Related Questions

A single phase transformer has a maximum efficiency of 90% at full load and unity power factor. Efficiency at half load at the same power factor is -
A 87.8%
B 86.7%
C 88.26%
D 88.9%
A synchronous motor installed at the receiving end substation operates with such an excitation that it takes power at lagging power factor. Now if the applied voltage of the synchronous motor goes down, the power factor of the synchronous motor will
A remain same
B go down
C improve
D none of the above
Power factor of a synchronous motor is unity when
A the armature current is maximum
B the armature current is minimum
C the armature current is zero
D none of the above
A Circuit having power factor of 0.8 consumes 40W. The value of reactive power (VAR) is-
A 20
B 40
C 30
D 10
If in a synchronous motor, driving a given mechanical load and drawing current at a leading power factor from constant voltage supply its field excitation is increased, its power factor
A will become more
B will become less
C will remain unchanged
D none of the above.
If in a synchronous motor, driving mechanical load and drawing current at lagging power factor from constant voltage supply, its field excitation is increased, then its power factor
A become more
B become less
C remain constant
D none of the above
In vibration isolation system, the transmissibility will be equal to unity, for all values of damping factor, if $$\frac{\omega }{{\omega {\text{n}}}}$$ is
A Equal to 1
B Equal to 2
C Less than 2
D Greater than 2
If the damping factor for a vibrating system is unity, then the system will be
A Over damped
B Under damped
C Critically damped
D Without vibrations
The transmissibility, for all values of damping factor, will be less than unity, if $$\frac{\omega }{{\omega {\text{n}}}}$$ is
A Equal to 1
B Less than 2
C Equal to 2
D Greater than 2
The power factor indicates how much of the apparent power is reactive power.
A True
B False

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