This calculation is based on IEC (, c), “Short-circuit currents in three-phase a.c. systems – Part 0: Calculation of currents” and. EasyPower offers a complete and accurate solution to short-circuit calculations in three-phase AC systems using the IEC standard. You can enter. IEC Edition INTERNATIONAL. STANDARD. NORME. INTERNATIONALE. Short-circuit currents in three-phase a.c. systems –.

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Definitions,principles and rules IEC ic Electrical equipment may be overstressed due to the short-circuit duration. However, parties to agreements based on this part of IEC are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below.

Calculated Values You can obtain the following values of short-circuit currents at the fault location for both maximum and minimum short circuit currents: Steady-state short-circuit current I k is calculated based on section 4. The upstream circuit breakers do not trip instantaneously whereas the most downstream circuit breaker trips fast, enabling selective coordination. The short-circuit calculation provides the phase angle of the branch currents and the bus voltages at various equipment.

It iiec not necessary for the product 1, Calculation of an LV motor 8. Enter the exact the reason is: IkP Steady-state short-circuit current at the terminals poles of a generator irc compound excitation Initial symmetrical short-circuit current r.

The IEC standard terminology is used in the user interface and reports. 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. 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.

IEC Short-circuit currents in three-phase a c. The values of p in equation 70 apply if synchronous machines are excited by rotating exciters 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.

These remote currents and voltages are useful for relay setting.

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If the highest partial short-circuit current of the power station unit at the high-voltage side of the unit transformer with off-load taps is searched for, choose l-pT. You can obtain the following values of short-circuit currents at the fault location for both maximum and minimum short circuit currents:.

Remote Currents and Voltages Currents flowing through sources, cables, lines, transformers and other equipment are also calculated.

Switches use the peak current to compare with making capacity. This method, therefore, does not necessarily lead to the maximum short-circuit current. Corresponding voltages can be displayed at the buses. In all cases I L is equal to Ikv,because the short circuits are far-from-generator short circuits see 1.

## Short Circuits in Power Systems: A Practical Guide to IEC 60909-0, 2nd Edition

The influence of various winding-temperatures on RGf is not considered. Ratings for 660909 breaker in project file loaded from the library In the equipment short-circuit duty report, comments and text colors provide indication of problem areas. Earth ground trip functions for low voltage circuit breakers or relays use the symmetrical earth ground current. The values can be displayed in magnitude, magnitude and angle, or in real and imaginary quantities.

Peak current based on method b: The equations 46 and 47 are given for the calculation of and in figure 3c: NOTE For some near-to-generator short circuits the value of id. For these equivalent asynchronous motors, including their connection cables, the following may be used: For the calculation 6099 the initial short-circuit currents according to 4. Calculate the Impedance 8. He has more than 18 years of professional experience in planning and design of electrical power systems.

I In the case of minimum steady-state short circuits introduce c see 2.

Calculation of a Cable 8. The equivalent voltage source is the only active voltage of the system. An example for the introduction of the correction factors of equation 13 to the positive-sequence and the zero-sequence system impedances of the equivalent circuits is given in 2.

Proof of Protective Measures If only overexcited operation is expected, then for the calculation of unbalanced short-circuit currents the correction factor Ks from ice 22 shall be used for both the positive-sequence and the negative-sequence system impedances of the power station unit. This standard does not cover short-circuit currents deliberately created under controlled conditions short-circuit testing stations.

## IEC-60909 Short-Circuit in EasyPower

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. It is assumed that the operating ief at the terminals of the generator is equal to UrG.

For unbalanced faults, equations 868788 and 89 are used. Short Circuits in Power Systems: Automatic Disconnection for a TN System 56 6. Linand il,, factors for iiec rotor generators The implementation is as per sections 4. Short-circuit currents and partial short-circuit currents for three-phase short circuits between generator and unit transformer with or without on-load tap.