Item ID required, please.

[Compo 10,328]

Can anyone identify the following piece of equipment from these photographs, please? My idea is a Van Der Graaf generator which may have been used as an electric shock device for treating "Lunatics".  The detachable wand fits neatly over the temples of my head. I am thinking that a charge would be developed by turning the handle and then the wand would be placed over the temples to give a high voltage/low current jolt. The wand is attached by friction only and just pulls off the glass cylinder. Any help would be appreciated:

 

 

 

[MargieH 7,614]

How did you find this piece of equipment, Compo?  Hope you're not going to try it out on anyone!!

[Compo 10,328]

It is in a museum but the staff don't know what it is, MargieH. The leather strip that rubs on the glass cylinder is worn out and torn so I couldn't try it out but was able to demonstrate that the iron balls on the end of the (Insulated) wand fit neatly over my temples.  That's why I am thinking it might be a medical machine.

[philmayfield 6,222]

I would guess it's a very early electroconvulsive therapy machine.

[nonnaB 4,907]

It looks like an early type of high frequency machine used in beauty therapy and hairdressing . See what Mary 47 thinks it is.

[Ayupmeducks 1,730]

Looks like part from  a Van de Graaff generator.

 

It is a Van de Graaff generator..

[loppylugs 8,429]

I wouldn't like a whack through the noggin from that thing it would make me ears stand straight up. A Van de Graaf generates a few thousand volts if I remember rightly.

[Jill Sparrow 10,361]

Isn't it what Gracie Fields used to sing about? The Thingamybob that's Going to Win the War?

 

Not that I'm old enough to remember it, of course! 

[loppylugs 8,429]

Don't know that particular song Jill, and I know a few whacky ones.  It would sure make me wet nose dry too.  

[Brew 5,440]

You're quite right Compo on both accounts. It is a Van der Graf and it was used for ECT. The design appears to have changed little since John Wesley (yes the Methodist) invented it in 1747. Scroll down to about half way to see what I mean here:

 

http://www.bible.ca/psychiatry/psychiatry-harms-damages-society-ECT-electroconvulsive-therapy-shock-treatments-thymatron-dgx-ectron-series-mecta.htm

[Ayupmeducks 1,730]

A few thousand Dave?? try a few HUNDRED thousand, static, but still give a nice kick. They were primarily used for experimentation, as well as fun.

[loppylugs 8,429]

11.   Ouch!!  Some fun eh?  

[DJ360 6,738]

It certainly looks like  Brew's picture of an ECT machine.  However, it is not a Van De Graaf Generator as that is a very different animal, developed much later... which works by rotating a belt (driven by an electric motor) to develop very high voltages.

https://en.wikipedia.org/wiki/Van_de_Graaff_generator

Col

 

.

[DJ360 6,738]

Many years ago I worked in a factory which manufactured polythene film.  (It's quite an interesting process but I won't bore you with that now....    )

Anyway.. the polythene can be anything from a couple of inches wide, to several feet wide, and as it is made it is rolled onto reels.  You soon learn that 'static' builds up on the reels as they form and you develop the habit of running your hands over reels as you pass.. to take the static off.  This can raise the hairs on your head but doesn't hurt. A common 'gag' was to have your hand on a reel and casually point your finger at someone's bare elbow to give them a little 'jolt'.

 

One night shift, I was working on some very wide and thick polythene which was filling the reels very quickly and had to have full reels taken off every couple of minutes.  To change a reel it was necessary to cut the 'poly' and quickly feed it onto an empty reel. ( The mannufacturing process is continuous.. so you can't stop it to change reels)  Being tired, I'd forgotten to put a new cardboard 'core' on the spare reel  and as I bent down to do this, the full reel gave me an electrostatic 'belt' from about 6 inches away.. straight between the eyes... 

 

Fair made my eyes water that did.... 

 

I don't know what the voltage was.  The more you read around it the more you find that there are lots of variables, such as the humidity in the surrounding air, atmospheric pressure, shape of the 'conductor ( reel..in this case)  etc.but a few sites I've looked at quote: 

 

Quote

Approxinately 3 million volts/meter to ionize the air to strike the arc (76,200 V/in). Another approximation is 75kV/in.

