So I have the circuit below and this is the information given:
Load 1 absorbs 4203.22-2835.11j [VA]
Voltage sources delivers 7500 [W]
v_s(t) = 400cos(100[rad/s]t+38°) [V]
Find all possible values for L_A
So my idea was to put it into phasor domain.
So V_s=400<38°
Since the voltage source only delivers power the angle of voltage and current have to be the same since the power factor is 1 so I came up with
S_L=.5(V_s)(I_L*) (Complex Power Formula)
So I_L=(7500/400*2)<38° = 37.5<38°
Then I could find the voltage of the Load and that comes out to be
Using S_L=.5(V_L)(I_L*)
V_L= 2*(4203.2-2835.1j)/(37.5<38°)
V_L= 269.744+18.86j
After that i thought I could just do a KVL to get the value for L_A (the inductor)
So KVL
-V_s+(L_A+R_1)(I_L)+V_L=0
So I get
-400<38°+37.5<38°(100LjΩ+3.3Ω)+ 269.744+18.86j = 0
But this does not give me a real value for L_A, I am getting a complex value
For reference the answer is 77.1 [mH]
Load 1 absorbs 4203.22-2835.11j [VA]
Voltage sources delivers 7500 [W]
v_s(t) = 400cos(100[rad/s]t+38°) [V]
Find all possible values for L_A
So my idea was to put it into phasor domain.
So V_s=400<38°
Since the voltage source only delivers power the angle of voltage and current have to be the same since the power factor is 1 so I came up with
S_L=.5(V_s)(I_L*) (Complex Power Formula)
So I_L=(7500/400*2)<38° = 37.5<38°
Then I could find the voltage of the Load and that comes out to be
Using S_L=.5(V_L)(I_L*)
V_L= 2*(4203.2-2835.1j)/(37.5<38°)
V_L= 269.744+18.86j
After that i thought I could just do a KVL to get the value for L_A (the inductor)
So KVL
-V_s+(L_A+R_1)(I_L)+V_L=0
So I get
-400<38°+37.5<38°(100LjΩ+3.3Ω)+ 269.744+18.86j = 0
But this does not give me a real value for L_A, I am getting a complex value
For reference the answer is 77.1 [mH]
Attachments
-
6.6 KB Views: 22