highest power resistor ever made? - Page 1
Forum section: electronics / projects

author: coppercone2
author_rank: Super Contributor
timestamp: February 11, 2023, 09:35:32 pm
content: So its a simple device, but I was wondering what the highest power dissipation resistor ever made was. And I don't mean like a heater for a process (too easy). Like something that looks like a resistor that you have on circuit boards. Pictures would be nice.

author: coppercone2
author_rank: Super Contributor
timestamp: February 11, 2023, 09:45:43 pm
content: lmfao, what is that for? Wind turbine maybe?The wire going to it is not that big though, but its all about the value.

author: ajb
author_rank: Super Contributor
timestamp: February 11, 2023, 11:30:41 pm
content: Quote from: coppercone2 on February 11, 2023, 09:35:32 pmSo, does this count?It's the standard braking resistor assembly on Haas CNC machines, at least on the DS30Y and VF4SS ranges, but if it looks like a stack of (4) bog standard electric stove burners, well, that's exactly what it is.I asked the tech who commissioned our VF4 about them and apparently they will start to glow if you're rigid tapping a lot of holes (where the spindle speed and z axis speed are synchronized to the pitch of a tap to create threads in a hole), since the whole 30HP spindle has to stop and reverse directions twice for every hole.Along similar functional lines, the braking resistor grids used on diesel-electric locomotives must be pretty high power--they can produce a couple megawatts of traction power, not sure what sort of braking power they can produce.Or load banks used to test generators--those would also be on the order of megawatts for the whole setup, although it depends on what you count as "a" resistor.

author: coppercone2
author_rank: Super Contributor
timestamp: February 11, 2023, 11:48:11 pm
content: I liked the green ones betterSuprised they don't do regen breaking for CNC machines, seems like a giant waste. They already super expensive so you might as well go green.

author: themadhippy
author_rank: Super Contributor
timestamp: February 12, 2023, 12:01:20 am
content: 1800kW big enough?

author: ajb
author_rank: Super Contributor
timestamp: February 12, 2023, 12:12:49 am
content: Quote from: coppercone2 on February 11, 2023, 11:48:11 pmWell, they DO use regenerative braking, that's where the energy that ends up dumped into the resistors comes from, once that energy exceeds what the DC bus can absorb without an unacceptable increase in voltage. Spindle drives are just like any other VFD in that respect. They just don't pump that back into the grid, which I guess is what you mean. That would add a bunch of complexity (technical and regulatory) for a limited amount of benefit--in general the amount of energy you could recover from spindle braking is going to be a very small fraction of the power a CNC machine consumes. There just isn't THAT much inertia even in a really big spindle, compared to an electric vehicle or something, and typical cycles don't need to decelerate the spindle that frequently. A big lathe with a big heavy chuck/workpiece could recover more energy due to the much higher inertia, but would still require a lot of extra complexity for something that might provide a small amount of benefit I'm a few select use cases.

author: coppercone2
author_rank: Super Contributor
timestamp: February 12, 2023, 12:29:01 am
content: Quote from: themadhippy on February 12, 2023, 12:01:20 amThose use fluid cooling? Yeah I did not think of that, I meant air cooled ones. When fluid gets involved things get silly, IMO that falls under heater. But that does look like a physics device of some sort.

author: coppice
author_rank: Super Contributor
timestamp: February 12, 2023, 12:40:12 am
content: Quote from: coppercone2 on February 12, 2023, 12:29:01 amBut all the best power resistors use water cooling. I used to know of a dummy load resistor for high power testing whose cooling system was a swimming pool. That pool could be quite toasty in a UK winter.

author: Ground_Loop
author_rank: Frequent Contributor
timestamp: February 12, 2023, 02:44:55 am
content: I worked in a nuclear power test facility where we dumped up to 35MW into a water cooled resistor bank. I never actually saw the resistors though.

author: coppercone2
author_rank: Super Contributor
timestamp: February 12, 2023, 04:03:31 am
content: there is something to say about not having the thing melt down because a pipe clogged. The high temp resistors always impressed me, especially if they DONT glow.Resistor #1 is like arnold schwarzenegger, resistor #2 is like the ABC warrior from the first judge dredd movie, its grotesque and resistor #3 is like a borg with pipes coming out of its head. All powerful but IMO the first one holds to some ideals

author: EPAIII
author_rank: Super Contributor
timestamp: February 12, 2023, 08:23:20 am
content: Well, you have me beat by three orders of magnitude. I have used a number of 25 to 50 KW water cooled, coaxial dummy loads. The element was a glass tube around 1" diameter and a foot long, with a resistive film deposited on it. The water flowed around and through it. If the water flow stopped for even a second, it turned into a pile of glass fragments. On the outside it looked like a section of 3" coaxial line with water couplings. The power was measured with a flow meter for the water and thermometers on the pipes entering and leaving it. Just standard dummy loads at TV stations. Oh, and the impedance was 50 Ohms, of course. They do make air cooled ones in the range of hundreds of Watts, perhaps as much as one kWatt or so. But they start getting fairly big and need cooling fans.And then there was a load at a used generator facility I visited once. A tank of water as big as the office I am sitting in typing this. I was told it had salt dissolved in the water and that was the element, the salt water. I can't remember the rating.Quote from: Ground_Loop on February 12, 2023, 02:44:55 am

author: EPAIII
author_rank: Super Contributor
timestamp: February 12, 2023, 08:35:42 am
content: PS: You can not get away from the heater thing. Resistors ARE heaters. Every single resistor on every single PCB that I, you, or anyone has ever work with basically turned electric energy into HEAT energy. That is what they do and how they do it. Period! They are all heaters, just different sizes.It is called entropy. And it means the universe is steadily and irreversibly running down. But don't worry, it will take a while.

