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simple dump load box
By otp9999zz, Section Controls Posted on Mon Dec 08, 2008 at 06:43:52 PM MST
rfgerge

Want to build a simple dump load with large resistors and no other frills or electronics other than absolutely needed. Was looking for a plan and a source for those Big DC resistors......500 - 2000 watt turbine outputs..

simple dump load box | 9 comments (9 topical)

Re: simple dump load box (3.00 / 0) (#1)
by electronbaby on Mon Dec 08, 2008 at 12:02:18 PM MST

If you want to build diversion load controller circuitry, I would have a look at Hugh's website, or talk to Glen (Ghurd) on this forum. Both circuits work well.

As far as the resistors, I have some kickin around my shop I might be able to part with, of course I would have to fine them. If time is of the essence, I would have a look on Ebay.

It is important to size the resistors for the maximum amount of power you will see from the turbine (and in most cases, 25% higher for a factor of safety) The controller and wiring then would be sized for the capacity of the resistors. The battery fuse for your dump circuit must be sized at to not blow unless of a short in your circuit. This usually means you will increase the size of your wires to exceed their voltage drop requirements.

If you have latency in the controller, you may want a higher factor of safety to be on the safe side. The best way around this is to not have a great amount of latency at all. Things will run more smoothly for you.
Have Fun!! RoyR KB2UHF

Re: simple dump load box (3.00 / 0) (#2)
by ghurd on Mon Dec 08, 2008 at 12:30:21 PM MST

Like Roy says, need to know how many peak amps it will make.
About any DIY dump circuit can be scaled up almost without limit.
There is a big amount of play in your 500W to 2000W.

Be careful with buying random resistors. It can get expensive for items not suited to your circuit or voltage.
G-

Ghurd.info

Re: simple dump load box (3.00 / 0) (#3)
by elt on Mon Dec 08, 2008 at 12:50:12 PM MST

Yes, ebay... I use a dozen of these
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=160270256369
The numbers you need will depend on your mill; check the seller's store for other values.

Hope that helps,
- Ed.

Re: simple dump load box (3.00 / 0) (#4)
by ghurd on Mon Dec 08, 2008 at 12:55:46 PM MST

Kind of pricy for a 12V system.
I have resistors too. Considerably cheaper per 12V dump amp, if shipping is included.
Figured I'd mention it.
G-
Ghurd.info
[ Parent ]

Re: simple dump load box (3.00 / 0) (#6)
by elt on Mon Dec 08, 2008 at 04:56:00 PM MST

Well yes, you website has some nice prices for a a couple hundred watts of resistors.

For me, I'm collecting toaster elements and nichrome wire for the next big dump load (like suggested farther down the page.)

- Ed.

[ Parent ]

Re: simple dump load box (3.00 / 0) (#5)
by zeusmorg on Mon Dec 08, 2008 at 02:23:23 PM MST

A dump load can easily be constructed out of nichrome wire, and can also be used for space heating with a fan used.

http://www.heatersplus.com/nichrome.htm

Has all the information you need to build one. They also sell all the components necessary (although you can find these components elsewhere and I do not associate or even advocate buying your materials from them, it just has the information needed)

With a nichrome heating element and ghurd's dump load controller, you can be in business for > $50.00 easily. The nice thing about using nichrome wire is you can size your resistance element to your own personal needs.

Re: simple dump load box (3.00 / 0) (#7)
by otp9999zz on Mon Dec 08, 2008 at 05:49:41 PM MST

is that nichrome wire suitable for DC...I heard there is an important difference in AC and DC resistors.. your average stove element wont work with DC,no????
anybody know why.???

[ Parent ]

Re: simple dump load box (3.00 / 0) (#8)
by zeusmorg on Mon Dec 08, 2008 at 06:37:12 PM MST

Yes that nichrome wire will work for d/c or a/c.. And yes a stove element will work with d/c power.

[ Parent ]

Re: simple dump load box (3.00 / 0) (#9)
by ghurd on Mon Dec 08, 2008 at 06:39:50 PM MST

They work fine.
The usual problem is the lower DC voltage.
A 1200W 120V heater or resistor only uses 12W at 12V.

Ohm's Law and Watt's Law.
G-
Ghurd.info
[ Parent ]

simple dump load box | 9 comments (9 topical)

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