Design of Electrical Machines Questions and Answers – Motor Starters, Calculation of Resistance Steps & Design of Field Regulators

This set of Design of Electrical Machines test focuses on “Motor Starters, Calculation of Resistance Steps & Design of Field Regulators”.

1. What is the function of the motor starter with respect to current?
a) to slow the low current flow
b) to prevent the low current flow
c) to allow the large current flow
d) to prevent the large current flow
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2. What is the work of the starter with respect to the mechanical stress?
a) to allow large mechanical stress
b) to restrict large mechanical stress
c) to allow small mechanical stress
d) to restrict small mechanical stress
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3. What is the relation of the current with the starting torque in the starter concept?
a) the starter should restrict current to prevent low starting torque
b) the starter should restrict current to produce high starting torque
c) the starter should send current to prevent low starting torque
d) the starter should send current to produce high starting torque
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4. When does the starter take up liquid rheostat?
a) when the resistance can be varied heavily
b) when the resistance can be varied gradually
c) when the resistance cannot be varied
d) when the resistance should not be varied
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5. The starter take up metallic resistance when the resistance should not be varied in steps.
a) true
b) false
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6. What happens when the starter takes up metallic resistance?
a) voltage fluctuates from high to low
b) voltage fluctuates between fixed upper and lower limits
c) current fluctuates from high to low
d) current fluctuates between fixed upper and lower limits
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7. What is the product of the ratio of the current and the useful flux per pole?
a) product of ratio of current and useful per pole = (useful flux per pole due to upper limit current * upper limit current) / (useful flux per pole due to lower limit current * lower limit current)
b) product of ratio of current and useful per pole = (useful flux per pole due to upper limit current + upper limit current) / (useful flux per pole due to lower limit current + lower limit current)
c) product of ratio of current and useful per pole = (useful flux per pole due to upper limit current – upper limit current) / (useful flux per pole due to lower limit current – lower limit current)
d) product of ratio of current and useful per pole = (useful flux per pole due to upper limit current * lower limit current) / (useful flux per pole due to lower limit current * upper limit current)
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8. How many machines are considered in the calculation of the resistance steps?
a) 2
b) 3
c) 4
d) 5
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9. What is the concept of notching operation?
a) process of decreasing the voltage
b) process of increasing the efficiency
c) process of cutting out the resistance
d) process of adding on the resistance
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10. What happens in the dc shunt motor when the notching process occurs?
a) flux remains constant
b) speed remains constant
c) voltage remains constant
d) current remains constant
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11. What is the formula of the ratio of the lower limit to upper limit of current with respect to the resistance?
a) lower limit of current / upper limit of current = motor resistance / resistance to limit the starting current
b) lower limit of current / upper limit of current = (motor resistance / resistance to limit the starting current)^{1/number of resistance}
c) lower limit of current / upper limit of current = (motor resistance * resistance to limit the starting current)^{1/number of resistance}
d) lower limit of current / upper limit of current = motor resistance * resistance to limit the starting current
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12. What is the relation of the ratio of rotor current limits and the ratio of lower limit to upper limit current?
a) ratio of rotor current limits = ratio of lower limit to upper limit current
b) ratio of rotor current limits > ratio of lower limit to upper limit current
c) ratio of rotor current limits < ratio of lower limit to upper limit current
d) no relation between ratio of rotor current limits and ratio of lower limit to upper limit current
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13. How many machines are considered for the design of field regulators for dc machines?
a) 2
b) 3
c) 4
d) 5
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14. What is the first step in the design of the field regulators for dc machines?
a) calculation of the resistance of section
b) calculation of the total field circuit resistance
c) calculation of the field circuit resistance
d) resistance to be inserted
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15. What is the second step in the design of the field regulators for dc machines?
a) calculation of the resistance of section
b) calculation of the total field circuit resistance
c) calculation of the field circuit resistance
d) resistance to be inserted
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16. What is the last step involved in the design of field regulators for shunt generators?
a) calculation of the resistance of section
b) calculation of the total field circuit resistance
c) calculation of resistance of section
d) resistance to be inserted
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17. What is the first step in the design of the field regulators for dc motor?
a) number of sections
b) shunt field circuit resistance
c) shunt field resistance
d) resistance of step
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18. What is the plot of the magnetization curve?
a) field current in the y axis vs voltage in x axis
b) field current in the x axis vs voltage in y axis
c) armature current in the y axis vs voltage in x axis
d) armature current in the x axis vs voltage in y axis
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