 

So if we go for 75Kv/inch, that would be around  450000 volts for 6". 

 

No wonder it stung!

 

Col

 

 

 

[Brew 5,440]

We had a Van der Graff at school that had a handle you turned to rather than an electric motor, though it looked nothing Compos and had a metal sphere rather than a glass barrel.

The John Wesley version was not called a VdG but the principle is exactly the same with the exception the 'belt' was static and the glass barrel revolved.

I worked on the polythene machines at a  Heanor factory many years ago installing earthing cables to try and prevent static build up. The energy generated could be significant  and although the current was quite low anything above 30mA could, in certain circumstances, be very dangerous.

[Compo 10,328]

Was that factory "Venus Packaging" Brew?

 

Thanks for the web link too.

[Brew 5,440]

There were two Compo, Venus and Alida

[Ayupmeducks 1,730]

Talking of ionizing, one of our problems with "real" against "static" electricity was on our 11Kv switchgear. We used some visible off load isolaters, which always showed a light purple haze around the three live conductors. Sometimes we'd get cubicals that ionized then flash over, once that happened it was a major overhaul and cleaning a thick layer of carbon off the insides of the cubical. I once saw the insides of a FLP, (flameproof), transformer mounted isolater that had been brought to the surface, what a mess!!

Although with static it's not really dangerous, even at hundreds of thousands of volts charge, 11Kv "real" electricity is lethal, no second chances if you are stupid enough to get close to a live circuit.

 

When I was made up to Leading Hand elec, my Engineer was going through what my authorized responsibilities were, he gave me the keys to the main 66Kv switchyard, his words were "Stay within the marked footpaths if you have to enter the yard, DO NOT stray from them while the equipment is energized"  66Kv has a nasty habit of jumping several feet!!

[Brew 5,440]

The MINIMUM distances for safe working clearance:

 

 low-voltage line – 1 m; 

– 11 kV and 33 kV lines – 3 m; 

– 132 kV line – 6 m; 

– 275 kV and 400 kV lines – 7 m;

These figures are for clean, open air, down a mine with a dusty atmosphere lord alone knows how far it could 'jump'.

If you like scary see the YouTube videos of linesmen approaching the big towers by helicopter..... and then climbing down onto live lines at thousands of volts.

https://youtu.be/FGoaXZwFlJ4

 

For images of ionisation :  https://en.wikipedia.org/wiki/Tesla_coil, some of them are impressive and generate a million volts. Are they safe? NO, is the short answer - unless you really know what you're doing.

[DJ360 6,738]

Yep.  It's all impressive stuff!  Even in school I recall my mate Rob opening out the spark gap on a Wimshurst machine and then winding like mad to try and get the longest spark ever... After a lot of winding the potential from the Leyden Jars found its way through the winding handle to Rob..

We never did see the long spark. 

 

I'm no electrician but this is one concerning 'real' electricity that would have escaped me had I not read about it, even though I sort of knew the issue.

Apparently, when miles long sections of HT lines are isolated.. they have to have residual charges 'dumped' before they are safe to work on.  This is not the carried voltage.. but capacitive storage on the line.  AIUI, all conductors exhibit impedance, inductance and capacitance to some degree.  There's a lot of capacitance on a few miles of wire..  

 

Brew #15.

 

That's interesting.  Another thing that happened in plastic film manufacture was that an electrode could  be placed close to the poly film as it was reeling.  A curved plate, as wide as the poly and set close to.  When powered up there would be a sort of violet coloured 'discharge', between the electrode and the passing film.  This was done to change the surface characteristics of the finished film so that it would accept print.   It also threw a lot of Ozone out into the atmosphere..  Not too healthy.. and I always wondered whether it added to the static on the reels.

 

Col

 

[Brew 5,440]

Col, It's true all cables will 'charge' up even when they are de-energised, they don't have to be 'miles' long. Conductors are discharged using a big resistor (sometimes called a 'dump stick') to remove any capacitive charge and then earthed.

So serious is the risk that 'Permit to work' rules apply with very specific conditions documented and signed by all parties working on the system.

[Compo 10,328]

Brew post #10: thanks for the wed address re this device. I passed it on to the museum and they are very grateful for the information.

[Oztalgian 3,350]

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