What is the Over current coefficient (Ksi) for a current transformer? What is its relevance in current transformer feasibility?

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The Over current coefficient (Ksi) of a current transformer can be defined in terms of its rated primary and short time withstand current as follows:

Knowing the value of this factor allows us to know whether a CT will be easy to manufacture or otherwise as follows:

The lower Ksi is, the easier the CT will be to manufacture.
A high Ksi leads to over-dimensioning of the primary winding's section; the number of primary turns will therefore be limited together with the induced electromotive force; the CT will be even more difficult to produce.