#low impedance

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Lustraphone VR/53 L ribbon microphone

[fenceblog]

What Is a Low Impedance Fence Charger?

The term "low impedance" may sound like electrical jargon, but at heart the concept’s really simple. If an electric fence line already has an electric charge on it, that makes it harder to add more charge to the line. So if one can momentarily reduce the charge being carried, that makes it easier for a new charge to power up the line.

Modern low impedance electric fence chargers aren’t like the old “weed-burners” that put out a continual charge. Instead they put out a charge that lasts for a brief instant (say a few thousandths of a second), after which they put out nothing for the rest of the cycle (say about a second), after which the cycle is repeated. This allows the charge to be reduced by various power drains (weeds, brush or imperfect connections such as are commonly found on electric fences). And so the next charge, coming at the start of the next cycle, has an easy time moving outward on the electric fence line—because there is little existing charge ("low impedance") on the line.

Today nearly all electric fence chargers are low impedance chargers. (If your charger sports a flashing light you can count on it being a low impedance charger.) That’s because these pulsed chargers have real advantages. They use very little power. They are safer than the old weed-burners because a shocked animal or person can let go of the fence between the pulses. And they are less likely to start fires. Even so, marketers don’t like talking about the charge being "reduced" or "absent" from the line, even for a moment—so they have resorted to obfuscation—using the technical term “low impedance” to describe their products, figuring rightly that this is a term few but electricians will understand.