Engineering
Engineering MCQs With Answers
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The operating characteristic of a Mho relay on an R-X diagram is a circle that:
AHas its center at the origin
BPasses through the origin
CDoes not intersect either axis
DEncloses the entire R-X plane
Where is the Buchholz relay physically mounted in an oil-immersed transformer installation?
AInside the conservator tank
BAt the bottom of the main oil tank
CIn the pipe connecting the main tank and the conservator tank
DOn top of the high-voltage bushings
The transient stability of a power transmission system can be improved by using:
ARemoving bundle conductors
BReducing system voltage
CHigh-speed circuit breakers and auto-reclosers
DIncreasing line reactance
In a symmetrical component transformation, zero-sequence current cannot flow in which transformer winding connection?
ADelta connection without ground
BSolidly grounded neutral star connection
CStar connection with low resistance grounding
DStar connection with grounded neutral
In a 3-phase induction motor, the ratio of rotor copper loss to rotor power input is equal to:
A1 / s
BSlip (s)
C1 - s
Ds^2
The maximum electromagnetic torque developed by a 3-phase induction motor is:
AInversely proportional to rotor resistance
BProportional to square of rotor resistance
CDirectly proportional to rotor resistance
DIndependent of rotor resistance
The total power capacity of two identical single-phase transformers connected in Open-Delta (V-V) configuration is what percentage of a closed delta bank?
A66.7%
B57.7%
C86.6%
D50.0%
The saving of copper in an auto-transformer compared to a conventional two-winding transformer with transformation ratio K (V2/V1 < 1) is proportional to:
A1 / K
BK
CK^2
D1 - K
Eddy current loss in transformer cores is minimized by:
AIncreasing supply current
BUsing thin laminated sheets insulated with varnish
CUsing solid cast iron cores
DIncreasing core thickness
Silicon steel is chosen for core construction in electrical machines because it offers:
AHigh electrical conductivity
BHigh mechanical copper strength
CLow resistance to eddy currents
DLow hysteresis loss and high magnetic permeability