# Current Limiting and Impedence

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• Subject: Current Limiting and Impedence
• From: "Tesla list" <tesla@xxxxxxxxxx>
• Date: Thu, 21 Apr 2005 09:56:09 -0600
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• Resent-date: Thu, 21 Apr 2005 09:58:43 -0600 (MDT)
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`Original poster: "Mark Dunn" <mdunn@xxxxxxxxxxxx>`

`All:`

`Please follow my math and explain my confusion.`

```My TC power transformers have an impedence Z = 1.2 Ohms(secondary
shorted).```

```I built a Current Limiting Inductor(CLI) with L = 15 mH, thus at 60Hz
X = 2*Pi*60*.015 = 5.65 Ohms. The R for the CLI is negligible. So the
inductor Z = 5.65 Ohms. The system therefore has total impedence of Z =
5.65 + 1.2 = 6.85 Ohms.```

```This limits current to 120 VAC/6.85 Ohms = 17.5 amps.
I have confirmed this through testing.```

```Measuring voltage BETWEEN the inductor and transformer I get around 90
to 100 volts(Mains 120V). So if I break down the circuit and consider
the current the individual components...
Transformer I = 90 VAC /1.2 ohms = 75 amps
CLI   I = 30 VAC /5.65 Ohms = 5.3 amps```

```Obviously, one can't analyze the components this way.  Is it because the
voltage measurements are not accurate due to the phase angle?  Am I not
allowed to analyze individual component impedence?  What don't I
understand.```

Thanks.
Mark