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Using a big TC on stage? Australia's Got Talent

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LAN_403

Tesladownunder

Mon Jan 31 2011, 07:54PM

Registered Member #10 Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424

I was invited to enterAustralia's Got Talent. Suzanne (exec. producer) brought a cameraman came to do some preliminary video at my place on November 24, 2010. I was looked up specifically due to the top 5 success of "Arc Attack" in the American equivalent show which Suzanne had seen first hand.

I've just found that I have made it to the televised heats in March 20th in the Perth Convention and Entertainment Center. Still big hurdles re venue, power, earthing, preventing interference and public liability.

So, my question is whether anyone here has practical information about stage performances? My big concern is damage to stage equipment and counterpoise earthing.

Coronafix

Mon Jan 31 2011, 08:20PM

Registered Member #160 Joined: Mon Feb 13 2006, 02:07AM
Location: Melbourne, Australia
Posts: 938

Fabio would be the person to ask.

Martin King

Mon Jan 31 2011, 09:34PM

Registered Member #3040 Joined: Tue Jul 27 2010, 03:15PM
Location: South of London. UK
Posts: 237

I would say allow PLENTY of time for tests in situ with as much of the tech. equipment that will be there on the night in place as possible. I was working at a gig quite a few years ago where a Tesla coil was supposed to be used live on stage with an orchestra however it seems they could not overcome interference issues to the PA and so had to pull the coil from the gig. Lots of lost money and red faces !

Martin.

Dr. Drone

Wed Feb 02 2011, 12:49AM

Registered Member #290 Joined: Mon Mar 06 2006, 08:24PM
Location:
Posts: 1673

Fabio

Sun Feb 06 2011, 12:40AM

Registered Member #122 Joined: Fri Feb 10 2006, 12:55PM
Location: Milano Italy
Posts: 148

First of all, try to get more testing time with lights, cameras, microphones and all electronic equipment in place before starting rehearsals for the show, 2-3 days are usually enough.

second, double check that every metallic structure is properly grounded, the standard long cable connected to the main grounding is OK for safety reasons but may not suffice for RF/EMI shielding; for this purposes every structure must be connected with all other structures in the vicinity with big and short cables (do not remove the existent safety ground, just add your ground!)

supervise the installation of all equipment, you easily be able to find if a microphone, a camera or a cable is installed too close to a coil and ask for his reallocation.... if an a reallocation isn't possible, pretend the use of a fully wireless device (even battery powered), try to protect them with a faraday cage and inform of the danger of his destruction......... AN HIGH VOLTAGE SPIKE INCIDENTALLY CONDUCTED IN A SIGNAL CABLE CAN CAUSE AN ENORMOUS FAILURE OF ALMOST ALL ELECTRONIC EQUIPMENTS!!!!!

also check for the cable routing, their cables must pass away from your equipments and your cables must pass away from their cables and their equipments.
you can probably cause some disturbs on the lighting system because this is the most confused part of the entire setup, there will be an huge mess of cables, splittings, rolls of partially used cables tangled somewhere, many ground loops and a delicate serial cable that connecting in cascade every fixture (DMX 512).
you must take care that every ground loop must be shorter as possible, otherwise all lights will literaly play for himself when your coil is switched ON

for legal issues you cannot connect your equipment to the power grid....... in many occasion even their equipments can be connected to the mains...... they usually use one or more enormous truck- mounted gasoline generators to overcome some law restrictions.
Ask for a smaller generator exclusively reserved for your coils to be totally isolated from the mains and from their equipments (will have no problem to provide a small generator..... uhmmmm, sometimes may have some trouble to provide a little one, once "we had to settle" for a 500kW truck-mounted generator for powering only 3400 watts!!!!)

Ciao!
Fabio.

Microwatt

Thu Feb 17 2011, 06:57PM

Registered Member #3282 Joined: Wed Oct 06 2010, 05:01PM
Location:
Posts: 224

Fabio wrote ...
once "we had to settle" for a 500kW truck-mounted generator for powering only 3400 watts!!!!)

Ciao!
Fabio.

Just imagine if you could build a TC that could take that kind of power.

Tesladownunder

Sun Feb 20 2011, 04:52AM

Registered Member #10 Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424

Thanks for everyones comments including Fabio and Joe DiPalma from Arc Attack. Also Dr Spark and Martin King.

The powers that be have decided to run me outdoors rather than on a stage. Certainly easier for me as I won't have to Faraday cage stuff and now have all day for testing and setup.

