Patent Application
20050212525
The present invention relates to a 24 hour all year round monitoring system of short and long term neutral to earth voltage events and allows an expert in mitigation of these events remote access to the monitoring system in both real and post time and securely.
Animals often have very much lower epidermal electrical resistances than humans. Consequently they are very sensitive to low electrical currents. Dry human skin is often over 10 million ohms whereas the epidermal surfaces of cows are often less than 400 ohms. Consequently cows feel low electrical current as we would if we placed our tongue across the terminals of for example a 9V battery.
This sensitivity to very low amounts of electricity has lowered productivity and the health of farm animals. It has also damaged the health of non farm animals such as horses and fish. Some dairy farmers have lost their livelihood because of short and long term duration Neutral to Earth Voltage referred to from here on a NEV. The term stray voltage covers NEV as well as animal contact voltage which is also called tingle voltage. The device of this current invention also may measure stray voltage and tingle voltage.
Animals feel electrical current. However as they have an electrical resistance measuring voltage will indicate the presence of current by Ohm's Law. Using an advanced high speed oscilloscope to measure voltage the events captured have specific signatures which an expert will read and interpret. These signatures offer vital clues as to the origins and ultimate remediation of damaging NEV.
When cows are milked their teats are connected to milking machines and as the milk flows from them it may form a direct path with the utility neutral as the stainless steel milk line pipes which carry this milk is bonded at the electrical service panel to the neutral. In North America the farm's secondary service neutral is connected to the utilities primary system neutral. Cows across North America and in other parts of the world are in contact with electric utilities neutral lines.
In the 1970's work was carried out to help reduce animal contact with the utility neutral. On dairy farm milking parlours copper and steel equipotential grounding grids where installed in freshly poured new concrete parlour floors. This helped equalize animal contact voltage and did reduce NEV exposure to animals.
However these grids may not have been adequately installed or may have broken up over the years leaving areas where animal contact NEV occurs. Also when cows entered and left the parlours as they stepped in and out of the equipotential grounding grid they experienced NEV. This was often enough to affect their milking and milk out rates and could lead to forms of mastitis and sickness in the herd.
These grounding grids often actually attract electrical currents to the milking parlours. As they have a low electrical resistance electrical return paths may find their way to it. During milking this may be painful to cows and long and short term NEV may enter them due to the differentials in electrical resistances between various places on the farms wiring circuits. In summer ground rods may dry out and their electrical resistance may significantly increase. If an electric fence has a poor ground on its controller very high electrical short term NEV events may head straight to the low ground resistance milk parlour and cows may be constantly shocked.
Another but not commonly known problem with dairy milking parlour grounding grids is that they often create parallel circuits. These capture electric current between the grid which is carried via the #6 copper bonding wire stipulated in the NEC and connected to the farm's electrical service ground. The earth forms the lower part of the parallel circuit. Cows can die with currents of 10 mA flowing through them but these ground-loop parallel circuits may have as much as +400 mA in them.
When farms and other places are tested for NEV and animal contact voltage its customary to do these tests using the 5 ms/division (DIV) scale of oscilloscopes or to use simple multimeters.
This has lead to confrontation between those testing for NEV and animal contact voltage and farmers. The farmers insisted there was a problem and those testing insisted there wasn't one. Also the majority of site tests often lasted minutes or hours and many NEV events were never seen or recorded.
The inventors of this current invention have tested over 1,500 dairy farms for neutral to earth voltage using the Fluke 105B and also 199C Scopemeter's. The inventors could not understand why despite seeing no NEV events farmers complained their cows still had symptoms associated with it. Since applying this current invention to the same farms other oscilloscopes where used on several electrical problems have been identified and solved which has lead to complete mitigation of NEV problems on farms.
Using the current remote access differential oscilloscope invention, one farmer added over $1.5 million to his cash flow and another added 1.5 gallons of average milk production per day per Jersey breed cow.
New equipment installed on farms may often cause significant NEV and older equipment may suddenly break down causing it too. Unless the farm is constantly monitored and by a high speed oscilloscope system farms may always remain insecure and open to future damage to NEV.
