The Final Frontier
dramatized by Cynthia Waters
In August of 1980
in the southeast United States, problems were being experienced
at a polypropylene plant. Strange things were happening around
a film slitting machine.
David Swenson of
3M Electrical Specialties Division in Austin, Texas was called
in to investigate. Little did he know that he was about to enter
the final frontier. When Dave asked what type of problem they
wanted him to look at, he was told that he would have to come
to the plant. They could not explain it over the telephone. They
did tell him that they were experiencing problems with contamination
of wide web film as it was being run at high speed, converted
(split) into "film jumbos" with a width of 3' x 5' for
coating with adhesive to make tape. Dave didn't see what was so
unusual about film being contaminated by dust, flies, other insects
and... birds. "Birds"?
Now they had Dave's
attention and he didn't hesitate to go to the plant to see for
himself how birds could be caught up in film.
web was 21 feet across - almost the width of three lanes of traffic
on the interstate. The film ran from one roller up 20 feet
to another roller; across 15 feet to a third roller; down 20 feet
to a splitter; and was then wound onto two rolls. It formed a
huge dynamic "tent". On the morning that Dave intended
to measure the static electricity inside the web tent , the temperature
was 80°F with a relative humidity of 75 to 80%.
As he walked toward
the web with his field meter in hand, the machine operator said
"I wouldn't do that if I were you. Strange things happen
inside the web tent this time of day."
Dave paused and thought
about what the man had said but he was there to do a job and that
was what he intended to do. You see, Dave is a very brave guy.
Besides, it was just film running on a splitting machine. He had
seen that many times and nothing seemed particularly unusual that
morning. That is, until he looked down at his static field meter.
With a 200kV @ 12"
measurement device, the voltage measurements were off the scale
and he was still 20 feet away from the web! For the meter to be
pegged at that distance, the amount of static electricity had
to be in the Megavolt range. He thought to himself "Van de
Graaff would be proud!"
Since he had come
this far, Dave decided to enter the web anyway. As he did so,
the hair on his head, arms and entire body began to stand on end.
Even worse, he began to feel like sparklers were hitting him all
over his body. It felt like burning sensations at hundreds of
points all over his being. (brave? - hummm?) At exactly one-half
way into the web, David slammed into a wall that was both invisible
and impenetrable. It felt like he had hit a force field like he
had seen on Star Trek.
Although he knew
this was Coulomb's Forces - the law of static attraction and repulsion
- he was held in place for what seemed like ages as he tried to
grasp what was actually happening to him. It's one thing to know
about Coulomb forces, but it is quite another to feel them with
such gusto. When he finally came to his senses, he had to literally
"peel" himself off of the invisible wall.
As he backed out
of the web, he saw a fly drawn right up into the film and wondered
if conditions ever existed inside that web that could actually
draw a person up there as well. Dave hurried to talk with the
Plant Manager and excitedly explained what had just happened to
him. The Plant Manager agreed to go to the web to see for himself
what was going on. By the time he was able to go, however, it
was later in the day and the temperature and relative humidity
had risen. He was able to walk into the web and from one side
to the other without experiencing anything at all unusual. He
told Dave that he thought he was simply hallucinating. When the
machine operator corroborated Dave's story, the Plant Manager
agreed to meet early the next morning to see if the same conditions
would exist as they had experienced earlier in the day. They met
bright and early the next day. As the Plant Manager entered the
web, his curly gray hair immediately straightened. As he strutted
toward the center of the web, his confident gait suddenly came
to a complete stop as he hit the wall of invisibility.
Once he peeled himself
off of the force field wall, a shaken Plant Manager came out of
the web and exclaimed...
that he "didn't
know whether they should fix it or sell tickets".
They decided to fix
Static Electricity can cause some very strange and often difficult
to explain phenomena. It is easily controlled if a commitment
is made. This nuisance can be reduced to a non-nuisance level
by proper analysis and installation of suitable equipment, at
a very low cost.
