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Complex design - electrical energizer for fencing

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Zar

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Hi all,

I am looking to build a very specific electrical fence energizer per client's request. I personally have a very very limited knowledge of electronics. I was hoping that I could gain someone's expertise on here in the circuit diagram and components needed. I will get a local professional EE to build this for me after I have consulted with him and then provide the necessary hardware. This has to be built to withstand excessive heat (upto 60 C), high humidity (99%) and in a high dust environment.

I have read a few post on electrical fences here and on other sites. But they are not close to the specs I am required for my client. I could have the local EE do this but I want to make sure that what is designed is accurate and safe but effective for the client.

Here are the specs:

Input: 220 VAC
Output: 12 VDC
Amps: 40mA (above 50mA will kill, so client just wants to give a very strong shock only but still being safe)
Pulse current of duration: 250ms
Pulse frequency: every 500ms
Max out: 10-15 Joules
Max stored: 20-30 Joules
Open circuit: 25Kva
500 Ohm load: 15Kva
100 Ohm load: 10Kva
Max operational temp: 50-60C
Max operational humidity: 99%
High dust environment
Unit will be housed in a theft/tamper proof enclosure outside
All connectors (+ & -) to fence will be 8AWG

- LED power indicators (Red - fault, Green - On, Amber - running on 12V battery backup power)
- Separate digital meters for: Current out, Voltage, Stored charge and Battery charge level
- When the unit is powered on, a delay of 15s before it is fully charged and ready so that a flashing light beacon and siren (light & siren externally mounted) can be used to make sure that no one is touching the fence after maintenance as a safety precaution (and yes, kind of like the fence in the movie Jurassic Park - the client got the idea from this movie)
- Area to be protected is approx. 40km

Again I would be most appreciative with assistance with this. I have to build, test this component before Oct 15th and demonstrate it to the client by Oct 30th otherwise I will lose this contract. :(

Please let me know if any more details are needed or questions that I can ask the client in order to build this energizer.
Again thank you to those who help and read this post.

- Zar
 
Hi Zar and welcome to the forums.

I believe you need to again sit down with the client and someone strong in electrical / electronic. While some of the clients request make sense some do not. Starting with the 220 / 12 volts DC. This is not going to do much of anything. For example my 12 volt battery in my truck is capable of hundreds of amps. However, if I grab both terminals using both hands I likely will not feel anything. If I place my hands in a bucket of salt water and while still wet grab the terminals I may feel a slight tingle of shock but really nothing and certainly not a deterrent. Pulsed DC electric fences use much, much higher voltage.

What the client is asking for could likely be designed and built, however, it would not do anything. Additionally an electric fence depends on how it is wired. There are numerous ways to go about that. There are a bunch more variables but pulsed 12 VDC will not do anything.

Just My Take
Ron
 
I'm not in a position to design this for you, but IMHO there are a number of issues with the spec which a competent EE would have to consider, among them :-
1) The output Kva figures look positively lethal (to me at least)!
2) What is the '12V' for? Recharging the backup battery? If so, it will need to be > 12V.
3) 40mA is too close to the lethal 50mA for safety and does not allow for different sensitivity of individuals to shocks.
4) 250mS output seems an excessive duration.
5) What output voltage is required? The Kva figures are power values.
6) The figures for Joules are inconsistent with the Kva figures.
7) At 99% humidity, many units spaced along the 40km will probably be needed to counter leakage to ground.
 
I think the input is 220ac and or 12dc.
The output is 25kv no load and 15kv and 10kv under load.
In many countries a fencer can not run 100% on. They can be on for 0.5 seconds then must be off for 2 seconds. (better check those numbers but I know not 100%) {I just looked in a manual, it is on for 150uS and off for 1 second.} If you build this and it kills a child, and you did not follow safety laws, you will not post on this forum for 50 years to life.
 
on for 150uS and off for 1 second
That seems more reasonable.
you will not post on this forum for 50 years to life.
Don't prisoners get internet access these days? ;-)

I hope you've got good liability insurance if you take this contract, Zar!
 
I think your client needs a reality check. He's asking you to design, build, test and deploy a new fence changing system in a little over a month. I need business too, but I wouldn't accept a fool's errand.

I'd suggest you find a commercial unit and sell it to him at a huge price markup.
 
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10kV into a 100 ohm load is 100 amps. That's somewhat is excess of the 40mA limit. :eek:
 
As said before. The specs are goofy and don't make sense.

Kva isn't even a real abbreviation. kVA is for Kilo-Volt-Amps

Now, is an environmental enclosure necessary? Vortex cooler (uses air) or thermoelectric? These are expensive.
 
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