Much of the time spent by experts testing farms for NEV is used in travel and logistics to and from remote farm locations. However in the embodiment of this current invention the farmer simply plugs it in, connects the probes to the testing areas and switches it on and from there on his farm is being constantly monitored by an expert far away.
The current invention is seen to offer a radical solution for farmers with animals being affected by NEV and guarantee future problems never occurring.
An object of the present invention is therefore to neutralize stray current that can flow through the body of an animal(s) bred or kept in a farm building.
An object of the present invention is therefore to test NEV short and long term events 24 hours a day every day of the year and to enable an expert to have complete remote access in both real and past time of all NEV events. That the oscilloscope used for testing will show short time events on the 5 ms/DIV scale of 10 MS/s and the expert may remotely alter scales to verify remedial actions to eliminate NEV has worked successfully.
More specifically, in accordance with the present invention, there is provided a device for sensing neutral to earth voltage events and displaying NEV events on a display both at this device and on a remote display comprising:
The objects, advantages and other features of the present invention will become more apparent upon reading of the following non restrictive description of preferred embodiments thereof, given by way of example only with reference to the accompanying drawings and charts.
In the appended drawings:
In the different figures of the appended drawings, the corresponding elements are identified by the same reference numerals.
In North America and other parts of the world, the structure of the electric distribution networks such as illustrated in
However power supply imbalances also occur off the system primary neutral. Each farm and secondary service is connected to the system neutral. Each of these services injects their imbalances into the system neutral which in turn then contribute to alternating current being injected into off site farms in the area.
The two neutral return systems; (a) the primary system neutral along the street and (b) a farm's secondary service neutral can ‘never’ balance simply because they are two distinct circuits and are tied together.
Utilities may install a solid state reconnection switch device which opens the connection between the primary and secondary neutrals at the farm's power source which is the pole mounted distribution transformer. This device is called the Dairyland Electrical Industries Variable Threshold Neutral Isolator (DEI VT-NI). He current inventor has successfully installed over 170 of these devices. The inventor recommends his customer's who purchase his SvScope first have their electric utility install this device. The DEI VT-NI always fails closed thereby re-establishing continuity between the system and services neutrals which in the case of a serious electrical fault will save the farm from serious power sudden faults by blowing the main system fuse at the distribution transformer.
In
In
When a farm is successfilly isolated from the system neutral we may see typical neutral to earth oscilloscope readings as in
Despite all these ongoing symptoms the oscilloscope the inventors had used which was the Fluke 105B failed to detect any neutral to earth voltage events. The inventors where convinced they needed a more advanced oscilloscope.
On the market are several PCI and PC board type oscilloscope modules. However the price of these was prohibitive when their speeds exceed 100,000 samples per second. The challenge then became how to find a PC based oscilloscope module which had the required speed and resolution to show NEV events and particularly very high speed short duration NEV events. After many months of testing many oscilloscope modules and spending significant money on this quest one was found.
The Scopemeter the inventors had used is most accurate at displaying short term NEV events on the 100 micro-second per division scale. However on many farms the SvScope advanced differential oscilloscope of this current invention has shown 1,000's of serious events but the Scopemeter even on the most accurate scale failed to see one such event.
Essentially what defines this current invention is the complete combination of everything put together which is a new creation. It's the advanced oscilloscope module which is shown in
An essential feature of this current invention is it's secure software features. These are listed in
The following Windows Xp features are disabled;
The following Windows Xp features are removed:
Triggers which lock up the computer operating the advanced differential oscilloscope:
Passwords:
The entire system of this current invention is housed in a NEMA II case made of 16 gauge stainless steel and is described referring to
On the same panel is a reset button for the power tap TVSS bar which offers some degree of protection to this system from power surges.
The front panel houses the main system on/off switch and computer module reset button plus the flat LCD screen.
A hinged panel covers the front panel with support cord lines one either end. This front panel cover has a lock at its top. Upon unlocking the panel is lowered and it has a fixed mounted keyboard and mouse. The mouse may be un-hitched and used freely. The entire case and system may be wall mounted at a convenient work height.
Although the present invention has been described hereinabove by way of preferred embodiments thereof, these embodiments can be modified at will, within the scope of the appended claims, without departing from the spirit and nature of the present invention.
Figures are attached on appended 8 pages.
