31.

32.

33.

34.

35.

36.

87.

38.

CRGO laminations in a transformer are used to minimise :

(ക) ‏براه‎ current loss (B) hysteresis [055
)0 0011 (ಗಿ) and (B) (D) 001800 1085
An Air-core transformer, as compared to iron core transformer, has +
(^) less magnetic core loss (B) more magnetic core 1088
(0 no magnetic core loss (D) less ohmic loss

Transformer maximum efficiency, for a constant load current, occurs at :
(^) 0.8 (8) 2௦ pf leading
(0 zero pflagging (D) पात्ति power factor

A de series motor is running .at rated speed with rated excitation. The motor has two
resistance R, and I, connected across the armature and the field respectively. Speeds above

the rated epeed can be achieved by :
(५) 080108811೯ 7] only (1) increasing R, only

(C) decreasing R, and increasing &, (D) increasing R, .and decreasing 40)

A de series motor ig running at rated speed without any additional resistance in series. If an
additional resistance i placed in series, the speed of the motor :

(ക) increases (B) decreases
(0 remains unchanged (D) oscillates around the rated speed

Plugging of de motors 1s normally executed by :
(ಗೆ) reversing the field polarity
(03) reversing the armature polarity
‏رم‎ reversing both armature and field polarity
(D) connecting a resistance across the armature

The direction of induced emf in an armature coil of a de machine is :
(ಸ) the same as that of the current for both the generator and the motor
(B) opposite to that of the current for the generator and the motor

(C) the same a= that of current for the generator and opposite to that of the current
for the motor

(10) none of these.

The wave form of the armature mmf in a de machine is : ⋅
(^) square 3 (13) rectangular
((7) triangular (D) sinuscidal
^
7 203/2014
17.1.0.1