Author Topic: Dump load (Read 7431 times)

wellusee · « **on:** September 02, 2009, 03:18:37 PM »

I was about to buy the heat element for the Morningstar TS60 but they are difficult to get in Ireland .My supplier suggested to go for a heater. Can anyone tell me what is the best or the recommended dump load heater for the 24 Volt stator on the 10' diameter turbine?

Wellusee.

SparWeb · « **Reply #1 on:** September 02, 2009, 09:33:11 AM »

Hi Welcome to the forum.

I think that was discussed a couple of times not too long ago. Have you searched the board? The "Google search" should turn up quite a number of hits if you ask for "dump load" or "diversion load".

wellusee · « **Reply #2 on:** September 02, 2009, 09:50:14 AM »

Hi , Ilooked to see what products Morningstar have . They have an element (24Volt)which is fine and I intended to burn off excess power that way beside the turbine. Then this idea of a heater comes up which I could use in the house . So I suppose I'm looking for a DC 500 Watt heater .

Thanks for the comments.

Wellusee.

Flux · « **Reply #3 on:** September 02, 2009, 09:56:08 AM »

For a 10ft machine you may expect peaks up to 1000W so you need a load to dissipate about 1000W at 24v.

You may be able to get special heaters but I don't think you will get an off the shelf solution, it may be very costly to get a special.

You need something just over 1/2 an ohm. You could use several of the wire wound 300W resistors from Farnell if you don't want to heat water and connect them in parallel.

Four 2 ohm ones in parallel would do the job ( 2.2 may be nearest preferred value).

If you want to use heaters then it will take a fair number of 240v ones in parallel. I doubt that you could get 110v ones in Ireland but you would then need less.

Flux

Flux · « **Reply #4 on:** September 02, 2009, 10:01:19 AM »

If you really want a water heater it may be cheaper to buy one special expensive one than use a load of 240v ones in parallel.

A 3 kW 240v heater would take 1/100 of that at 24v, something like 30W but perhaps a bit more depending on the resistance coefficient with temperature.

Flux

Volvo farmer · « **Reply #5 on:** September 02, 2009, 11:29:58 AM »

I recently built one of these out of old electric dryer elements.

I started with a couple of these out of GE dryers, and a couple WE11x61 restring kit (about $12 ea) and ended up with what you see below. I am unsure if I am going to install a fan in the front of the box or not, but it was pretty easy to tweak the wire lengths to end up with .6 ohms.

Hope this helps

galeforce jones · « **Reply #6 on:** September 02, 2009, 01:17:04 PM »

Here is a link to a dumpload that is suitable for your requirements

http://shop.ebay.com/i.html?_trkparms=65%253A12%257C66%253A2%257C39%253A1%257C72%253A1205&_nkw=d
iversion%20load&_trksid=p3286.c0.m14&_pgn=1

galeforce jones · « **Reply #7 on:** September 02, 2009, 01:19:58 PM »

sorry wrong link, this is the correct one

http://cgi.ebay.com/35A-24V-1000-Watt-Diversion-Dummy-Load-Resistor-Heater_W0QQitemZ150365852504QQcm
dZViewItemQQptZLH_DefaultDomain_0?hash=item230280d358&_trksid=p3286.c0.m14

wellusee · « **Reply #8 on:** September 02, 2009, 04:23:53 PM »

Thanks for the link.

Wellusee.

wellusee · « **Reply #9 on:** September 02, 2009, 04:39:36 PM »

This looks very good . How is it working for you ,I assume you have the 24volt stator in your turbine? Here in Ireland our appliances run on 220 volts AC.

What I think your telling me is if I get the resistance down to under about 6 homes it will take the load. Thanks for loading the photos. I'd rather build something than buy it as I've built the turbine.

Thanks

TomW · « **Reply #10 on:** September 02, 2009, 04:53:41 PM »

Jonesy;

Damn that thing sells for about 20X what a dump load is worth.

I suggest he look up Ghurd and others here for something sane to use.

Just my opinion.

Some folks love to burn cash.

So, jonesy, are you the seller or what?

Please share why you think it is a good option for a dump load?

Since you joined the forum today and these are your only 2 posts it is reasonable to wonder why you posted this?

Please do not use this forum to pull in bidders to Ebay if you are the seller.

Tom

bob golding · « **Reply #11 on:** September 03, 2009, 05:34:42 AM »

you could use the elements from old electric storage heaters. i have used those in the past. they pop up on freecycle quite often. plus you also get a load of bricks as well.

bob golding

TomW · « **Reply #12 on:** September 03, 2009, 06:23:37 AM »

bob;

I have several friends who are potters. Their electric kilns use a coiled length of nichrome wire. If they burn out it just burns in one spot and opens. I get their dead element pieces.