author: moffy
author_rank: Super Contributor
timestamp: February 12, 2023, 10:47:17 am
content: When load testing the alternator for a 2000 to 4000HP diesel electric locomotives they would use resistors made from plates of stainless steel with massive cooler fans:https://www.cressall.com/legacy/resistors-for-rail-traction/locomotive-testing/An older installation I heard of used a large tank of salted water, with upper plates that were lowered in or out like control rods in a nuclear reactor to control resistance. They had to keep topping up the water as it would naturally boil away. I was only old about it, I never saw it.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: February 12, 2023, 04:13:47 pm
content: A city, from the point of view of the generator.

author: fourfathom
author_rank: Super Contributor
timestamp: February 12, 2023, 04:25:40 pm
content: How about the biggest capacitor? I don't know if this one qualifies, but it sure is big:Marconi's Clifton, Ireland spark-gap transmitter condenser (That's a man standing down there)

author: coppice
author_rank: Super Contributor
timestamp: February 12, 2023, 04:29:04 pm
content: Quote from: fourfathom on February 12, 2023, 04:25:40 pmThere are some pretty massive ones used for PFC in the grid.

author: themadhippy
author_rank: Super Contributor
timestamp: February 12, 2023, 04:29:18 pm
content: Quotesalt water dimmers,one of the earliest ways of dimming those new fangled electric lights in theatres.

author: coppercone2
author_rank: Super Contributor
timestamp: February 12, 2023, 04:45:45 pm
content: Most of these things are not qualified for this thread, its like bringing roided out cybernetic experiments to mr olympiaI wanna see a 3 foot long resistor with solid bus bar leads that are bent and brazed into place, enough with this rubbish with bolts and holes and lugs (considered surface mount). Or better yet solid round copper conductor w/titanium inner structure that is brazed into holes in copper plane like a real PCB, so you form the resistor with a pipe bender (considered classic through hole). Installed with a 2 lb clip on heat sink with gold bearing silver braze on halfnium-thorium ceramic substrate via magnetically focused carbide torch. (subspace array qualified components grouped under standard WY-1231 or atmospheric processor fusion quality standard WY-49a.2.12III compatible with deep space reliability standard WY/TYR-99a5 and the classic TyrellC NEF1 guidelines ).

author: TimFox
author_rank: Super Contributor
timestamp: February 12, 2023, 05:20:01 pm
content: A commercial vendor of braking resistors for the railway industry:http://www.hilkar.com/railway-resistive-and-inductive-elements.htmlAnother example of a commercial high-power resistor to replace the dynamic brakes in EMD locomotives:https://www.dayton-phoenix.com/productCategoryDetail.php?categoryId=108Dayton's summary:Manufactured by Dayton-Phoenix Group since 1954Over 100 part numbers offered for both domestic and export locomotivesService repair parts for locomotives from new to 35+ years oldResistances from 0.5 ohms to 3.0 ohmsResistor designs handling up to 1000 ampsCompetitive pricing

author: Laurencewilliams
author_rank: Newbie
timestamp: February 12, 2023, 05:44:23 pm
content: The highest power resistor ever made would depend on the definition of "highest power." Power in a resistor can be defined in terms of its maximum power dissipation or maximum permissible power dissipation. The power dissipation is dependent on the resistor's physical size, temperature coefficient, and material properties.Typically, high-power resistors are made from materials like ceramics, metal alloys, or even graphite, and can have power dissipation ratings in the range of tens to several hundred watts. However, there are some specialized high-power resistors that are designed to handle even higher power levels and can have power dissipation ratings in the kilowatt range.It's worth noting that the highest power resistor is not necessarily the most efficient or practical option for every application, as other factors such as cost, size, stability, and accuracy also play a role in determining the best choice of resistor for a given application.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 12, 2023, 05:56:23 pm
content: I recall once finding a GIF that was something like, a couple towers (similar to HV transmission towers) with stainless cable strung between them, which started to glow subtly red over some 10-20s. Low res GIF though. Caption was something like, power station disconnect test, switch over to load dump. So, three-phase resistor of probably some ohms, and many megawatts. Haven't found the same clip in a long time though...Tim

author: coppercone2
author_rank: Super Contributor
timestamp: February 12, 2023, 05:58:21 pm
content: Here is the biggest resistor I could find on digikey that is nicehttps://www.digikey.com/en/products/detail/te-connectivity-passive-product/TE2500B47RJ/2367859There are some bigger ones on alibaba (10kW), but I am not sure how that rating translates

author: Gyro
author_rank: Super Contributor
timestamp: February 12, 2023, 06:39:25 pm
content: Quote from: T3sl4co1l on February 12, 2023, 05:56:23 pmI think these were dissipating a fair bit!https://www.eevblog.com/forum/chat/magic-smoke-lots-of-it/

