Recent content by acw260

For z11 assume that the input is not open circuit. Therefore I1 is not equal to zero. I1 then cancels out from the equation leaving z11 = R8+R6. You don't need a value for I1, just that it doesn't equal zero. For z12 again it doesn't matter what value you have for I2. You show that z12 = R6 =...

Please see the attachment for the problem in its original format, which should make things clearer. I have solved the derivation of equation 5(a). I can solve the derivation of equation 5(b) no problem using "V=IX" (ignoring the resistance of the cables for the purposes of the fault...

Homework Statement Given the relationships: Xpu = MVAbase / MVAfault Xpu = ( MVAbase / MVArated ) * ( X% / 100 ) MVAfault = sqrt(3) * V * Ifault Xohms = [ V / sqrt(3) ] * Ifault Homework Equations Show that: Xpu = [ MVAbase / V^2 ] * Xohms The Attempt at a Solution No matter how I...

Thanks for taking the time to look at this for me guys. This set of questions had been frying my brain for over a week. Your nudges in the right direction are very much appreciated.

For the answer to Q(2) I've now found two independent texts giving the solution as V=IR(1-e^(-t/CR) where the initially open circuit with a discharged capacitor is subject to a step change in circuit current. (I've removed the confusing subscripts, but V is still the voltage across the load and...

Ok, derivation of the answer to Q(1) as follows: Vin = Ip * Req where Vin is the input voltage; Ip is the source current (from the piezoelectric crystal); Req is the equivalent resistance of the parallel capacitor and load In the s-domain: Vin(s) = Ip(s) * Req(s) therefore Vin(s) / Ip(s) =...

Apologies, the formatting here has confused things by changing subscripts to capitals. 'vL' is voltage across the load (the L should be subscript) 'iP' is the circuit current from piezoelectric crystal / norton generator (the P should be subscript). Neither 'L' nor 'P' are variables in the...

I've copied the delta symbol exactly as it appears in the text of the question I've been set. I've taken it to simply mean 'change in' (voltage or current in this scenario). The three values for CC, CP and RL listed immediately above the subtitle 'TABLE A' are the values from TABLE A as they...

Homework Statement An accelerometer is connected via a length of coaxial cable to an amplifier. The arrangement is modeled by: (a) a Norton generator in parallel with a capacitor (CP) representing the piezoelectric crystal within the accelerometer; (b) a lumped capacitor (CC) representing...

Ok, I can see that I've manipulated the given formula incorrectly for (b). Second attempt: Zin = Zo [ ( (ZL COS βℓ) + (jZo SIN βℓ) ) / ( (Zo COS βℓ) + (jZL SIN βℓ) ) ] = 50 x [ ( (40+j30)COS(0.8π) + (j50)SIN(0.8π) ) / ( 50COS(0.8π) + j(40+j30)SIN(0.8π) ) ] = 25.47 + j5.9 How does this look?

Thanks BvU, I shall do just that!

Homework Statement (a) A transmission line has a length, ℓ, of 0.4λ. Determine the phase change, βℓ, that occurs down the line. (b) A 50Ω lossless transmission line of length 0.4λ is terminated in a load of (40 + j30) Ω. Determine, using the equation given below, the input impedance to the...

Homework Statement Homework Equations As above. The Attempt at a Solution (z11) With the output open circuit (and therefore I2=0) z11 = V1 / I1 = (R8 + R6)I1 / I1 = 14ohms; (z12) With the input open circuit (and therefore I1=0) z12 = V1 / I2 = R6 = 6ohms; (z21) With the output...