Electrical Machine MCQ #16

1) The concentric type winding of transformer can be classified as
    A) continuous disc winding
    B) helical and crossover winding
    C) cylindrical winding
    D) all of the above

2) The winding of the transformer should be mechanically stable in respect of
    A) the force appearing when sudden short circuits of transformer occurs
    B) the force appearing load through off of transformer occurs
    C) load consumes too much reactive power
    D) none of the above

3) The transformer windings are made up of ______
    A) aluminum strip
    B) solid copper
    C) stranded copper
    D) all of the above

4) In transformer winding to reduce eddy current losses in the conductors______
    A) several series straps are preferred
    B) several parallel straps are preferred
    C) one large strap is preferred
    D) Both A or B


ANSWER: | 1-D | 2-A | 3-D | 4-D |

5) A sandwich type winding is employed for
    A) shell type transformer
    B) core type transformer
    C) step down transformer
    D) step up transformer

6) In core type transformer _____ winding is employed.
    A) sandwich type winding
    B) concentric type winding
    C) rectangular type winding
    D) all of the above

7) Which one of the following has the better magnetic properties in the direction of rolling?
    A) cold rolled steel
    B) hot rolled steel
    C) cast iron
    D) aluminium

8) The thickness of lamination of transformer core varies from _____
    A) 0.35 mm to 0.5 mm
    B) 0.25 mm to 0.35 mm
    C) 0.45 mm to 0.55 mm
    D) 0.55 mm to 0.65 mm


ANSWER: | 5-A | 6-B | 7-A | 8-A |

9) The thickness of lamination should not be below 0.3 mm because
    A) the lamination becomes mechanically strong and tends to buckle
    B) the lamination becomes mechanically weak and tends to buckle
    C) the lamination becomes electrically strong and tends to buckle
    D) the lamination becomes electrically weak and tends to buckle

10) In high capacity transformer, varnish insulation is used instead of paper insulation because of paper insulation
    A) occupies too large percentage of the stack cross section
    B) its heat resisting and heat conducting properties are worse
    C) its mechanical strength is worse
    D) all of the above

11) What are the most important requirements of winding of the transformer?
    A) efficiency of transformer in services
    B) economical in initial cost with view of market availability of copper
    C) heating conditions of winding should meet standard requirements
    D) all of the above

12) A part of the magnetic circuit which carry the transformer winding are called_____
    A) yoke
    B) limbs
    C) legs
    D) Both B and C


ANSWER: | 9-B | 10-D | 11-D | 12-D |