6.1 KiB
Objective
The objective of this lab was to study the relationship between primary and secondary values in a single phase transformer.
Procedure
For lab 3, for each part, connect the power supply to the transformer according to the respective figure below. Then, connect the load to the opposite side of the transformer. Then measure the voltage, current, and power, using the wattmeter.
Results and Conclusions
At the end of lab 3, we showed that changing the turns ratios of the transformers changes the power out to the load, and that the load being partially reactive does pass over to the primary side of the transformer.
At the end of lab 4, we were able to calculate the internal losses of the transformer. We found the internal resistance for the core to be R_m=5760\Omega and X_m=5559\Omega. We then found the internal resistances of the transformer to be R_f=23\Omega and X_f=25.3\Omega. We also found that the efficiency of a transformer goes down as the load resistance goes up.
Wiring Diagrams
Lab 3
Figure 1: Resistive Circuit 1
Figure 2: Resistive Circuit 2
Figure 3: Resistive and Inductive Circuit 1
Figure 4: Resistive and inductive Circuit 2
Lab 4
Figure 5: Short Circuit Test
Figure 6: Open Circuit Test
Load Test
Experimental Data
Lab 3
Resistive Circuit 1
| Measurement | Value |
|---|---|
V_p |
120.17V |
V_s |
58.7V |
I_p |
0.0962A |
I_s |
0.1425A |
P_p |
11.30W |
P_s |
8.48W |
S_p |
11.56VA |
S_s |
8.36VA |
a |
\approx2.047 |
V_p,V_s,I_p,I_s,P_p,P_s\ measured\
S_p=V_p\times I_p=120.17V\times0.0962A=11.56VA\
S_s=V_s\times I_s=58.7V\times0.1425A=8.36VA\
a=\frac{V_p}{V_s}=\frac{120.17V}{58.7V}\approx2.047
Resistive Circuit 2
| Measurement | Value |
|---|---|
V_p |
120.54V |
V_s |
99.03V |
I_p |
0.234A |
I_s |
0.2414A |
P_p |
28.21W |
P_s |
24.25W |
S_p |
28.206VA |
S_s |
23.906VA |
a |
\approx1.217 |
V_p,V_s,I_p,I_s,P_p,P_s\ measured\
S_p=V_p\times I_p=120.54V\times0.234A=28.206VA\
S_s=V_s\times I_s=99.03V\times0.2414A=23.906VA\
a=\frac{V_p}{V_s}=\frac{120.54V}{99.03V}\approx1.217
Resistive and Inductive Circuit 1
| Measurement | Value |
|---|---|
V_p |
119.95V |
V_s |
58.41V |
I_p |
0.0831A |
I_s |
0.1066A |
P_p |
7.95W |
P_s |
5.19W |
S_p |
9.97VA |
S_s |
6.23VA |
a |
\approx2.054 |
V_p,V_s,I_p,I_s,P_p,P_s\ measured\
S_p=V_p\times I_p=119.95V\times0.0831A=9.97VA\
S_s=V_s\times I_s=58.41V\times0.1066A=6.23VA\
a=\frac{V_p}{V_s}=\frac{119.95V}{58.41V}\approx2.054
Resistive and Inductive Circuit 2
| Measurement | Value |
|---|---|
V_p |
119.93V |
V_s |
221.8V |
I_p |
1.138A |
I_s |
0.417A |
P_p |
97.9W |
P_s |
77.3W |
S_p |
136.48VA |
S_s |
92.49VA |
a |
\approx0.54 |
V_p,V_s,I_p,I_s,P_p,P_s\ measured\
S_p=V_p\times I_p=119.93V\times1.138A=136.48VA\
S_s=V_s\times I_s=221.8V\times0.417A=92.49VA\
a=\frac{V_p}{V_s}=\frac{119.93V}{221.8V}\approx0.54
Lab 4
Short Circuit Test
| % | I_H\ (A) |
V_H\ (V) |
P_H\ (W) |
|---|---|---|---|
25 |
0.125 |
4.26 |
0.362 |
50 |
0.25 |
8.59 |
1.463 |
75 |
0.375 |
12.73 |
3.17 |
90 |
0.45 |
15.25 |
4.63 |
100 |
0.5 |
17.09 |
5.75 |
All values measured
R_f={P\over I^2}={5.75W\over0.5A^2}\R_f=23\Omega\
X_f=\sqrt{({V\over I})^2- ({P\over I^2})^2}= \sqrt{({17.09V\over 0.5A})^2- ({5.75W\over0.5A^2})^2}\
X_f=25.3\Omega
Open Circuit Test
| % | V_L\ (V) |
I_L\ (A) |
P_L\ (W) |
|---|---|---|---|
25 |
15 |
0.0227 |
0.248 |
50 |
30 |
0.0339 |
0.771 |
75 |
45 |
0.0458 |
1.576 |
100 |
60 |
0.0600 |
2.50 |
125 |
75 |
0.0829 |
3.92 |
All values measured
R_m=a^2{V_s^2\over P}= 4({60V^2\over2.5W})\R_m=5760\Omega\
X_m={V^2\over\sqrt{(VI)^2-P^2}}={60V^2\over\sqrt{(60V\times0.06A)^2-2.5W^2}}\
X_m=5559\Omega
Load Test
R_L |
I_H(A) |
V_H(V) |
P_H(W) |
I_L(A) |
V_{L_{NL}}(V) |
V_{L_{FL}}(V) |
P_L(W) |
Eff | % Reg |
|---|---|---|---|---|---|---|---|---|---|
1200 |
0.0517 |
120 |
5.49 |
0.0492 |
59.3 |
59.6 |
2.8 |
51.0\% |
0.50 |
600 |
0.0719 |
120 |
8.31 |
0.0951 |
59.1 |
59.6 |
5.67 |
68.2\% |
0.84 |
400 |
0.0954 |
120 |
11.20 |
0.1428 |
58.7 |
59.6 |
8.48 |
75.7\% |
1.51 |
300 |
0.1234 |
120 |
14.62 |
0.1996 |
58.6 |
59.6 |
11.79 |
80.6\% |
1.68 |
240 |
0.1470 |
120 |
17.43 |
0.2463 |
58.3 |
59.6 |
14.50 |
83.2\% |
2.18 |
200 |
0.1688 |
120 |
20.04 |
0.2903 |
57.9 |
59.6 |
16.98 |
84.7\% |
2.85 |
eff(%)=\frac{P_L}{P_H}=\frac{2.8}{5.49}\approx51.0%\
%\ reg = \frac{V_{L_{NL}-V_{L_{FL}}}}{V_{L_{FL}}}=\frac{59.3-59.6}{59.6}=0.50%