[TCML] Motivation for grounding the Tesla coil secondary

[chris <spamsandwich@xxxxxxxxxx>]

What people have said about the RF ground is correct; anything somewhat
bigger than the top load is fine for resonant currents.

I guess another motivation to have a independent secondary ground is
safety; the primary coil is often associated strongly with the mains
power line or something even worse in DC-fed SSTCs. 

In case of primary-secondary flash-over at the base, someone touching
the top load with their fluorescent lamp and beer in hand may enjoy a
fatal electric shock. 

Here in Europe where we get 400V poly-phase mains in modern buildings.
Americans are probably less worried by their puny 110V system.

We also have apartment buildings poorly suited to Tesla coil operation
due to neighbors who write polite letters to the property manager when
you make their alarm clock emit smoke. 

Earthing is also about EMI control.

It's worth establishing an RF ground plane (which talks to the rebar
through the parquet) to which all low frequency circuits in the E-field
zone are coupled using standard mains power line filters blocks.

The Y2 safety capacitors in these filters carry RF current pretty well. 

Connect the capacitive side of the filter to the RF plane. The inductive
port of the power filter best goes towards a 1:1 mains isolating
transformer kept on a longish cable, living well outside the E-field
range. The common-mode choke might help here with conducted EMI if it's
not saturated yet.

Surge robust resistors provide a weak leakage path from the RF ground
back to the Protective Earth (or even the Live/Neutral) to avoid charge
accumulation on the RF plane. 

Big ceramic resistors (e.g. 100K) politely and safely "warn" you not be
too casual about touching stuff when poking about with an oscilloscope. 

It's practical not to use the PE conductor at the wall at all.


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