Way OT, but since magnetic fields seem to be "in" at the moment

we all know that magnetic fields assert a force on magnetic materials or on wires carrying a current, but just how much, we discovered last week when we tested a 2.44 MJ module at full power for the first time (24kV & 26 kA).

At the output of the module there is a pulse shaping (and module protection) 8mH coil made up of four individual coils arranged as a quasi-toroid. The first two capacitors - in mild-steel casings - in the module, stand about 15 cms behind this coil, or perhaps I should say stood! After a single ~50ms pulse both capacitors (firmly held in place at the top by their buss-bar connections) had swung forward about 10 cms to hit the module frame immediately behind the coils. These capacitors are about 1.60 m high and weigh 180 kg each!



Similarly one of the connections to the coil - 20 mm diameter copper tubing with a wall thickness of ~2,5 mm was bent through 45° and shoved down by a few cm.



and afterwards -



Subsequent calculations suggest that the magnetic field exiting the centre of the individual coils is ~10T. Measurement on the replacement capacitor during 12 kV pulse indicated a field of 0.3 T. For comparison, the electro-magnets that are used by car-wreckers/scrapyards to transport the cars generate about 0.5T.

I guess we'll need to make a few mods.

By the way, apart from that minor problem, the PLC performed faultlessly although I may need to modify the module fault screens in the HMI to indicate capacitors which have moved out of position!

Nasty!!!

I wondered why my watch was an hour out !

But what does it do?

It's the output end of one module of the world's largest capacitor bank (only discovered that tit-bit, myself, last week). It will be used to power the magnetic coils to produce what will be the world's strongest magnetic field - always assuming they can find away to get the magnet to stay in one piece! They are aiming at 100 T, current world record is ~64 T. Above ~70 T the forces involved are high enough to disrupt steel at a molecular level so the coil windings are supported by layers of a kevlar-like material.

Researching the coils will be the main job for the next couple of years. In 2007 the facility will be available for use by scientists world-wide for fundamental materials research.

Interesting project!

Wow

Wow! That is very cool! I would love to work on an amazingly large and complex research project, to push the envelope of human ability…and destroy some stuff along the way. You sir, are living my dream.

Coil question

Is that a motor operated disconnect switch above the coils? Were you using vacuum breakers to make and break the circuit?

Just curious.

Can we say LEVITATE?

Most caps of the style in the pic I have seen had built in flanges to BOLT them DOWN. I did not see any type of anchoring points on them.

I worked with 2300 and 4160 volt VFD's that if the caps, transformers and inductors were not bolted down they always moved every time power was applied.

Did your hair stand on end? Did they make everyone remove watches, jewelry and all metal objects before getting close?

Leadfoot said:

Did they make everyone remove watches, jewelry and all metal objects before getting close?

Click to expand...

I'll bet the plant did a drug screening of employees for iron supplements!!!

Amazing! do you power it from the grid or have your own generators?

ever tried to shrink your own coins...?

www.teslamania.com

chendrixson said:

Is that a motor operated disconnect switch above the coils? Were you using vacuum breakers to make and break the circuit?

Just curious.

Click to expand...

Yes, they are normal motor operated disconnect switches. They are normally used in power distribution applications with a continuous current rating of 20 kA and a peak rating of 60 kA at 24 kV 50 Hz. We aren't switching under power evrything is set up in advance and the pulse (max. 26 - 36 kA for 10 - 2000 ms, depending on module) is triggered by a laser-diode triggered Thyristor, so there is no need for vacuum breakers.

Can we say LEVITATE?

Most caps of the style in the pic I have seen had built in flanges to BOLT them DOWN. I did not see any type of anchoring points on them.

I worked with 2300 and 4160 volt VFD's that if the caps, transformers and inductors were not bolted down they always moved every time power was applied.

Did your hair stand on end? Did they make everyone remove watches, jewelry and all metal objects before getting close?

Click to expand...

No, there aren't any flanges on these ones. The manufacturer has about 700 in use worldwide, but I assume they never had them standing near a coil producing a magnetic field that intense. I assume that at 180 kg weight, they don't normally have this problem!

During experimental runs nobody is normally allowed in the capacitor hall. Occasionally, if we want to observe something particular during testing, somebody may be in the hall during tests up to a maximum of 10 kV, but over that it's too risky. They may look big, but these modules are squeezed down to the most compact size posssible, so it won't take a lot in the way of dirt, dust spiders etc. to cause a flashover.

Amazing! do you power it from the grid or have your own generators?

Click to expand...

Strangely enough, it's not that expensive, precisely because it's a pulsed field which they are creating. At field strengths up to about 40 T the pulse can be up to 2 seconds long which is an eternity at atomic levels. For the 100 T field the pulse will be about 10 ms, but even that is effectively steady state at atomic levels.

According to an article in one of the German popular science magazines, each pulse will cost only 2.30 €! In comparison the most powerful steady state magnetic field in the world, the 40 T unit at Tallahassee, has its own 20 MW generating plant - running continuously!

Did they make everyone remove watches, jewelry and all metal objects before getting close?

Click to expand...

They don't actually go that far, but even the corridor outside the laboratory where the coils are housed are locked during experiments. The walls of the coil room itself are over two feet thick and the blast-proof door is 12" thick. The room is laid out to withstand a blast the equivalent of several kg of TNT (sorry, can't remember the exact number off hand). Here's a photo of the door.

EDIT: Sorry guys, don't know what's wrong. The pic uploaded OK, but it won't display.




I've taken a few more pics of the capacitor hall this morning, but it'll have to wait for the weekend before I can get them down from the camera to post.

Funny, I see that the picture of the blast door is now visible.


Anyway as promised here's a pic of the capacitor bank hall showing about 15 of the 21 modules (I'm standing on top of the first one).



And this is the so-called "Collector" (sorry, "Kollektor" since we're in Germany!) where the output of up to 16 of the modules comes together to be routed to the main magnet coil. Maximum pulse current - 365 kA.

Roy

Here's a news item I stumbled upon (sorry, make that Stumbled Upon) the other day. Is this your handiwork? http://www.expatica.com/actual/article.asp?subchannel_id=26&story_id=34619 I can't imagine there are two teams in Germany both with the money to spend on high T elelctromagnets!

Regards

Ken