Re: Pole Pigs

To: tesla-at-pupman-dot-com
Subject: Re: Pole Pigs
From: Bert Hickman <bert.hickman-at-aquila-dot-com>
Date: Sat, 23 Nov 1996 08:44:48 -0800
Tesla List wrote:
> 
> >From scottb-at-aca.caFri Nov 22 20:30:29 1996
> Date: Fri, 22 Nov 1996 15:38:36 -0500
> From: scottb-at-aca.ca
> To: tesla-at-pupman-dot-com
> Subject: Pole Pigs
> 
> What is the benefit of going up to a pole pig??  Do you hook it up to the
> mains before they enter your house??  are they used when you want your
> primary side of the step up transformer to draw more than 15 amps??
> 
> /sb

Scott,

There are numerous benefits:

1. A pig is virtually indestructable. A pig's built-in insulation system
withstands repetitive voltage and current transients that will toast
neons. 

2. Although a pig requires a way to externally limit current
(ballasting), this permits a coiler to more easily optimize his overall
system by separate adjustment of the inductive and resistive portions of
the ballast.

3. A pig is more convenient than groups of neons when running at higher
power levels.   

4. Pigs can be intermittently be overloaded to 1.5-2X their faceplate
rating without even getting warm.


There are also numerous disadvantages:

1. Pigs require a more robust sparkgap, typically a rotary, to "force"
the gap to break

2. Pigs require external inductive/resistive ballasting

3. Pigs are big, heavy, and fairly costly. A 10 KVA pig typically costs
$300 and weighs 300+ pounds, and most are oil-filled. Used neons can be
obtained cheaply/free, and are much more portable.

4. Larger capacitance may be required to efficiently use the additional
power available from a pig. Groups of home-made caps can be used, but
the sheer number required begin to cause interconnection inefficiencies.
This drives most serious coilers to purchase commercial pulse
capacitors.

5. Pigs require _serious_ power control/safeguards. They are capable of
delivering massive short circuit currents and hot flaming arcs.

Pigs are typically run from 240 volt power, through a dedicated circuit
breaker in the house breaker box, never directly off incoming service.
Power level is controlled via inductive and resistive ballast (typically
a short-circuited 240 Volt AC welder), and a variac. In addition, Power
Factor Correction (PFC) capacitors, EMI filtering, and power
contactor/interlocks are typically used to help protect OTHER equipment
in your house. 

Most coilers start with neons, and increase power by simply connecting
more in parallel. If you cultivate cheap/free sources of used neons from
local sign shops, you can more easily accept their inevitable death.
Going to a pig is a _much_ larger commitment, both dollar and
space-wise... think long and hard before proceding.

Safe coilin' to ya!

-- Bert --