Voltage Across the Inductor

[Cast_Member]

Hi,

I have a problem regarding the voltage across the inductor in a series RL circuit. I have tried to apply the solution that was given to me in the text book. Here is my attempt on the question in the book:

"R=2700 Ohms, L=5.7 H & e is a 1900 V, 52Hz power supply. What is the voltage across the inductor?"

The solution:

6.28(52Hz)(5.7H)=1861.392

2700x2700+1861.392x1861.392 square root=3279

3279 Ohms/2700 Ohms tan=211.99 degrees

2700x211.99cos=-2289

2700x211.99sin=-1430

What have I done wrong? Thanks.

 

[ericgibbs]

hi,
Your total circuit impedance is correct at 3279 ohms

As you know the total impedance of the circuit, you could calculate the current thru the circuit and from that calculate the voltage across the inductor,

 

[Ratchit]

Cast_Member,

The impedance is 3279/_34.59° because arctan(1862/2700)=34.59°

The current is 1900/(3279/_34.59)=0.58/_-34.59° amps .

The voltage across the resistor is (0.58/_-34.59°)*(2700/_0°)=(1564.12/_-34.59°) volts .

The voltage across the inductor is (0.58/_-34.59°)*(1862/_90°=(1078.67/_55.41°) volts .

The sum of the phasors (1564.12/_-34.59°) and (1078.67/_55.41°) is (1900/_0°) volts .

Ratch

 

[Cast_Member]

Thanks Ratch.