Electrical Machines
A transformer core is made up of a silicon steel laminations which has maximum flux density 1 Tesla. If it was cold rolled grain oriented its flux density increases to 1.6 Tesla. What is the saving in core size or area due to cold rolled grain oriented process?

 68%
 40%
 38%
 60%

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Electrical Machines
The residual magnetism of a self-excited dc generator is lost. To build up its emf again

 the field winding must be replaced
 field winding must be excited by low voltage dc supply
 the field winding connection must be reversed
 the armature connection must be reversed

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