The raw physics of current flow are not brought up to field electricians.
It is the domain of Physics professors, though.
I can't recommend Feynman's Lectures on Physics too highly.
He crams the better part of a semester into one lecture: 22 -- pages 22-1 through 22-18.
The right-angle impedence is a result of Maxwell's Equations. Lecture 20 -- pages 20-1 through 20-15.
The simplest way I can put it:
Imagine it's a DC flow of current... that's going in one straight direction. Around that flow a saturated magnetic field has been established.
Next, the DC current takes a right angle turn. The magnetic field HAS to turn to stay oriented around the DC flow. It's now in a different direction.
DC will only affect the CT for the very few first seconds -- as the field is being built up.
(DC does actually have impedance. All of the world's computers utterly depend on it to function. It's just that it tails off to pure resistance at all ordinary reaction times. And it's simpler to explain to the newbies that way.)
Now imagine that the DC is AC. A field that was vectored in direction alpha now is turned into direction beta. The CT measures CHANGES IN FIELD INTENSITY. It's as if you have just pushed a field compass around the circuit. You bet the needle moves. (For our example, think of AC as instantaneous DC.)
The current in the CT doesn't care WHAT the field intensity did -- up, down or flat, if it CHANGED then a wave form was induced into the CT conductor and core.
The twisting of the E & B fields obeys the right hand rule and a bunch of thick calculus equations. For field wiring, these issues are entirely neglected.
They only come up when you're pushing your luck: massive current flows, very close distances (inverse square law applies) and voltage amplification. (it's a CT)
CTs don't push a lot of current, but they do have the potential to really pump up the voltage. If you're unlucky enough to have a CT crossing two -- out of phase AC conductors -- then its own (higher voltage) secondary is going to be seeing currents it's not designed to carry.
QED.
I leave it to the readership to troll the Internet on this issue.
Suffice it to say that all surge protectors come with instructions -- that tell the installer to eliminate every possible bend in the conductors -- PARTICULARLY sharp right angle bends. This is because EACH and EVERY such turn is a locus of impedance. (per the laws of electromagnetism) If carried too far, during a lightning event, you can break down the equipotential voltage plane and cause shocks to all and every. This happens at the speed of light.
The sole reason for this specific instruction is because my assertion is correct. You don't need to coil a conductor to get an inductor effect. Even a quarter turn has an impedence effect. Yes, it's been proven in test labs -- going back forever.
Lastly, E-mon may have incorporated EM shielding in their gadget. It would cost them peanuts. All that's required is a thin metallic outer layer that's encapsulated in plastic along with the rest of the gadget. The only field that would influence their CT would be the one at the core.
The CT in question, plainly, does NOT have any shielding.
Last edited by Tesla; 02/10/14 01:02 AM.
