(1) The design presented are valid for WEG transformers, class of insulation of 15 kV. Other situations, on request.
(2) The short-circuit level supplied is calculated on the transformer secondary terminals, considering only its impedance.
(3) The tables are limited to 1500kVA once on larger output rating transformers, design are done, on most cases, as per customer specification. On this case, installation short-circuit level may change significantly.
(4) The distribution circuit breakers may be selected for the rated current values given on the sample table limited to the short-circuit interruption capacity version selected for each transformer.
(5) On substations with two or more transformers connected in parallel at the lower voltage, for short-circuit level determination, you should consider the sum of outputs in kVA and the average of the percentage impedance values Z (%).
(6) An overload factor of 15% was taken into account in order to dimension the transformer low voltage circuit breaker.
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