Below I drew a simplistic view of a distribution transformer which supplies a particular public area for example some households and shops ect.:
Va, Vb and Vc are three phases(line voltages) of the transformer.
In my previous question I've asked about why balancing the line currents i.e making Ia, Ib and Ib close is important.
Now imagine Z1, Z2 and Z3 are initially same. Let's say they represent same type of electric owens. And we can say Ia, Ib and Ic are initially equal.
And now imagine one of the electric oven Z3 is plugged of from the mains.
In this case, will the system automatically equalize Ia, Ib and Ic again for the sake of a balanced system? Where and how is that done practically? Is there a control mechanism unit for that purpose?