It seems expensive new but useless if too short and they don't splice well. The shorter lengths are perfect for rigging up nearly any size low voltage dump load with a little DIY effort and are no where near $150 a KW.

Just another cheap / free source for dump load elements if you can do some fabrication. And it is recycling at its finest. Junk to useful device is tough to beat for cheapskates [err recyclers] like many here.

Tom

bob golding · « **Reply #13 on:** September 03, 2009, 06:33:07 AM »

tom

i use the centre metal bit from terminal connectors to connect the bits together. works fine. the nichrome wire does go brittle when it is old so as you say it is dificult to splice.

bob

wellusee · « **Reply #14 on:** September 03, 2009, 12:47:04 PM »

You're right on that. The original water elements (need2 2) will cost me 616 euros or $875 that is a bit rich for me. Could I use a number of 24volt bulbs in parallel to get the 40 amps required. I know the dumped load would go into a light show but at least the batteries and turbine would be safe.

Wellusee.

wellusee · « **Reply #15 on:** September 03, 2009, 12:52:59 PM »

Hi Volvo, Did you get to make it to take the 40Amps ?

Wellusee.

TomW · « **Reply #16 on:** September 03, 2009, 01:23:51 PM »

usee;

Many folks do not think bulbs are reliable enough for this application. It would "work" but if a bunch are in parallel and they start to blow then the others get driven harder etc etc. leading to either no dump load or insufficient load.

Just whats been mentioned before about bulbs as dump loads.

Tom

Volvo farmer · « **Reply #17 on:** September 03, 2009, 02:21:32 PM »

Sorry, it will likely not be tested for several more weeks.

hydrosun · « **Reply #18 on:** September 03, 2009, 02:43:26 PM »

I've just used old 120 volt heaters in metal cases that have the coiled nichrome wires. I connect heat resistant wires to a couple of spots on the wire to get several parallel lengths of nichrome. For a 1200 watt heater at 120 volts, resistance of 12 ohm connected with 3 wires at the 1/4, 1/2 and 3/4 points will have 4 lengths of 3 ohm for a total of 3/4 ohm. At 28 volts it will use 37 amps, just over 1000 watts. I straighten out a short length of nichrome at the attachment point, sand it clean, twist the copper wire with it and crimp a tube connector over both. I bring the end of the copper wire out of the hot portion of the heater to connect all the parallel wires to the positive and negative input wires. I've used a few of these as dump loads for hydro systems. A heck of a lot cheaper than the ones I've seen sold for diversion loads. And some of those didn't have a cover on top making them a fire hazard from things falling onto the heating elements.

Chris

wellusee · « **Reply #19 on:** September 03, 2009, 03:25:05 PM »

Hi Bob,

I have sent scouts out looking for these heater coils. Here in Ireland people are very good at recycling so everything like that goes to the local Co. Council. They don't approve of people scavenging for parts. So we'll try the shops before they dump them.

Paddy.

wellusee · « **Reply #20 on:** September 03, 2009, 03:29:39 PM »

Hi Tom.

Thanks for that. I'm new here, finding my way around the site. Where did you read about this?

Paddy.

wellusee · « **Reply #21 on:** September 03, 2009, 03:45:50 PM »

Hi Chris

You know your V's from your W's any chance of a photo of your finished product?

Building the turbine stator n all seems now to be the easy part!

I'm getting good help here plenty of people with ideas .

Paddy.

TomW · « **Reply #22 on:** September 03, 2009, 03:55:41 PM »

usee;

I read most of it right here on this forum.

Well, as is often pointed out Google is your friend.

Click

HERE

Enter "dump load" You will find a few days / weeks of reading about them.

Seems someone suggested Google earlier but so few folks take the time to look for it themselves.

Tom

zeusmorg · « **Reply #23 on:** September 03, 2009, 06:08:54 PM »

Nichrome wire can be found in just about ANY electrical appliance that produces heat.

Toasters, counter ovens, stoves (inside the ceramic heating elements) electrical baseboard heaters, electric clothes dryers, the list goes on.

Anyone that is good at recycling things for other uses could find some of this stuff.

All you need to do is find an appropriate length for the resistance needed. More can be added.

ghurd · « **Reply #24 on:** September 03, 2009, 06:37:43 PM »

Capt Slog reworked a 3KW 220V UK heater.

