Hello all,
We've been given some questions related to DC Machines and I'm not entirely if what I've come up with so far makes any sense.
Here are the questions,
1) Why is the armature current non-zero even when there is no load on the shaft of the machine?
2) Why does the armature current slightly increase although the shaft load remains constant?
3) Explain a practical strategy for speed control of a DC machine when both terminal voltage and field current are available for control.
Here are my thoughts on the answers,
1) It is because Ea = Vt + IaRa, Since Ea is non-zero and Vt=0, Ia must be nonzero?
2) I'm not entirely sure, can someone explain?
3) The speed relates to Ea, which can be controlled by means of Vt and If through the following equations,
Ea = Vt + IaRa
If we ignore magnetic non linearity the flux will be proprtional to the field current. Thus,
Ea = k'Ifω
Is there a better explanation/way to the answer the following questions?
I look forward to your input.
We've been given some questions related to DC Machines and I'm not entirely if what I've come up with so far makes any sense.
Here are the questions,
1) Why is the armature current non-zero even when there is no load on the shaft of the machine?
2) Why does the armature current slightly increase although the shaft load remains constant?
3) Explain a practical strategy for speed control of a DC machine when both terminal voltage and field current are available for control.
Here are my thoughts on the answers,
1) It is because Ea = Vt + IaRa, Since Ea is non-zero and Vt=0, Ia must be nonzero?
2) I'm not entirely sure, can someone explain?
3) The speed relates to Ea, which can be controlled by means of Vt and If through the following equations,
Ea = Vt + IaRa
If we ignore magnetic non linearity the flux will be proprtional to the field current. Thus,
Ea = k'Ifω
Is there a better explanation/way to the answer the following questions?
I look forward to your input.