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Hi All,
I am currently learning about AC and DC supplied coil and have been given the scenario below. I understand the first few steps but then I am unsure of how to proceed from step 3 onwards. I am very new to this so any help is much appreciated.
1. A coil is connected to a 100V DC supply and the current is of 10A. Calculate the resistance (R) of the coil.
- I Calculate this to be 10 Ohms.
2. The same coil is connected to 100V AC. Why is the current found to be 6A? Provide an explanation of why the a.c current is lower.
- When DC current flows into the coil it only offers resistance based the number of turns(N) diameter of coil (D) diameter of the wire (d) and material of the wire having resistivity (r). Whereas In AC the coils offers not only resistance but also inductive reactance. X equal to 2πFL where f is frequency of AC and L is inductance of the coil. The total impedance of coil in AC is square root of the sum of R square and X squared. The impedance is greater than R. Therefore in AC the coil draws less current.
3. If the supply voltage is 100V A.C with a period of 20ms, and the supply current (is) taken by the coil is 6A, calculate the frequency of the supply, overall impedance, inductive reactance and the inductance of the coil.
-Frequency of the supply = 50Hz
- I am unsure of how to calculate the overall impedance, inductive reactance and inductance of the coil.
4.Calculate the power factor and phase angle of the coil. (Check angle against your triangle)
5.Sketch a waveform of the voltage/current values calculated, over two complete cycles and use this to explain why the current of an R-L circuit is said to be 'out of phase' by the angle calculated.
6. Explain the relationships between voltage/current phase shifts for an R-L circuit and for an R-C circuit.
7. A capacitor is to be connected in parallel with the coil. If the capacitive reactance has the same value, in ohms, as the inductive reactance calculated above, calculate the value of capacitor required.
8. If a capacitor of a higher value is connected instead of the size calculated above, explain what would happen to the voltage/current phase relationship.
9. If the supply frequency was increased to 10^3 Hz. What would the new reactance of the capacitor from (7) above be.
TIA
I am currently learning about AC and DC supplied coil and have been given the scenario below. I understand the first few steps but then I am unsure of how to proceed from step 3 onwards. I am very new to this so any help is much appreciated.
1. A coil is connected to a 100V DC supply and the current is of 10A. Calculate the resistance (R) of the coil.
- I Calculate this to be 10 Ohms.
2. The same coil is connected to 100V AC. Why is the current found to be 6A? Provide an explanation of why the a.c current is lower.
- When DC current flows into the coil it only offers resistance based the number of turns(N) diameter of coil (D) diameter of the wire (d) and material of the wire having resistivity (r). Whereas In AC the coils offers not only resistance but also inductive reactance. X equal to 2πFL where f is frequency of AC and L is inductance of the coil. The total impedance of coil in AC is square root of the sum of R square and X squared. The impedance is greater than R. Therefore in AC the coil draws less current.
3. If the supply voltage is 100V A.C with a period of 20ms, and the supply current (is) taken by the coil is 6A, calculate the frequency of the supply, overall impedance, inductive reactance and the inductance of the coil.
-Frequency of the supply = 50Hz
- I am unsure of how to calculate the overall impedance, inductive reactance and inductance of the coil.
4.Calculate the power factor and phase angle of the coil. (Check angle against your triangle)
5.Sketch a waveform of the voltage/current values calculated, over two complete cycles and use this to explain why the current of an R-L circuit is said to be 'out of phase' by the angle calculated.
6. Explain the relationships between voltage/current phase shifts for an R-L circuit and for an R-C circuit.
7. A capacitor is to be connected in parallel with the coil. If the capacitive reactance has the same value, in ohms, as the inductive reactance calculated above, calculate the value of capacitor required.
8. If a capacitor of a higher value is connected instead of the size calculated above, explain what would happen to the voltage/current phase relationship.
9. If the supply frequency was increased to 10^3 Hz. What would the new reactance of the capacitor from (7) above be.
TIA