TCBA Volume 15 - Issue 1
Page 9 of 18
Capacitive Reactance Chart
Values from .01uF to .1uF.
X/C only for 60 Hertz
Shown on this chart are some popular utility distribution voltages.
| CAP uF | Xc Ohms | 4200 Volts | 7200 Volts | 12000 Volts | 14400 Volts | ||||
|---|---|---|---|---|---|---|---|---|---|
| mA | VA | mA | VA | mA | VA | mA | VA | ||
| .01 | 265,258 | 15.8 | 67 | 27.1 | 195 | 45 | 543 | 54.3 | 782 |
| .02 | 132,629 | 31.7 | 133 | 54.3 | 391 | 91 | 1086 | 109 | 1564 |
| .03 | 88,419 | 47.5 | 200 | 81.4 | 586 | 136 | 1629 | 163 | 2345 |
| .04 | 66,316 | 63.3 | 266 | 109 | 782 | 181 | 2172 | 217 | 3127 |
| .05 | 53,052 | 79.2 | 333 | 136 | 977 | 226 | 2714 | 271 | 3909 |
| .06 | 44,210 | 95 | 399 | 162 | 1173 | 271 | 3257 | 326 | 4690 |
| .07 | 37,894 | 111 | 466 | 190 | 1368 | 317 | 3800 | 380 | 5472 |
| .08 | 33,157 | 127 | 532 | 217 | 1564 | 362 | 4343 | 434 | 6254 |
| .09 | 29,473 | 143 | 599 | 244 | 1759 | 407 | 4886 | 489 | 7036 |
| .10 | 26,526 | 158 | 665 | 271 | 1954 | 452 | 5429 | 543 | 7817 |
Shown below are other usable voltages often encountered.
| CAP uF | Xc Ohms | 5000 Volts | 10000 Volts | 15000 Volts | 20000 Volts | ||||
|---|---|---|---|---|---|---|---|---|---|
| mA | VA | mA | VA | mA | VA | mA | VA | ||
| .01 | 265,258 | 18.9 | 94 | 37.7 | 377 | 56.6 | 848 | 75.4 | 1508 |
| .02 | 132,629 | 37.7 | 189 | 75.4 | 754 | 113 | 1697 | 151 | 3016 |
| .03 | 88,419 | 56.6 | 283 | 113 | 1131 | 170 | 2545 | 226 | 4524 |
| .04 | 66,316 | 75.4 | 377 | 151 | 1508 | 226 | 3393 | 302 | 6034 |
| .05 | 53,052 | 94.3 | 471 | 189 | 1885 | 283 | 4241 | 377 | 7540 |
| .06 | 44,210 | 113 | 566 | 226 | 2262 | 339 | 5089 | 452 | 9048 |
| .07 | 37,894 | 132 | 660 | 263 | 2639 | 396 | 5937 | 527 | 10556 |
| .08 | 33,157 | 151 | 754 | 302 | 3016 | 452 | 6786 | 603 | 12064 |
| .09 | 29,473 | 170 | 848 | 339 | 3393 | 509 | 7634 | 679 | 13572 |
| .10 | 26,526 | 188 | 943 | 377 | 3770 | 565 | 8482 | 754 | 15080 |
The above numbers are provided for reference only as spark gap inefficiencies and other losses will tend to increase the total VA burden of the power supply transformer. Note that when you double the supply voltage, the VA burden increases four times in magnitude! Since excessive current can destroy a transformer, particular attention should be paid to the size (in microfarads) of the capacitor selected so that its value does not exceed the rating of the supply transformer. The numbers were calculated from standard AC and Ohms Law formulas. Good luck and happy winding!
Henry Hurrass
PO Box 82725
Phx. AZ 85071
capchart.wps