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Stray Voltage from VFD VFD controls create harmonics or "stray voltage", which causes Radio Frequency Interference or RFI. A VFD can make neutral-earth voltage worse, by several mechanisms: capacitive coupling of switching frequency, input rectifier harmonics, switching current coupling to rotors, etc. VFD's can cause interference with radios, televisions, cordless phones, and other devices because they are simply in the same area, or they are plugged into the same power company as the VFD. Stray voltage from a VFD goes back into the electric grid and causes problems for the neighbors. Stray voltage is also known as "dirty power" which can cause everything on the entire electric grid to be less efficient. Some utilities in Nebraska and Iowa have started charging an extra tariff on the electric bill for the amount of "stray voltage" being introduced from the user. "Stray Voltage" has been well documented as causing health problems with dairy cattle. Excessive stray voltage at a dairy can cause reductions in milk production, mastitis of the udder, loss of unborn calves, sore feet and other problems. The dose response curve and replication (50 or more cows per herd) makes it obvious. With humans, each one of us is viewed in isolation. There has been extreme reluctance to examine electrical exposure via plumbing, ground currents, dirty power on wires or any other source. People are much more likely to be treated symptom by symptom, illness by illness. While the human health effects of exposure to electrical ground currents have gotten little media attention, that is not because they are non-existent. Electrical ground currents are pretty conclusively linked to an increase in the risk of childhood leukemia. The high frequencies that pollute our electricity and cause the electrical ground currents have been linked to increased blood glucose levels, multiple sclerosis symptoms, asthma, allergies, migraines, chronic fatigue syndrome and an assortment of other symptoms. Line filters, installed prior to the VFD, as well as extra grounding techniques, can reduce the amount of stray voltage emitted from VFD's. More recent VFD's have incorporated line and load filters to reduce the RFI problem. These filters can only reduce, not eliminate the interference. Line and load filters also have heat losses which increases energy consumption. Stray voltages that get past these filters, can increase energy consumption of all other electrical equipment on the grid. "Constant Pressure" has many benefits for your water system. "Constant Pressure" is really the only job that a VFD is trying to accomplish. The Cycle Stop Valve or CSV, was designed to mimic the "constant pressure" delivery of a VFD, without needing the computerized controls that create so many problems. The best technology is not always electronic. The best technology is one that has been reduced to the simplest form that will accomplish the job at hand. The CSV is newer technology and has been used to replace VFD's every day since 1993. The CSV reduces energy consumption of a pump as much as varying the speed with a VFD. The CSV is also completely mechanical and has no electronics to worry about keeping cool and clean. Standard speed pumps with 60 hertz motors and controls that are used with the CSV, do not cause Radio Frequency Interference or "Stray Voltage", that could cause problems for you and your neighbors. |
| Cycle Stop Valves® is a registered trademark. All right reserved unless prior authorization is obtained. Cycle Stop Valves are patented: Patent number 5,988,984 and other patents pending. |
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