highest power resistor ever made?

[djacobow]

1.4 GW?

https://ieeexplore.ieee.org/document/1601490

[BrianHG]

10kw resistors at Aliexpress
10kw resistors at Aliexpress

3kw trimpot at Aliexpress
3kw trimpot at Aliexpress

[T3sl4co1l]

Could be.  I only see this vid,
https://www.facebook.com/watch/?v=10154155355534374
which 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

[David Hess]

Well, 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.

When the energy is dumped into a resistive load it is called "dynamic braking", like with diesel-electric locomotives.

A commercial vendor of braking resistors for the railway industry:  http://www.hilkar.com/railway-resistive-and-inductive-elements.html
Another example of a commercial high-power resistor to replace the dynamic brakes in EMD locomotives:  https://www.dayton-phoenix.com/productCategoryDetail.php?categoryId=108
Dayton's summary: 
    Manufactured by Dayton-Phoenix Group since 1954
    Over 100 part numbers offered for both domestic and export locomotives
    Service repair parts for locomotives from new to 35+ years old
    Resistances from 0.5 ohms to 3.0 ohms
    Resistor designs handling up to 1000 amps
    Competitive pricing

The 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/5OwMzI9P79c
https://youtu.be/mCk21G2LR-M

I know for really big high voltage loads, they may build resistors out of water columns with a salt like copper sulfate added.

[TimFox]

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.

[redkitedesign]

Suprised 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.

You 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.

[eutectique]

Marconi's Clifton, Ireland spark-gap transmitter condenser (That's a man standing down there)

I want to hear it humming (the condenser, not the man).

[richard.cs]

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.

[MisterHeadache]

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

[Gyro]

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.

Interesting, I thought supply grid fault current limiting was all done using reactors. They do look 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.