NEW
Font size
WorksheetsDC Generator EEE430
Total questions: 10
Worksheet time: 5mins
Which type of excitation in a DC generator uses an independent external source for the field winding?
Shunt
Series
Compound
Separately excited
What is the usual range of field current in a separately excited DC generator compared to the rated armature current?
10–15%
5–7%
1–3%
20–25%
What role does residual magnetism play in a self-excited DC generator?
Improves efficiency
Initiates the self-excitation process
Reduces eddy current losses
Maintains field current during faults
Why must the generator speed be maintained between 1000 and 1500 rpm during testing?
To keep the temperature constant
To ensure consistent induced EMF for accurate readings
To reduce torque pulsations
To protect the rheostat from overload
When measuring no-load characteristics, why are both increasing and decreasing excitation currents recorded?
To test insulation strength
To observe magnetic hysteresis behaviour
To verify torque readings
To calculate efficiency
What is the function of the shunt rheostat (Rmy) in the experiment?
To vary armature resistance
To control field current and adjust generator voltage
To regulate speed
To measure current flow
In the external characteristic of a separately excited DC generator, why does the terminal voltage drop slightly as load current increases?
Due to voltage drop across armature resistance (IBRA)
Because speed decreases
Due to magnetic saturation
Because field current weakens
Why does a shunt-excited DC generator show a greater voltage drop under load compared to a separately excited generator?
Armature reaction is absent
Field current increases with load
Both armature resistance drop and reduced field current cause cumulative voltage fall
Speed increases rapidly
Which graph represents the hysteresis effect in the DC generator experiment?
E versus load current (IB)
E versus field current (Im) for increasing and decreasing values
Torque versus speed
Voltage versus resistance
In the experiment setup, which component measures torque produced by the DC machine?
Power Pack MV1300
Torque Measuring Unit MV1051
Resistive Load MV1100
Shunt Rheostat MV1905
