The noise resulting from vibrations of laminations set by magnetic forces, is termed as

The degree of mechanical vibrations produced by the laminations of a transformer depends on

A

tightness of clamping

B

gauge of laminations

C

size of laminations

D

all of the above

The frequency of damped vibrations with viscous damping is ________ the frequency of undamped vibrations.

A

More than

B

Less than

C

Same as

D

None of these

In steady state forced vibrations, the amplitude of vibrations at resonance is __________ damping coefficient.

A

Equal to

B

Directly proportional to

C

Inversely proportional to

D

Independent of

The major reason of hydrodynamic noise (i.e., noise resulting from liquid flow) is

A

Pipe vibrations

B

Cavitation

C

Boundary layer separation

D

Fluctuation in liquid flow

Aerodynamic noise resulting from turbulent gas flow is the most prevalent source of valve noise in fluid ilow control. It is caused due to

A

Reynold stresses

B

Shear forces

C

Both A & B

D

Neither A nor B

If the resultant of two equal forces has the same magnitude as either of the forces, then the angle between the two forces is

A

30°

B

60°

C

90°

D

120°

Laminations of core are generally made of

A

Case iron

B

Carbon

C

Silicon steel

D

Stainless steel

Which of the following could be lamina proximately the thickness of laminations of a D.C. machine?

A

0.005 mm

B

0.05 mm

C

0.5 m

D

5 m

The thickness of laminations used in a transformer is usually

A

0.4 mm to 0.5 mm

B

4 mm to 5 mm

C

14 mm to 15 mm

D

25 mm to 40 mm

The transformer laminations are insulated from each other by

A

mica strip

B

thin coat of varnish

C

paper

D

any of the above

The noise resulting from vibrations of laminations set by magnetic forces, is termed as

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