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Frequently Asked Questions
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| Series Transformers |
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| 9. |
Q: |
Your specifications say “Full load primary power factor is better than 0.97 in all cases”. Does this apply to all CCR steps? Also, when a bulb burns out (transformer open circuit), what are the power factors at all steps?
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A: |
The simple answers to your questions are:
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A transformer with a pure resistive load, such as an incandescent bulb, has a power factor very close to 1, at all CCR steps. |
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An open circuit transformer is almost a perfect inductance, so the power factor is very close to zero, at all CCR steps. |
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The following are actual measurements (using sine waves) made at Amerace
August 15, 2000. |
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Transformer type: TAG045665 45W, 6,6/6,6A, 50 Hz
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Design Load |
Open Circuit |
| Pr. Current |
PF |
Phase Angle |
PF |
Phase Angle |
| 2.8 |
0.997 |
4° |
0.085 |
85° |
| 3.4 |
0.997 |
4° |
0.077 |
86° |
| 4.1 |
0.997 |
4° |
0.076 |
86° |
| 4.8 |
0.997 |
4° |
0.076 |
86° |
| 5.2 |
0.997 |
4° |
0.079 |
85° |
| 5.5 |
0.997 |
4° |
0.080 |
85° |
| 6.6 |
0.997 |
4° |
0.084 |
85° |
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Transformer type: TA10066D 100W, 6,6/6,6A, 50 Hz
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Design Load |
Open Circuit |
| Pr. Current |
PF |
Phase Angle |
PF |
Phase Angle |
| 2.8 |
0.996 |
5° |
0.069 |
86° |
| 3.4 |
0.996 |
5° |
0.064 |
86° |
| 4.1 |
0.996 |
5° |
0.062 |
87° |
| 4.8 |
0.996 |
5° |
0.060 |
87° |
| 5.2 |
0.996 |
5° |
0.063 |
87° |
| 5.5 |
0.996 |
5° |
0.061 |
87° |
| 6.6 |
0.996 |
5° |
0.063 |
87° |
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Transformer type: TA150665 150W, 6,6/6,6A, 50 Hz
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Design Load |
Open Circuit |
| Pr. Current |
PF |
Phase Angle |
PF |
Phase Angle |
| 2.8 |
0.996 |
5° |
0.069 |
86° |
| 3.4 |
0.996 |
5° |
0.063 |
86° |
| 4.1 |
0.996 |
5° |
0.060 |
87° |
| 4.8 |
0.996 |
5° |
0.057 |
87° |
| 5.2 |
0.996 |
5° |
0.056 |
87° |
| 5.5 |
0.996 |
5° |
0.056 |
87° |
| 6.6 |
0.996 |
5° |
0.057 |
87° |
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