It is for 12V, but the principles are the same.

And he took pictures.

http://www.fieldlines.com/story/2007/8/30/8538/81113

G-

galeforce jones · « **Reply #25 on:** September 04, 2009, 10:19:47 AM »

Hello Tom

I should have introduced myself properly as these were my 1st posts, I live in Ireland, I have been visiting this form for the past 18 months or so and read so much helpful information. I would like to thank flux especially and look forward to reading his posts. I have built 3 wind turbines, a mixture of hughs and otherpower turbine designs. One is 1.2m and the others are 2.4m and are up and flying, im pleased with their performance and how quiet they run.

I have never sold anything on ebay but I have bought parts for my turbines on ebay eg. 3 phase recifiers, panel meters, charge controllers and dump loads, I find it a good source for parts and information. I have not found good and safe information on building DIY dumploads. I used a ohmite 1 ohm 1050w resister and a tristar 45 controller which i got on ebay. I for one do not have money to burn, on the contrary, I try to keep spending to a minimum. I suggested this link for a dumpload because there is enough information on how to size and put together a dumpload if you could not afford to buy one. I will try to upload pictures in another post.

Michael

TomW · « **Reply #26 on:** September 04, 2009, 12:48:20 PM »

Michael;

Sorry, no offense intended.

We get a lot of that kind of thing being a well known RE centric board.

I guess its part of the deal as an editor to keep an eye out for inappropriate use.

It is internet profiling thing. Someone joins and posts links to ebay or their other for sale item, gimmick or whatever as their only posts just looks suspicious.

Welcome to the board and hopefully you understand the reasons for my asking those questions.

Yes, Flux is a veritable goldmine of information and he shares freely. Can't beat that.

Again, welcome to the board.

Tom

Ungrounded Lightning Rod · « **Reply #27 on:** September 04, 2009, 02:40:18 PM »

Also: Light bulbs have a MUCH lower resistance when they're off and cold than when they're on and hot. This means your controller has to switch FAR more current turning them on than it would with a resistor that doesn't heat up as much. So you have to oversize your controller by a "factor of several" or it will die when you need it most.

Hilltopgrange · « **Reply #28 on:** September 04, 2009, 02:53:16 PM »

Have a look at here http://www.thebackshed.com/Windmill/articles/200wDumpLoad.asp about as good a guide as you will find! hope it helps

Russell (Co Down)

ghurd · « **Reply #29 on:** September 04, 2009, 03:24:32 PM »

I wish I could convince people of that,

and that light bulbs don't last nearly as long as resistors,

and that resistors for small scale can cost about the same per amp as bulbs.

I feel there are some other issues with bulbs too.

Example #1: PWM type controller, or even my controller.

The controller kicks on the load for a couple milliseconds and dumps a lot of amps.

When it needs to dump more amps, the Pulse Width is wider, so the bulb heats up, and the bulb dumps less amps.

It can dump less amps when it needs to dump more amps.

Example #2A: Not really an example. More like experience and a feeling?

It seems a light bulb has a life expectancy inversely related to the number of cycles it has experienced.

Example #2B1: I smoked a big square car head light in 30~45 minutes testing fets at a fairly high Hz for the prototype 'ghurd controller'. The little #1156s last a lot longer than head lights, but they cost more per amp.

Example #2B2: Price the sockets for small bulbs. They cost more than resistors!

I solder wires to the small bulbs, but it's a PITA, it will be a recurring PITA, and suitably mounting the bulbs is a PITA.

That's more pitas than a Greek restaurant has.

G-

windspeed · « **Reply #30 on:** September 04, 2009, 04:27:16 PM »

I live on the west coast of Ireland

I have been useing a home built dumpload for a 18 months plus

comprises of deisel heater plugs (connected in parralel to give suitable load) mounted in a 1" copper tube set up in a thermosyphon arrangement

all parts are easy and cheap to come by

I am pretty sure this system can be used to heat domestic water reasonably efficiently though I have not tried it yet

Windspeed

ghurd · « **Reply #31 on:** September 04, 2009, 04:49:43 PM »

If this system is one I had email photos of, it would be worth a post.

I may be thinking of another similar system.

My email is not organized.

G-

Ungrounded Lightning Rod · « **Reply #32 on:** September 04, 2009, 05:53:46 PM »

I would not use diesel plugs to heat water that would end up in the house taps. They're not rated or intended for drinking water and may contaminate it.

Might be OK for hot water radiators or a hydronic floor system.

News:

Author Topic: Dump load (Read 7431 times)