View Single Post
  #13   Report Post  
Posted to sci.electronics.repair
Franc Zabkar Franc Zabkar is offline
external usenet poster
 
Posts: 1,569
Default Electric fence "Electric Shepherd" ESB 250

On Thu, 1 Jan 2009 08:39:30 -0000, "N_Cook" put
finger to keyboard and composed:

Franc Zabkar wrote in message
.. .
On Wed, 31 Dec 2008 08:26:59 -0000, "N_Cook" put
finger to keyboard and composed:

Back working with proper bridged repair, new neons etc . I'm asuming 8KV

(it
is actually mentioned on the label) , at least it fires a neon via 100M ,
(0.1G ) dropper, I will dig out EHT divider today. The casing screws

mayvbe
UNC which may indicate USA but label has UK address. Electric Shepherd
printed on the PCBs


FWIW the following device has an open output voltage of 8kV.

Electric Shepherd ESB25 Battery Fence Energiser:

http://www.rutland-electric-fencing....px?ProductID=2
88&ReturnToListURL=PageSearch@2Easpx@3FProductSea rchText@3Desb25&ProductList
TypeName=SearchProductList,%20App_Code,%20Version =0.0.0.0,%20Culture=neutral
,%20PublicKeyToken=null&IncludeDealersOnly=False& ProductSearchText=esb25

I have an electric fence controller kit that works by charging a 7uF
"dump" capacitor to 340V and then discharging it into the primary of
the HV transformer. The energy stored by the cap is ...

E = 0.5 x C x V x V = 0.40J

Its output voltage peaks at 3.6kV.

The ESB25 is spec'ed at 0.08 Joules, so perhaps you can work out the
required capacitor voltage (= transformer primary voltage) as follows:

V = sqrt( 0.08 x 2 / C)

Assuming V = 110V, then C = 13uF.

What is the rated DC voltage of your dump capacitor, assuming yours is
a similar design?


All boxed up now but from my listing of major devices it is 20uF, 400V
Of course the 110V primary is now used as the secondary here, for th
evoltage step-up. Internal construction looked the same as mains
transformer.


Assuming that the energy output of the ESB250 is the same as the
ESB25, then I calculate that the charging voltage should be 90VDC.
This seems low for a 400V cap. Maybe you should enquire as to the
actual energy rating.

FWIW, the ESB15 energiser is rated at 0.05J:
http://www.rutland-electric-fencing....ro ductID=289
http://preview.tinyurl.com/9xkv7d

Rutland's recommendations seem inconsistent:
http://www.rutland-electric-fencing....malCattle.aspx

"As a very general guide, the energiser powering a permanent fence
should have a stored energy of not less than 0.5 joules for cattle
...."

"Dairy cattle being strip grazed can usually be contained with a
single conductor of poly wire or 12mm poly tape, powered by an
energiser of around 0.25 Joules or less provided the voltage on the
fence is around 2,000 - 3000volts."

BTW, if you ever need to source a replacement transformer, then maybe
you could consider an old Philips FBT of the type that required a
tripler. Those would have had an output of 8kV (25kV / 3), and the B+
would have been 155V or less.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.