An induction static eliminator was installed across the web at
the unwind. The static electricity was immediately reduced throughout
the process to less than 50kV (from MV's). It was then possible
to make measurements in the rest of the area. Additional induction
units were also installed at the jumbo wind-up areas which resulted
in less than 5kV at conclusion.
We would like to hear your explanations for Dave's adventure.
Please give us any similar experiences you may have had. We will
publish these in the next issue. Maybe this will become a series
- "Weird Phenomena."
via e-mail September 22, 2001 from reader Melissa Georgiou
I was searching the
internet to find a similar situation that I had encountered and
your article on the invisible wall is very interesting. I encountered
an invisible wall, but it felt more like a cushion which was vertical
and got denser the farther I pushed on it. It lasted for about
30 secs and I could not walk through it. It happened at dusk in
England during fog and high sunspot activity. I've been trying
to explain it since. I am so glad some one else has experienced
a "star trek" like force field and I hope you will encourage
your engineers to perfect the effect instead of fixing it by decreasing
via e-mail June 7, 2001 from reader Peter Thomson
EUREKA - I have found
it. I have been studying the implications of charge being moved
at high speeds. The math is very complex so it is hard to predict
what sort of experimental setup is required to demonstrate different
aspects of the phenomenon. But I think your members have practical
experience of this phenomena, and my theory may provide insight
into practical ways of predicting and preventing problems.
First, a little bit of basic physics,
often overlooked. When you consider two charged particles with
the same charge, when stationary they will repel each other, but
when moving in parallel each moving charge creates a circular
magnetic field round itself that results in mutual attraction.
This is normally demonstrated in the attraction between two wires
where negative charge is moving in parallel, but applies equally
to charge moving in a paper or plastic film on a production line
or in a moving charged dust cloud, or a thunder storm.
The forces created by an electrical
current in a wire are produced in proportion to the speed of electrons
through a wire. Because of collisions and random movements of
electrons in the wire, the overall speed of the electrons, or
drift speed is quite slow. http://hyperphysics.phy-astr.gsu.edu/hbase/electric/ohmmic.html
(but the density is high). A 1 volt potential in a pure copper
wire will produce a drift speed of 0.0043m/s This is less than
half a centimeter in a second. One definition of the amp and force
is based on this. 1 amp produces a force of 2*10^-7 Newtons per
metre of wire when the parallel wires are 1 meter apart. By contrast
production line speeds for paper and plastic film can be over
100 times faster and air flow in a tornado can exceed 1000 m/s.
Because electrostatics and electric
current are often taught separately in schools, the effects of
moving charge are often forgotten about. The effects of moving
single charge become most dramatic when a charged vortex is created.
Charged particles in front of or behind another particle will
experience strong forces of repulsion, but the charged particles
moving in parallel are very strongly attracted together! The net
result is to form a charged sheath vortex, where a sheath of particles
rotates about an open core. The sheath cannot contract into the
core because of repulsion round the core, and the opposite sides
flowing in opposite directions repel, Neither can it expand outwards
from the sheath because of the attraction between particles moving
in parallel. The result is a very tightly bound sheath of particles
and air molecules. If new charged particles are being delivered
to this rotating sheath vortex they will be bound into the sheath
with the build up of huge electrical potential that doesn't discharge
because of the forces of attraction generated by the movement
of charged particles.
Your article describes the ideal
situation for setting up a charged sheath vortex. The high speed
web is delivering a constant supply of the same charge to the
tent created by the web flowing up and over the tensioning rollers.
Within this tent, friction with the moving film causes the air
to start rotating and initially this air will be given the same
charge as the film. The rotating charged air will now start to
create the attractive forces between particles moving in parallel
and will draw in more charge from the moving plastic web. This
process will continue and will produce a charged vortex sheath
spinning in the middle of the tent. This would normally be invisible
and could also feel like a solid wall with a well defined edge
(and a soft center). You certainly wouldn't push it out of the
The charged sheath vortex could
be made visible by releasing smoke streamers into the area.