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.
|Published (Last):||11 June 2018|
|PDF File Size:||6.78 Mb|
|ePub File Size:||3.24 Mb|
|Price:||Free* [*Free Regsitration Required]|
This book is a practitioner’s guide intended for students, electrical engineers, engineers in power technology, the electrotechnical industry, engineering consultants, energy suppliers, chemical engineers and physicists in industry. Description Reflecting the changes to the all-important short circuit calculations in three-phase power systems according to IEC standard, this new edition of the practical guide retains its proven and unique concept of explanations, calculations and real-life examples of short circuits in electrical networks.
Calculation of Short-Circuit Currents I k autre s The calculation of low-voltage breaking currents after a time deiay tmingreater than 0,1 s is not included in this standard; generator manufacturers may be able to provide information.
IEC | IEC Webstore
Despite these assumptions being not strictly true for the power systems considered, the result of the calculation does fulfil the objective to give ie which are generally of acceptable accuracy.
In general, two short-circuit currents, which differ in their magnitude, are to be calculated: In this case, the three-fold zero-sequence current flows through the joint return.
As long as RIX remains smaller than 0,3 in all branches, it is not necessary to use the factor 1, For simplification, it is permitted to use the same value of Kas for the three-phase short circuit. Help Center Find new research papers in: The following values for the fictitious resistances RGfmay be used for the calculation of the peak short- circuit current with sufficient accuracy. For grounded systems the influence of motors on the line-to-earth short-circuit current cannot be neglected.
Radial Network Example of a meshed network fed from several sources 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.
Short Circuits in Power Systems: A Practical Guide to IEC 60909-0, 2nd Edition
Symmetrical locked-rotor current irc an asynchronous motor Rated current of electrical equipment Thermal equivalent short-circuit current d. In the calculation of short-circuit currents, those medium-voltage and low-voltage motors may be neglected, provided that, according to the circuit diagram interlocking or to the process reversible drivesthey are not switched in at the same time.
The peak short-circuit current i, at a short-circuit location F, fed from sources which are not meshed with one another, in accordance with figure 12, is the sum of the partial short-circuit currents: They do not contribute to the iiec short-circuit breaking current I, and the kec short-circuit current I k.
The impedance correction factor shall be applied also to the negative-sequence and the zero- sequence impedance of the transformer when calculating unbalanced short-circuit currents.
Investigations of non-simultaneous short circuits, which may lead to higher aperiodic components of short-circuit current, are beyond the scope of this standard.
Connection Box to Service Panel If synchronous motors have a voltage regulation, they are treated like synchronous generators.
The need for the calculation of minimum short-circuit currents may arise because of underexcited operation of generators low-load condition in cable systems or in systems including long overhead lines, hydro pumping stations.
T JSrT ; t, is the rated transformation ratio of the unit transformer: Any branch may be a series combination of several impedances.
I librarian researcher I design engineer safety engineer ci Q7 Please assess the standard in the I following categories, using testing engineer ci the numbers: Automatic Disconnection for a TN System 56 6. Single-fed short circuits supplied by a transformer according to figure 4, may a priori be regarded as far- from-generator short circuits if X, 2 Ur, with XQ, calculated in accordance with 3. Electric and magnetic devices IEC Figure 2 – Short-circuit current of a near-to-generator short circuit with decaying a.
This is admissible, because the impedance correction factor KTfor network transformers is introduced.
Short-circuit impedances of a three-phase a. For the calculation of the initial short-circuit currents according to 4.
Figure 3 – Characterization of short circuits and their currents Figure 4 shows an example of the equivalent voltage source at the short-circuit location F as the only active voltage of the system fed by a transformer without or with on-load tap-changer. Calculation of a Cable 8.
The estimation according to equation 28 is not allowed in the case of three-winding transformers. Earthing and 6090-90 against electric shock IEC The impedance ZrS1in equation 38 or 43 is used to determine the partial short-circuit current ILT in figure 13 for the short circuit in F3.
Characterization of short circuits and their currents U, is the nominal voltage of the system; ur, is the rated voltage of the generator; ZGK is the corrected subtransient impedance of the generator; 2, is the subtransient impedance of the generator in the positive-sequence system: