largest value passive components in existance? - Page 1
Forum section: electronics / general

author: SArepairman
author_rank: Frequent Contributor
timestamp: April 26, 2014, 04:02:05 am
content: So I am wondering about the largest capacitors (or banks) and inductors in existence.I know making a large resistor is fairly "easy" compared to massive value inductors or capacitors.I know a transformer is a inductor technically, but I mean non transformer inductors.I saw fairly massive inductors in pages describing the creation of transmitters for ELF/VLF type signals, military stuff the size of 50 gallon drums. And I have not a clue for capacitors, I imagine that railgun power supplies must be close to the worlds largest.What are the extremes in existence?

author: Whales
author_rank: Super Contributor
timestamp: April 26, 2014, 04:16:51 am
content: I would have though power grids use the biggest passive gear:https://commons.wikimedia.org/wiki/File:Forest_Hill_Substation.jpg...but the more I think about it, substations probably only have transformers. Caps and inductors would not be intentionally used at two-terminal style components.

author: Teledog
author_rank: Regular Contributor
timestamp: April 26, 2014, 04:20:00 am
content: A bit off topic..but Google "Arc Rectifier tube" {the images}I want, err, "need" one ...for the eerie glow ;-)

author: SeanB
author_rank: Super Contributor
timestamp: April 26, 2014, 05:37:42 am
content: The grid substation will have both line reactors, power factor correction capacitors and massive VDR units to do power factor correction and overvoltage limiting on the system, to present a close to pure resistive load to the generation side and to reduce losses in the transmission lines.

author: VK3DRB
author_rank: Super Contributor
timestamp: April 26, 2014, 06:00:36 am
content: The planet Earth is the largest passive component by far.

author: nitro2k01
author_rank: Frequent Contributor
timestamp: April 26, 2014, 06:16:48 am
content: Quote from: Whales on April 26, 2014, 04:16:51 amCaps and inductors are sometimes used in power stations for power factor correction, either for phase compensation (for long transmission lines) or a tuned filter for filtering away unwanted harmonics. The latter is often used after HVDC to AC conversion. And especially in HVDC back to back converters (AC-DC-AC) between a 50 Hz and a 60 Hz grid, where you would otherwise get intermodulation distortion on harmonics common to both frequencies, like 300 and 600 Hz. That specific scenario (HVDC back to back, between 50 and 60 Hz) exists between Japan's southern and northern regions, and between Brazil and Argentina to name two examples.But I'm still not sure those are necessarily the biggest capacitors and inductors out there. Probably not by value, and possibly not even by energy capacity. I think this is more likely to be found in a purpose-built device like the aforementioned railguns.One type of device worthy of mention is the Marx generator, which is a high voltage generator that works by first charging a bunch of capacitors in series, then making them couple in parallel by triggering a chain reaction in a bunch of spark gaps. See image 1 for the working principle. If nothing else, these devices are capable of producing extremely high voltages and extremely fast power dissipation. Marx generators are for example used for insulation testing of high voltage power line components. (See image 2 for an example of such a device.) The biggest currently operational Marx generator is the Z Machine, which is used for fusion research and producing X rays. To list some maximum numbers: Maximum instantaneous power: 350 TW. Radiated energy, 2.7 MJ. Maximum temperature achieved 3.7 GK. (That's gigakelvin.) Maximum pressure, 12 GPa, enough to turn water into solid ice by pressure alone. See image 3 for the money shot of a flashover in the facility, where electrical arcs are formed between metallic objects, on top of the deionized water pool which is used as an insulator.

author: XOIIO
author_rank: Super Contributor
timestamp: April 26, 2014, 06:19:08 am
content: Quote from: Teledog on April 26, 2014, 04:20:00 amYeah, those things are awesome. I think photonicinduction has one, he is lucky lol.

author: peter.mitchell
author_rank: Super Contributor
timestamp: April 26, 2014, 07:27:43 am
content: I'm definitely in agreement here with HVDC reactors used for smoothing (inductors)They are massive, not sure how they compare to passives in things like railguns though;This is a random reactor from google images;http://www.tmc.com.au/cache%5C4%5C5452d43aa908051b61a94d4de6288251.jpg

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 26, 2014, 08:27:26 am
content: Yeah, power transmission stuff is going to be the biggest in terms of power rating -- sheer VAs, continuous duty.Z machine is a good example of transmission lines, not so much caps and inductors explicitly; and you'll have a hard time finding anything of greater total peak power.If you want to talk physical phenomena, a magnetar (neutron star with exceptionally high magnetic fields, I forget why) is probably the most powerful by a number of metrics: inductance (inferred from the fields -- since it's not really a coil of neutronium wire and all to stick probes onto), energy storage, power output (besides supernovae and black holes' accretion disks, of course) and so on. We just have to make sure they exist first...Tim

author: rsjsouza
author_rank: Super Contributor
timestamp: April 26, 2014, 11:19:04 am
content: Itaipú damin Brazil/Paraguay has one of the world's largestDC links(1.2MV/3GW across 800km). Being DC generated from AC from the dam, naturally the output of the rectifier is filtered by a bank of capacitors and inductors up to the 13th harmonic (IIRC). These are the largest passives I have ever seen.I couldn't find detailed pictures of the filter on the web and I can't find the pictures I took years ago, but some arehereand an overview of the conversion site ishere.

author: Teneyes
author_rank: Frequent Contributor
timestamp: April 26, 2014, 01:28:12 pm
content: Yes , Power grids have large Capacitors banks, not only for power factor correction , but for high frequency noise (odd harmonics) . Near me there is a large industry that has200MW of SCR rectifiers,and with only 6 pulse rectification there is a lot of noise fed into the the power grid. so much so that the noise made the telephone lines unusable. So large capacitor banks had to be add on the 66KV transmission lines to filter the noise.

author: SeanB
author_rank: Super Contributor
timestamp: April 26, 2014, 01:42:40 pm
content: Aluminium refinery or steel scrap recycler then.

author: Teneyes
author_rank: Frequent Contributor
timestamp: April 26, 2014, 04:08:59 pm
content: Near Me, Zinc electrowinning,

author: SeanB
author_rank: Super Contributor
timestamp: April 26, 2014, 04:36:15 pm
content: Pretty much the same, large DC power supply. Control likely either with literally a shed full of SCR's or still using mercury arc rectifiers.Funny enough no power by me today, Metro was changing out the 500kVA transformer in the substation as it had an oil leak on the lower side valve flange. the substation building itself dates back to the 1900's and used to house a transformer, mercury arc rectifier and control gear to give 500VDC to run trolley buses that used to run past here. No parts left aside from the original wiring for the room lighting, and the old hold down bolts in the floor in the room where the mercury arc tank was, and the hall very empty now where the old control gear banks were, now only holding a 11kV switch and a 6 way 400VAC distribution fuse panel. Fuses are mostly 400A, though there are some older 315A and some 200A fuses in the mix. Some are older than me. Took them 5 hours to do the transformer swap.

author: G7PSK
author_rank: Super Contributor
timestamp: April 26, 2014, 04:42:52 pm
content: Quote from: rsjsouza on April 26, 2014, 11:19:04 amYou would not stick your finger in there more than once.

author: Zero999
author_rank: Super Contributor
timestamp: April 26, 2014, 08:35:58 pm
content: Quote from: nitro2k01 on April 26, 2014, 06:16:48 amI must point out that large Marx generators use inductors, rather than resistors to charge the capacitors, to minimise power dissipation. The maximum theoretical efficiency of a resistive Marx generator is only 50% but if inductors are used, it can be unity but in practise it's much lower.

author: nerdyHippy
author_rank: Contributor
timestamp: April 26, 2014, 08:46:30 pm
content: Quote from: VK3DRB on April 26, 2014, 06:00:36 amHow fortunate that out of all the planets in the universe we happen to live on the one that's the largest passive component.

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 26, 2014, 09:01:40 pm
content: When bouncing RF signals (or laser beams) off the moon, the Earth and the moon are acting as a very big delay line. In theory, you could do the same with another planet, but it's hard enough to get a usable signal back from the moon...

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 27, 2014, 05:06:49 am
content: That said, Venus (and others I think) have been radar imaged.Oy..Tim

author: miguelvp
author_rank: Super Contributor
timestamp: April 27, 2014, 05:36:42 am
content: Not to mention radio telescopes scanning the universe.Edit: but I guess those are active, unless you count objects detected in between the source and the radio telescope.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 27, 2014, 06:49:19 am
content: Which has been standard in radar for some time, and is gradually being picked up on for astronomy. There have already been a few objects (wasn't that "Planet X" one of them?) detected by their transit of background stars!Tim

author: TerraHertz
author_rank: Super Contributor
timestamp: April 27, 2014, 12:01:49 pm
content: Sydney has two primary electricity substations, taking overland transmission lines from the Hunter valley power stations in the Nth, and the Kosciusko hydro system in the Sth. I don't know if the capacitor banks they use to compensate for the inductance of the overland transmission lines are the biggest in Australia, but they are probably close.Here's one of the capacitor banks at 'Sydney North' station:https://maps.google.com/maps?hl=en&ll=-33.657044,151.031014&spn=0.000477,0.000534&t=h&z=21Somewhere I have up-close photos of this, but I can't find them just now. Maybe they were only on film.

author: SeanB
author_rank: Super Contributor
timestamp: April 27, 2014, 12:34:25 pm
content: Largest inductor on earth is the ducting of electrons between the magnetic poles from the solar wind. Makes VLF whislers heard on long telegraph lines.

author: VK5RC
author_rank: Unknown
timestamp: April 27, 2014, 12:50:53 pm
content: What about the Large Hadron Collider, isn't it a giant electromagnet+++++.

author: nitro2k01
author_rank: Frequent Contributor
timestamp: April 27, 2014, 01:19:39 pm
content: Quote from: Hero999 on April 26, 2014, 08:35:58 pmHmm, interesting. Doesn't that also create a lot of ringing after the device has been triggered?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 28, 2014, 05:34:42 am
content: Quote from: VK5RC on April 27, 2014, 12:50:53 pmProbably many of them. All the important ones are superconducting though. You can say this for sure: there's nothing that makes 10T+ fields that isn't storing a lot of energy. And we're talking miles of beam line here...The ITER tokamak's main field coils, I believe, are rated at something like 10H and a thousand amperes.Tim

author: VK5RC
author_rank: Unknown
timestamp: April 28, 2014, 10:31:13 am
content: I am not an EE but I must imagine the problems of releasing that stored energy must be very challenging! I don't really understand what would happen to a superconducting coil when you switch off the electricity, the 'back EMF' could be terrible or perhaps the superconducting properties mitigate it to some degree.I friend I cycle with (a radiologist) was talking about MRI imaging machines (a few Tesla) in which they leave the main magnet ( a liquid nitrogen cooled superconductor) powered on the whole time, when they want to shut down they let it warm up first!

author: SeanB
author_rank: Super Contributor
timestamp: April 28, 2014, 10:41:16 am
content: The big problem with superconductors is turning them off when charged with current, as the energy has to be dissipated somehow. Letting it warm up till it transitions to a regular conductor has the problem that it suddenly results in massive heating inside the conductor, which stresses it. With MRI they have to sheath the superconductor with silver coated copper to allow it to dump the energy in the copper coat's resistance more or less safely, though that heats the windings very fast, and with time will crack the brittle ceramic superconductors inside, needing the coil to be replaced. Thus most MRI units will never be turned off, and will have enough backup to allow the cryocoolers to operate for a long time if the power fails.

author: VK5RC
author_rank: Unknown
timestamp: April 28, 2014, 11:51:29 am
content: Thanks seanB. Interesting! When I did a quick google about the LHC, I noted the huge energy requirements and one proviso that Wikipaedia mentioned was the power contract is on an "Instant cut off" if loads need it basis, your comments on back up for a 'simple' medical imaging MRI machine made me think as I work next door to one and the cooling fans work day and night, the 'back up' power supply and the switch off routine for the LHC must be complex.I will tackle my Radiologist friend a little more about the switch off routine, I suspect the MRI Radiographers have more to do with that side of things, as an aside he had some photos of the room they are about to install a new MRI machine in, the copper plate lining was impressive and the single door also part of the Faraday cage. The venue is directly over a car park and once a car is parked directly below the MRI unit, for consistent field density in the machine, the car can't be moved without a 20min or so recalibration, staff carpark!!

author: SeanB
author_rank: Super Contributor
timestamp: April 28, 2014, 12:04:40 pm
content: LHC did have some issues during initial testing in that a few magnets had a cooling failure and quenched, and destroyed themselves.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 28, 2014, 12:06:16 pm
content: You discharge it the same way you charge it, doi.Suppose you charged it with a 12V car battery (this could take a while at 10H and 1000A..), once it reaches nominal current you short the terminals and everything's happy -- it sits there dissipating no power, developing no voltage, just lots and lots of electrons sliding around. To discharge, simply hook it up to the battery backwards -- the 1000A (and less as it discharges) charges the battery. When current reaches zero, you can safely open circuit the inductor. Just as a capacitor, at zero volts, can be safely short-circuited for storage. And by analogy... never open circuit a charged inductor: you'll get one hell of a lovely arc off a superconducting magnet.I once heard a company developed a UPS based on superconducting storage -- you'd basically short out the inductor with an inverter when not needed (you will have to keep pumping a little flux into it to account for the inverter's losses), then hook it to the AC line alternately when needed. Can't imagine the value is all that great though; efficiency under heavy use should be good, but the refrigeration power isn't so attractive, especially over long periods of inactivity.Tim

author: VK5RC
author_rank: Unknown
timestamp: April 28, 2014, 12:14:17 pm
content: Must be one hellofa switch, make before break or vice versa? Some pretty nasty switching issues. Leave the magnet open it will bite you, short the 'battery' similarly I would imagine.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 28, 2014, 12:17:16 pm
content: Shorting the car battery for a few microseconds would certainly be a much better alternative to opening a few kilovolts at the same current, but yes, if you're going from CV to CC sources, you'll want to make sure you keep things straight. It's just a big slow buck converter, nothing unusual about that in power electronics.Tim

author: SeanB
author_rank: Super Contributor
timestamp: April 28, 2014, 12:26:09 pm
content: Except that if a small single bit of the superconductor decides to quench it will generate a very quick pulse of heat, and that in turn will trigger the entire area around it to stop superconducting, and then the remaining superconductor will be above it's critical current density and the whole lot will suddenly become a regular conductor. If you have pumped 1Mj of energy into the magnetic field having it all dissipated in 1ms in a small area will definitely take it from 50k to over 500k in under 1 millisecond. Expansion alone will do some severe damage, let along the sudden evaporation of a few litres of cryogenic nitrogen into gas. doubt it will diffuse out through the cooling channels fast enough to not pop things. That assumes it is a high temperature superconductor, if it is one of those that only occur at liquid helium temperatures then the entire structure will behave as if it was made from crystalline sugar, as it will be brittle.

author: JulietMikeBravo
author_rank: Contributor
timestamp: April 28, 2014, 12:26:18 pm
content: Don't know about the world, but this is my largest value passive part:http://www.flickr.com/photos/julietmikebravo/8554799549/#1500 G Ohm resistor

author: jeremy
author_rank: Super Contributor
timestamp: April 28, 2014, 12:50:52 pm
content: Quote from: VK5RC on April 28, 2014, 10:31:13 amAre you sure it was liquid nitrogen? I have had a bit to do with MRIs and all of the ones I have dealt with use liquid helium? Although, the helium is usually surrounded by chamber of liquid nitrogen. To my knowledge, high temp superconductors aren't quite there yet for the medium to high field strengths (>=3T)Quenching is a really big problem in MRI because it costs a lot of time and money to refill and re-setup the machine. Interestingly enough though, in a working MRI the main culprit for heating in the main magnet is due to eddy currents induced in the superconductor by the inner coils like the gradient coils; a lot of the shielding of the main magnet is to protect it from the gradient coils. I've not heard of any machines that broke due to quenching (the venting works remarkably well), but I suppose it is possible and I don't really deal with broken ones!Also, I can vouch for the superconducting UPS idea; this has been done in MR before where the main magnet is initially "charged" and then only needs to be "topped up" at regular intervals.

author: houdini
author_rank: Regular Contributor
timestamp: April 28, 2014, 01:14:01 pm
content: I seem to recall an experimental nuclear fusion facility using some of the largest capacitors in the world for pulsed laser applications.

author: Richard Crowley
author_rank: Super Contributor
timestamp: April 28, 2014, 02:15:37 pm
content: My nomination for largest "ground rod"...QuoteIt is the ground terminal of the 3.1 Giga-Watt Pacific DC Intertie. At the other end (Sylmar, California) they use 'a line of 24 silicon-iron alloy electrodes submerged in the Pacific Ocean at Will Rogers State Beach."

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 28, 2014, 02:17:19 pm
content: Hmm, couple links down on Google:https://www.flickr.com/photos/llnl/3678999076/Looks pretty well covered up, not that I'd imagine you'd want to get your fingers mixed up with what's inside!Tim

author: jahonen
author_rank: Super Contributor
timestamp: April 28, 2014, 02:56:03 pm
content: Quote from: SeanB on April 28, 2014, 12:26:09 pmThat's why they have heaters embedded in LHC magnets, so that if a magnet quenches, then QPS (quench protection system) will fire quench heater resistors using a capacitor bank charged to several hundred volts to provoke controlled quench in entire magnet to prevent this small spot from burning, i.e. distribute the energy evenly. Quench may happen due to some stray particle dissipating its energy into the coil, so quench is a real issue in superconducting particle accelerators which tend to push the superconductors to their ultimate limits.There is also a parallel diode to a magnet which bypasses the circuit current in case a quench happens. Remember that the main magnets are series connected so there are dozen other not quenched magnets in series with the one that quenched. That diode is a heavy one, it must take up to 13 kA of current (at ultimate current, in dipole/quadropole magnets). Furthermore, there is a dump resistor which is connected in series of the magnet circuit (in normal operation, it is bypassed by a redundant switch), to speed up the current decay (it still takes 10's of seconds!) and burn the stored energy in the dump resistor instead of the cryomagnets.And, it was actually a bad interconnection between two magnets which failed during initial LHC sector testing in september 2008, interesting what one can do with 200 MJ of stored magnetic energy. But most of the damage was collateral caused by expanding helium.Speaking of big magnets, LHCb dipole magnet is another interesting one. It is a normal conducting 5.8 kA dipole magnet. Conductors are made from 50x50 mm aluminum bar, with 24 mm hole for the cooling water. Inductance is about 2 H and stored energy is 32 MJ. Nominal dissipated power is 4.2 MW. It needs 730 volts applied to keep its current due to resistive losses (source:http://lhcb.web.cern.ch/lhcb/magnet/TDR/pdf/lhcb-magnet.pdfhttp://lhcb-public.web.cern.ch/lhcb-public/en/detector/Magnet-en.html)Regards,Janne

author: lapm
author_rank: Frequent Contributor
timestamp: April 28, 2014, 08:26:44 pm
content: Quote from: VK3DRB on April 26, 2014, 06:00:36 amLol, i was going to suggest that.

author: VK5RC
author_rank: Unknown
timestamp: April 28, 2014, 09:01:49 pm
content: Apologies , it is liquid helium cooling re MRI.