11.The insulation between windings and grounded core and the insulation between the windings of the same phase is called

12.A current density of _____ is ilsed for large power transformers with forced circulation of oil or with water cooling coils

13.The cylindrical windings using circular conductors are used for current rating of

14.The cold rolled grain oriented steel has ______ permeability in the direction of the grain orientation.

15.The voltage control in electric supply networks in required on account of which of the following reasons ?