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 12, 2023, 07:56:37 pm
content: Quote from: Gyro on February 12, 2023, 06:39:25 pmYeah, that was a nasty day for all affected!Tim

author: djacobow
author_rank: Super Contributor
timestamp: February 12, 2023, 08:16:24 pm
content: 1.4 GW?https://ieeexplore.ieee.org/document/1601490

author: BrianHG
author_rank: Super Contributor
timestamp: February 12, 2023, 08:32:27 pm
content: 10kw resistors at Aliexpress10kw resistors at Aliexpress3kw trimpot at Aliexpress3kw trimpot at Aliexpress

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 12, 2023, 08:35:12 pm
content: Could be. I only see this vid,https://www.facebook.com/watch/?v=10154155355534374which isn't what I was thinking of and lacks glow (and doesn't really give a good sense of scale, it looks rather small in this frame?!), but is still impressive seeing that much smoke burning off if nothing else.Tim

author: David Hess
author_rank: Super Contributor
timestamp: February 13, 2023, 01:04:33 am
content: Quote from: ajb on February 12, 2023, 12:12:49 amWhen the energy is dumped into a resistive load it is called "dynamic braking", like with diesel-electric locomotives.Quote from: TimFox on February 12, 2023, 05:20:01 pmThe resistors for diesel-electric dynamic braking is what I thought of first. On older locomotives, they are located in projections sticking out to the side of the top of the body. Sometimes they fail:https://youtu.be/5OwMzI9P79chttps://youtu.be/mCk21G2LR-MI know for really big high voltage loads, they may build resistors out of water columns with a salt like copper sulfate added.

author: TimFox
author_rank: Super Contributor
timestamp: February 13, 2023, 04:33:14 am
content: Also, dynamic brake resistors for diesel locomotives are normally cooled by force air from fans at the top of the locomotive body.They are optional: flat-topography railroads normally don't buy them.

author: redkitedesign
author_rank: Regular Contributor
timestamp: February 13, 2023, 11:22:44 am
content: Quote from: coppercone2 on February 11, 2023, 11:48:11 pmYou can only dump power in the grid when the grid voltage is low enough, like some solar owners are realizing right now.For a CNC, you want the brake to be reliable, not to depend on the grid voltage. So even if you could dump into the grid, you would still need the resistor for reliability.

author: eutectique
author_rank: Frequent Contributor
timestamp: February 13, 2023, 12:08:32 pm
content: Quote from: fourfathom on February 12, 2023, 04:25:40 pmI want to hear it humming (the condenser, not the man).

author: richard.cs
author_rank: Super Contributor
timestamp: February 13, 2023, 03:40:22 pm
content: Neutral earthing resistors (earthing the star point of a 3 phase high voltage transformer, such as to limit the line to earth fault current to a few kA) are usually rated for tens of megawatts* for tens of seconds. This kind of thing:https://www.acrastyle.co.uk/products/liquid-neutral-earthing-resistors/*Say, at the source of a 33 kV (line-line) distribution line, and you want to limit the earth fault current to 5 kA, so it needs to be 19 kV / 5 kA ~= 4 Ohms, and dissipates 95 MW in use. The earth fault protection should open in a few seconds, but the resistors are often rated for around 30 seconds.

author: MisterHeadache
author_rank: Regular Contributor
timestamp: February 13, 2023, 05:08:52 pm
content: Decades ago I worked for Komatsu (back when they were called Komatsu Dresser) on their electric haul trucks. Those have powertrains very similar to diesel electric locomotives. Because these trucks must descend into deep open pit mines they need dynamic braking, which (again similar to locomotives) turns the motors into generators and the potential energy of the truck is made into heat using an object called a 'dynamic retarder'.Think of it as a giant hair dryer, resistive elements with an air turbine to move a lot of air over the elements. When running full tilt it sounds like a junior jet engine.I just looked it up, their largest dynamic retarders are now rated at 5,400 horsepower (that's almost 4 Megawatts), all as heat.https://www.komatsu.com/products/trucks/electric-drive-mining-trucks/930e-5se/#specifications

author: Gyro
author_rank: Super Contributor
timestamp: February 13, 2023, 06:49:53 pm
content: Quote from: richard.cs on February 13, 2023, 03:40:22 pmInteresting, I thought supply grid fault current limiting was all done using reactors. Theydolook cheaper and a lot easier to handle than heavy windings embedded in concrete frameworks though.Edit: Looking at web images, the current ones don't seem to use concrete any more, although the construction is obviously still very heavy.