There is no car access here and no place a generator can even come close. Other downsides are the need for darkness and possiblility of being washed out by rain. By the end of the day Judges are likely to be tired and grumpy too!
I will need to use the available power which is 415 V 3 phase (=250V per leg) 32A. My TC normally runs up to 75A (18kW) (remarkably, this is the first time ever I have measured it!). so I have a problem limiting current so I won't pop the breaker during a show. I can only use one phase so am limited to

I plan to use an isolating transformer which will also act as a ballast. The quickest solution I could think of was to run a number of small arc welders back to back.
The advantages of this are;
1 a 130A arc welder is only $100 and will handle peak inputs of around 15A at 250V. Run back to back with another arc welder it will give perhaps 10A out the other end allowing for inefficiencies per pair of welders. Run 4 welders gives perhaps 20A and 6 will give 30A, adjustable.
2 The small welders can be handled separately rather than a single larger transformer.
3 It makes me "legal" from a wiring point of view. All power will be dropped to 50V AC which is where the electrical authorities jurisdiction ends (sort of). Wiring up to that point will be as purchased or electrician wired.
4 Residual current devices should not be tripped.
So for $600 I have portable current limiting, am legal, won't trip an RCD and should prevent a lot of nasties going through to the Convention Center.
Call it a MMW (multi-mini-welder unit).

1298176986 10 FT107519 Agtpositionoftc 2

Note that this lawn and trees are above a large underground carpark. When is a ground not a ground?

1298176986 10 FT107519 Agtpoweroutlet3phase

Fabio

Sun Feb 20 2011, 10:40PM

Registered Member #122 Joined: Fri Feb 10 2006, 12:55PM
Location: Milano Italy
Posts: 148

Hi All!

I will need to use the available power which is 415 V 3 phase (=250V per leg) 32A. My TC normally runs up to 75A (18kW) (remarkably, this is the first time ever I have measured it!). so I have a problem limiting current so I won't pop the breaker during a show. I can only use one phase so am limited to

you can use a 415-250 step-down isolation transformer for getting more power on a single phase, you can also use some 415V arc welders for the first stage and some 250V arc welders for the second stage to get more power without breaking the australian laws!

Note that this lawn and trees are above a large underground carpark. When is a ground not a ground?

you can use some earth rods buried close to the coil and some other ones buried away from the carpark; if the soil outside the coil is too thin, you can dampen it to reduce his resistance

Ciao!
Fabio.

CokeCanNinja

Mon Feb 21 2011, 04:25AM

Registered Member #3706 Joined: Mon Feb 21 2011, 04:17AM
Location:
Posts: 11

If possible (and this is a long shot) put everything in Faraday cages.

Tesladownunder

Thu Apr 14 2011, 01:05PM

Registered Member #10 Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424

I did the show for the first heats of the TV show "Australia's Got Talent" with my 18 inch TC and 7-8 foot hot sparks.
It was done in a massive pavilion with a 50 foot ceiling. The crowd, judges and all the video cameras were behind plastic barriers. After much consideration on the day, I finally decided to go with a 9 foot high metal frame surround with down wires at intervals. The concrete floor was covered for 20 - 30 m with builders foil with multiple links to the TC earth and framework. There was no direct link to the pavilion building earth but there may have been through some expansion joint covers. The mains earth was kept separate.
I ran the ARSG gap and blower gap motors through back to back arc welders as isolation transformers. There was no clear return path for capacitative currents induced into the 50 foot ceiling. There was no ground available for over 100 m that was not a mains ground.
Using this method of a "Faraday cage" open at the top, there was no evidence for interference with sound or cabled video cameras. It was close enough to have sparks within perhaps 10 feet of the judges (it could have safely been a lot closer with my design - tested to within 2 feet).
Draw was assumed to be around 75A from two paralleled 32A 250V outlets (= 18kVA).

The grounding with downwires from the frame allowed confidence in preventing capacitative voltages appearing on equipment and operators. It is my belief that this is more important than RF interference. Certainly this was as close as my operators have been and no tickle from holding the variac!

1302785535 10 FT107519 Agtjudgescreen350cm

Judge screen made from fine copper downwires

1302785535 10 FT107519 Agtjudgescreen500cm

The judge screen at the distance it was planned for.

1302785536 10 FT107519 Tc18arcweldersx6rear

Arc welders used for isolation (or ballast)

1302785536 10 FT107519 Tc18distributionboxes3phase

3 phase distribution boxes.

1302785536 10 FT107519 Agttrailerbunbury

The larger items in the trailer eventually overflowing.

Yes, that's a semitrailer in the foreground.

The setup with full surround and ground sheet plus filming black backdrop.

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