The equations 46 and 47 are given for the calculation of and in figure 3c: A,,,,, may be obtained from figures 18 or 19 for cylindrical rotor generators or salient-pole generators. The following methods are supported for meshed networks as per section 4. Steady-state short-circuit current I k Steady-state short-circuit current I k is calculated based on section 4. Sequential short circuits are not considered.

 Uploader: Malagal Date Added: 18 October 2005 File Size: 12.82 Mb Operating Systems: Windows NT/2000/XP/2003/2003/7/8/10 MacOS 10/X Downloads: 12426 Price: Free* [*Free Regsitration Required] You can obtain the following values of short-circuit currents at the fault location for both maximum and minimum short circuit currents:.

Examples f o iec 60909-4 the calculation of short-circuit currents’ IEC Electric and magnetic devices IEC NOTE For some near-to-generator short circuits the value of id.

## IEC TR 60909-4:2000

If there are several transformers with slightly differing rated transformation ratios trT1trT EasyPower uses the equivalent voltage source at the short-circuit location, symmetrical components impedance network, and the voltage factor c as described in section 2. IEC- lire: Impedances 2, between the starpoint of transformers and earth are to be iec 60909-4 as 3 2, into the zero-sequence system without a correction factor.

The calculation of low-voltage breaking iec 60909-4 after a time deiay tmingreater than 0,1 s is not included in this standard; generator manufacturers may be able to provide information. Thus the network feeder in figure 4a is represented by its internal impedance Zot, transferred to the LV-side of the iec 60909-4 see 3. The correction factor Kso 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.

Short-circuit current-limiting reactors shall be treated as a part of the short-circuit impedance. This can lead to a situation where the partial short-circuit currents are too small to operate any further protection device, particularly in the case of minimum short-circuit currents. Annex A forms an integral part of this standard. Factor q may also be obtained from figure Example for the estimation of the contribution from the asynchronous motors in relation to the total short-circuit current Factors f o r the calculation of short-circuit currents iec 60909-4 three-phase a.

# IEC Short-Circuit in EasyPower

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 iec 60909-4 terminals poles Xd resp.

The generator impedance shall be transferred to iec 60909-4 high-voltage side using the rated transformation ratio t.

The program is designed to address short-circuits in meshed networks. Z THV is the impedance of the unit transformer referred to the high-voltage side without correct factor K T.

## IEC-60909 Short-Circuit in EasyPower

Special considerations are necessary in this case, for instance with the superposition method. Capacitors and non-rotating loads are not included in the calculations.