Transformers Sample Assignment

Transformers

1. The turns ratio modified to 20:1, calculate the following values of Vs and Is for the given values of RLin the table below:

Transformers img1 Transformers img2 Transformers img3 Transformers img4 Transformers img5 Transformers img6

RL

Calculated Vs

Calculated Is

Measured Vs

Measured Is

0 Ω

120Vrms/20:1 = 6Vrms

6Vrms/0ohms= 0A

05.99Vac

-r-

10 Ω

120Vrms/20:1 = 6Vrms

6Vrms/10ohms= 600mA

05.99Vac

599.97mA

25 Ω

120Vrms/20:1 = 6Vrms

6Vrms/25ohms= 240mA

05.99Vac

239.991mA

50 Ω

120Vrms/20:1 = 6Vrms

6Vrms/50ohms= 120mA

05.99Vac

119.995mA

100 Ω

120Vrms/20:1 = 6Vrms

6Vrms/100ohms= 60mA

05.99Vac

59.998mA

1000 Ω

120Vrms/20:1 = 6Vrms

6Vrms/1000ohms= 6mA

05.99Vac

6mA

2. Construct the transformer circuit in MultiSIM and complete the table in part 2 with the measured values of Vs and Is for each value of RLUse the Agilent Digital Multi-meter to take the measurements and capture a screen shot of each measurement.

3. Discuss the following:

Transformers img7 Transformers img8 Transformers img9 Transformers img10 Transformers img11 Transformers img12
  • Describe the relationship of RLon the secondary voltage.

The secondary voltage equals RL times Is.

  1. Describe the relationship of RLon the secondary current.

    The secondary current equals secondary voltage divided by RL

  2. How do the calculated values compare to the measured values?

    Yes, although I can get a 0A when resistor equals 0 but when measuring I get –r- or overload reading.  Np/Ns = Vp/Vs.

  3. How would you go about calculating the transformer power efficiency?

    Efficiency = (Vs*Is)/(Vp*Ip)

  4. How would you go about measuring the transformer power efficiency?

    Put 2 wattmeter on both ends of the transformer (on the primary and on the secondary). Divide the output of power of primary by the input power of the secondary.

  5. Determine the transformer power efficiency for the circuit in MultiSIM. Include a calculation and a measured value. Transformers img13

    Efficiency = (Vs*Is)/(Vp*Ip)= (5.99*0.599)/(120*0.030) = (3.58/3.60)

    = 99.44% 

Include all calculations, screenshots of measurements, the table results of part 2 and the answers to part 4 in a word processing document and submit as EE115W4LabYourGID.docx, or an equivalent word processing file extension.