PORTABLE EQUIPOTENTIAL PLANE FOR STRAY VOLTAGE REDUCTION

NATTES PORTATIVES ATTENUANT LES TENSIONS ELECTRIQUES VAGABONDES

English Abstract

Abstract
There is disclosed a passive stray voltage reduction device
comprising a wire-mesh inserted in a rubber or plastic mat.The
wire-mesh is connected to a conducting object,the conducting
object being in contact with all metallic structure which an animal
might contact.
Those mats are fixed under the animals (for examples, cows,
pigs,...).
The device is used to reduce stray voltages in grounded farm
equipment to reduce harm to farm animals.

Claims

The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows:
1. A portable equipotential plane inserted in a rubber or
plastic mat.
2. The device according to claim 1,wherein said equipoten-
tial plane is able to reduce or eliminate parasitic or stray
voltages.
3. The device according to claim 1, wherein said equipotential
plane is made of metal wires connected together and spaced
not more than 2 inches apart. (e.g.,wire-mesh).
4. The device according to claim 1, wherein said equipotential
plane can be made of a metal plate.
5. The device according to claim 1 must be covering the
major part of the mat.
6. The device according to claim 1, wherein the said mat is
made of rubber or plastic.
7. The device according to claim 1 must be connected to all
conductive objects which the animal might contact.
8. The device according to claim 1, wherein said equipotential
plane is electrically conductive.

Description

The present invention relates to an eguipotential plane for
parasitic or stray voltage reduction.
Stray or parasitic voltage is a small voltage that can be
mesured between two possible contact points, an electrically
grounded object and a ground reference.
When high voltage electrical equipment, such as distribution
transformers, are connected to the ground, the ground may offer
resistance causing the connection to the ground to have an
electrical potential above or below normal ground reference. The
same e~fect can be noticed even with medium voltage electrical
equipment such as electric motors used in farm machinery (e.g.
millcing machines). In this case, objects which are connected to
the same ground as the high or medium voltage electrical
equipment will have a ground reference which strays from normal
ground reference.
The stray or parasitic voltages are generally alternating and lie
roughly in the range of O to 15 volts. When conductive farm
equipment is connected to the same ground as the high voltage
electrical equipment, a farm animal coming into contact with the

X~7
farm equipment may be subjerted to parasitic voltages harmrul to
the health and productivity of the animals. A more in
description of the problem may be found in US pat~ ,355,595.
Many possible solutions for detecting and reducing such
voltages have been proposed as indicated, ~or example, by an 9 o l ,~ Z
article authored in 1978 by William Fairbank et al and entitled
"Milking Parlor Metal Stmcture-To-Earth Voltages",and by
another article authored in 1978 by R.D. Appleman and entitled
"Neutral-To-Ground Voltage Problems With Dairy Cows" and also
by an article authored in 1979 by L.H. Soderholm and entitled
"Stray-Voltage Problems In Dairy Milking Parlors".
One solution which has been widely attempted is to electrically
bond all electrical units (e.g., motors and controls) and all
conductive components (e.g., pipes, feeders and stalls) of the
system directly back to the earth ground at the electrical service
entrance. This makes all electrical units and conductive
components reside at virtually the same voltage as the neutral
conductor but does not eliminate different voltages from the
various units and components to different earth points. Thus, the

voltage to earth from the neutral conductor and a connected
component at one earth location can be diff~rent from the voltage
to earth from the neutral conductor and a connected component at
another earth location because of the resistance of the earth
between grounding points.
The object of the invention is therefore to provide an
inexpensive portable equipotential plane which will substantially
reduce or eliminate the latter voltage dif~erentials.
According to the invention, there is a passive stray voltage
reduction device comprising an equipotential plane inserted in a
rubber or plastic mat. The equipotential plane or mat is layed
down on the floor under the animal and connected to all
conductive equipment near the animal.
If the mat and all conductive structures which the cow, for
example, might contact with her hooves and with different parts of
her body are at the same potential, stray current wili not flow
through the animal.
The invention will be better understood after the following

description of the pre~erred embod;ment with reference to the
drawings in which:
Fig. 1 shows a portable equipotential plane inserted in a rubber
or plastic ma~.
Fig.2 shows the animals on a portable equipotential plane.
As shown in Fig. 1, an equipotential plane 2 can be made with
metal wires connected together and spaced not more than 2 inches
apart (e.g.,wire-mesh). The equipotential plane can be made of a
metal plate also. The equipotential plane 2 is inserted in a rubber
or plastic mat 1.
One or many wires S, being in contact with the equipotential
plane 2, pertrude in order to be connected to any metallic structure
which the animal might contact.
As shown in Fig.2, the animals are standing on a portable
equipotential pLane 2 inserted into a mat 1. The equipotentic
plane 2 in the mat 1 is connected to the metallic stnlcture 3 which

the animals might contact. The metallic structure 3 is connected
to all metallic parts ~e.g., milk tube 7, rnetal water pipe 6, metal
stall pipes 8,...). An animal could, while standing on the floor 4
of
a farm building,in the absense of equipotential or mat 1, sense
stray voltages exceeding a given sensitivity threshold when it
comes into contact with the conductive object 3 carrying the stray
voltages. The mat 1 eliminates or reduces the stray voltage that
the animal does not perceive when in contact with object 3 and the
mat 1. The voltmeter 9 shows no voltage from pipe 6 to mat 1.
The invention operates in the immediate environment where
the suppression of stray voltage is required, such as in the stable
or in the piggery shown in Fig.2. The mats of the invention can
be installed in any farm building to prevent harm to the cmimals.
Installation of one or many equipotential mats according to the
diagrams can be affected without necessitating any changes to the
farm building in which those mats are installed.

Representative Drawing