Poor Mans Salt Box Loadbank

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jrannis

jrannis

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Dont try this at home:

I got this off of a generator forum. Thought the theory of it all would be interesting.
Reference to a Salt Box Load Bank.

I used salt water. I took 1/2 an 55 gallon drum and mounted a post on each side with nails/notches to support a non-conducting crossbar at different heights. Two(or three) copper electrodes made from old pipe were attached to the crossbar, short enough so as not to touch the bottom of the drum. The power is fed to the two(or three) electrodes and the neutral is tied to the drum itself.
Fill the drum about 2/3 full of water, set the electrodes all the way down, turn on the power and add salt until you get the current you want. As the water warms the current will increase. Raise the electrodes to decrease it as necessary. When the water boils it will stabilize. I have had no trouble loading to maximum on a 15kw unit (62.5 A single phase).
As always be careful when working with exposed terminals that are hot both electrically and thermally.

Of course I only needed to dissipate 15 KW so I made a small one , but the principal is the same. Run it boiling, the heat is dissipated as steam and you just need to add makeup water. I had more electrode than I needed using 1 inch copper pipes about a foot long.
 
When I was a kid I wanted a window fan, but the motor I had ran too fast, so I made a salt water rheostat like yours, but way smaller, in series with the fan motor.
By the time the water boiled away the night air was cool enough that I didn't need the fan.
Very dangerous. . .
 
What's with this ?

What's with this ?

Has this forum lead ya'll to experimental theroies, I don't get it.

I mean sure it cool to wrap wire and measure and truely build something, IE assemble parts, and measure, but again this has all been done.
The results have long been published.
Hooking up transformers for fun, coils and now boiling salt water?

If you had a couple bushels of your favorite seafood fest, I'd undestand!

This practice of experimenting is far more dangerous then the satifaction of the results that are achieved...JMO.

OK, I just don't get it...

Now with a war on, the past few and the present congress have all but dropped all applications of basic science, which is sad...
 
Loadbank

Loadbank

Cadpoint, experimenting is what got us to where we are today. If Edison did not experiment perhaps no light bulb? Tesla, no three phase. I was taught in school that experiments prove the idea and theory.

Charlie
 
Its not my life or limb

Its not my life or limb

charlie k. said:
Cadpoint, experimenting is what got us to where we are today. If Edison did not experiment perhaps no light bulb? Tesla, no three phase. I was taught in school that experiments prove the idea and theory.

Charlie
Click to expand...

I don't disagree, with the blue comment.
I do beleive that some might be putting to much life or limb on the line.

I'll give you that the big dogs T & E, were in a controlled enviroment and where researching through the use of experiments
to proof or prove there theories, dedcutions, hunchs, or that 10%.

But what I've seen posted is well frankly, scarey...
 
Seems a shame to boil all that water and not throw a few ears of corn in.:grin:
 
cadpoint said:
I don't disagree, with the blue comment.
I do beleive that some might be putting to much life or limb on the line.

But what I've seen posted is well frankly, scarey...
Click to expand...

I tend to agree no matter how interesting I find the topic....

Having load banked some generators in some non-traditional ways before... I don't think I would be up for this one.... It's just one wet slippery slip from an arc flash under steaming water with any sizable generator. Not to mention the exposed voltages - in water inside a metal drum no less...

If looking for fun - why not against another generator, or better yet a few thousand light bulbs. Or something sillier but more fun - like a tesla coil under controlled conditions.
 
thanks for the post!!

thanks for the post!!

jrannis,

Thanks for the interesting post!

I downloaded the google pdf @ ~32MB!, and it's awesome! (TX winnie)
After just a quick read on the topic I saw this came out of a 1902 College book!
This was before they trailered a loadbank to the site, connected up with locking connectors, and dialed in the necessary resistance to test their systems!

There was reference to using an adjacent lake if you needed higher loadbank capacity!

A truly interesting read!

JM
 
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To be clear, I was not suggesting that a water rheostat would be a good way to build a load bank today. They are part of our electrical history, like live front panelboards and exposed knife switches.

(Though I recall visiting a motor research lab where they still had servo controlled water rheostats in their own room, ready for use if you needed an adjustable DC load.)

-Jon
 
This was the question!!

This was the question!!

Back in the seventies I worked at a boatyard. We overhauled small boats like the LCM,s and LCU's among others for the Navy, Army and the Corps of Engineers. The electricians there built a salt box load bank. It was a large wooden box lined with metal (maybe 100 gallon capacity) They made a metal grid which could be raised or lowered into the water to control the load with a small winch. Water was pumped through some coils to control the heat.
My questions: Where can I find some info and plans to build one ? Just what type metals are needed ? How much box and grid area are needed for X amount of kw's ? What about building one for three phase ? What amount of salt is used if any ? Is such a thing even legal to build and use ?
We presently have two load banks, one is 10 kw and the other is 100 kw. Sometimes we need to test larger generators and as you know load banks cost lots of $$$.
 
If one were to actually want to build a water rheostat load bank, I'd suggest looking through old books on the subject.

This is technology that was invented, refined, and then obsoleted. While it may very well have present day applications, I would not want to try and _reinvent_ the technology.

That said, it looks like someone has been busy reinventing: http://www.jazweb.us/sdsu_energy_lab.htm

Looks like Lindsay has a reprint: http://www.lindsaybks.com/bks9/danger/index.html

Some of the books that google has digitized show designs,
just do a books search for "water rheostat", and specify that you only want to look at results where the full book is available.

http://books.google.com/books?id=IDAKAAAAIAAJ&pg=PA109&dq="water+rheostat"&lr=&as_brr=1 paragraph 454 says 'there is always more or less risk of getting shocks when adjusting...'

Here is a 700KW 2.3KV three phase water rheostat design. They specify a running stream; I wouldn't want to be swimming anywhere nearby.... http://books.google.com/books?id=nGQ6AAAAMAAJ&pg=PA147&dq="water+rheostat"&lr=&as_brr=1

Have fun reading. If you actually build anything, you don't know me :)

-Jon
 
At one time, the Norfolk & Western RR had some electric trains out in western VA. I recall reading that the powerhouse in Bluefield used a steel ingot in the river as the ground point, and an adjustable grate in the cooling water canal as the "reject" load for when the trains were returning more to the system than other trains needed. I'll have to dig out the book on that, it's buried in the basement...
 
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