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teslafanclub

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Given a flat electrical coil of known dimentions, this coil is used as an induction coil, laid flat, on top of the cooking surface of an induction cooker. Basically, the induction cooker has a copper braided coil, and this second (external) coil is simply laid on top, made to work by inductive coupling generated by the induction cooker.

Sorry about the redundant use of "induction", but I am afraid it will get worse.

The two leads of this second flat coil are then connected to a set of incandescent lamps. The power dissipated at this "load" is 920W at 115V and 8 Amps.

Plugged into an ordinary electrical outlet (115V, 20A max), is a Watts meter, which itself is connected to the induction cooker. The induction cooker "draws" its power from the watts meter. The watts meter registers a usage of 1,280.6W (115V and 11.13A).That is a measure of what the entire circuit (induction cooker plus the watts meter, the flat coil and the load) draws from the outlet.

This means that the induction cooker (under load) has a power efficiency rating of 920W/1,280.6W = 71.8%.

It is not that great, and the power loss (in eddie currents and internal resistences) justifies using an internal fan, which itself adds to the losses. We want to improve this efficiency rating, but we are limited (the finance department holding us on a tight leash) to a minimal number of changes in design.

In order to test a few things which may increase the system's efficiency, we add another flat coil, laid on top of the aforementioned flat coil, (like stacked pankakes), which lays right on top of main induction coil of the cooker.

Yes, there are three flat coils, stacked on top of each other, two of them solely powered by Faraday's induction, while the first coil of the induction cooker is powered straight by AC.

This last coill's terminals (ends) are simply connected back to the terminals (+/-) of the set of incandescent lamps, the same way the first flat coil had been connected to them. It makes a parallel connection if you will.

By the way, the set of bulbs are, in their own layout, connected in parallel, enabling each bulb to benefit from the same voltage input from the coil(s).

Now, we are interested in finding out if the addition of that second flat coil to join the first flat coil, in powering the bulbs, will increase, decrease or not affect, the power efficiency of the system.

To recap, we have:

1) outlet -> 2) Watt meter -> 3) Induction cooker -> a flat coil on top of it, connected to a set of bulbs.

To this, we add -> an additional flat coil, which is also connected to the bulbs (hopefully to add power to it, without draining more power from the outlet).

My quizz question to you is what do you think will happen in terms of efficiency:

a) Power drawn by the entire system will increase, as the added top coil is subject to termodynamics losses, even though it might increase power output (fed to the bulbs) a bit. Basically, efficiency will DROP, because we add another coil, which has its own losses, added to the total losses (related to impedence) of the system.

b) Same input and same output. Overall efficiency remains just about the same (to the third digit or so).

c) we will GAIN efficiency, because we add a coil which is powered by the inductive coupling of the flat coil laying underneath it, which itself is powered by the induction of the cooker. A good use of inductive coupling.

Looking forward to your input.

Teslafanclub