerpt Excerpt 1: The factor p may also be obtained from figure Ik Steady-state short-circuit current r.
Depending on the product f. A contribution is also given if, in case of a power station unit, the short-circuit occurs on the high-voltage side of the unit transformer see figure 1lc.
Currents calculated with equation 74 are larger than the real symmetrical short-circuit breaking. The zero-sequence system impedance Z,, of the motor shall be given by the manufacturer, if needed see 4.
The correction factor Kso shall also be applied to the zero-sequence system impedance of the power 60909-00 unit excepting, if 6090-0, an impedance component between the star point of the transformer and earth.
The results of the short-circuit current calculation have an acceptable accuracy also in the case of untransposed overhead lines. Short Circuits in Power Systems: CE1 TR6090-0 read: For the calculation of the partial short-circuit current I L 2 feeding into the short-circuit location F2, for example at the connection to the high-voltage side of the auxiliary transformer AT in figure 13, it is sufficient to take: In this case special considerations beyond the scope and procedure given in this standard have to be taken into account see for instance 2.
Calculation of a Motor 8. Impedances 2, between the starpoint of transformers and 69009-0 are to be introduced as iiec 2, into the zero-sequence system without a correction factor.
If there are several transformers with slightly differing rated transformation ratios trT1trT The equivalent voltage source is 60990-0 only active voltage of the system. Help Center Find new research papers in: Within the accuracy of this standard, it is often sufficient to determine the short-circuit current at the short-circuit location F as being the sum of the absolute values of the individual partial short- circuit currents.
Short Circuits in Power Systems: A Practical Guide to IEC 60909-0, 2nd Edition
From the calculated initial symmetrical short-circuit current and characteristic curves of the fuses or current-limiting circuit- breakers, the cut-off current is determined, which is the peak short-circuit current of the downstream substation. In general, the calculation according to 4. That is why it is not possible to give an easy method of calculating i, and id. Added to Your Shopping Cart.
This part of IEC deals with the calculation of short-circuit currents in the case of balanced or unbalanced short circuits.
For currents during two separate simultaneous single-phase line-to-earth short circuits in an isolated neutral system or a resonance earthed neutral system, see IEC Calculation of currents 1 General 1. For per unit or other similar unit systems, no transformation is necessary if these systems are coherent, i. IEC Short-circuit currents in three-phase a c. The following values for the fictitious resistances RGfmay be used for the calculation of the peak short- circuit current with sufficient accuracy.
Rated short-circuit voltage of a transformer in per cent Short-circuit voltage of a short-circuit limiting reactor in per cent Rated resistive component of the short-circuit voltage of a transformer in per cent Rated reactive component of the short-circuit voltage of a transformer in per cent Positive- negative- zero-sequence voltage Reactance, absolute respectively relative value Synchronous reactance, direct axis respectively quadrature axis Fictitious reactance of a generator with compound excitation in the case of steady-state short circuit at the terminals poles Xd resp.
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If the long-term operating conditions of network transformers before the short circuit are known for sure, then the following equation 12b may be used instead of equation 12a. Factor p for calculation of short-circuit breaking current 660909-0, Then they contribute only to the initial symmetrical short-circuit current I: Factor n for the heat effect of the a.
At this date, the publication will be 0 reconfirmed; 0 withdrawn; 0 60909- by a revised edition, or 0 amended.
Proof of the Stability of Low-Voltage Systems Enter the exact the reason is: This correction factor ief not be introduced for unit transformers of power station units see 3. 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.
Click here to sign up. The values of positive-sequence and negative-sequence impedances can differ from each other only in the case of rotating machines. When calculating short-circuit currents in systems with different voltage levels, it is necessary to transfer impedance 6090-90 from one voltage level to another, usually to that voltage level at which the short-circuit current is to be calculated. This is the only active voltage of the network 1.
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I education ci military ci I other Despite these assumptions being not strictly true for the power systems considered, the result of the calculation does fulfil the objective to give results which are generally of acceptable accuracy. The short-circuit impedances for the examples in figures 1l b and 1I C are given by the following equations: The initial symmetrical short-circuit currents riQ,, and riQm, on the high-voltage side of the trans- former shall be given by the supply company or by an adequate calculation according to this standard.
Figure 1 – Short-circuit current of a far-from-generator short circuit with constant a. Calculation of ic Generator 8. ILR highest symmetrical r.