Question

why high leakage reactance transformer has drooping characteristics

Answer 1

Leakage flux is the flux which is leaked from Core of electrical machine and largely follows a path from air and occurs due to improper winding of coil(It's unavoidable we can reduce it but can't make it zero)..



As path followed by this flux is mostly from air medium so the flux and the voltage induced by it vary linearly with primary current. It can therefore said as primary leakage inductance L leakage(equal to the leakage-flux linkage with the primary per unit of primary current).L leakage(Ll) = (Leakage flux)/(primary current). So corresponding primary leakage reactance Xl is.Xl = 2 pi* f*Ll

Now,when we apply terminal voltage(V) on primary side, Ideally total voltage should come across winding but it isn't true practically some part of applied voltage is drop due to voltage drop in leakage reactance ( I * Xl).This is the effect due to leakage flux.

Same effect is observed on secondary side and it same in other type of electrical machine(IM, Synchronous machine)