Melk productie en vuile stroom
zondag, 03 november 2013 - Categorie: Onderzoeken
Bron: Science of the Total Environment 447 (2013) 500-514
Relationship of electric power quality to milk production of dairy herds — Field study with literature review
As little as 10 millivolts (peak to peak) of harmonically distorted voltage (electrical pollution or dirty electricity) in the ground will affect behavior, health and milk production in dairy cows. I routinely measure between 3 and 10 volts in the ground in the US, since the grounded Wye electrical distribution system dumps about 70% of neutral return currents into the earth. Best Sam Milham
Donald Hillman a,⁎, Dave Stetzer b, Martin Graham c, Charles L. Goeke d, Kurt E. Mathson e, Harold H. VanHorn f, Charles J. Wilcox g
a Department of Animal Science, Michigan State University, East Lansing, MI 48824, United States
b Stetzer Electric, Inc., Blair, WI 54616, United States
c Department of Computer Science and Electrical Engineering, University of California, Berkeley, CA 94720-1770, United States
d Goeke Enterprises, Mason, MI 48854, United States
e EIT Rockwell Automation, Mequon, WI, United States
f Department of Animal Science, University of Florida, Gainesville, FL, United States
g Department of Animal Science, Geneticist, University of Florida, Gainesville, FL, United States
H I G H L I G H T S
► Dairy cows were sensitive to earth currents from neutral-to-ground circuit outlets.
► Clamp-on ammeters on grounded-Y down grounds give quick current readings.
► Harmonic distorted voltage affects cows' behavior, health, and milk production.
► Peak-to-peak current must be measured for full impact of current on production.
► IEEE standards should include harmonic current effects on human and animal health.
a r t i c l e i n f o a b s t r a c t
EMF voltage p-p
Public Utility Commissions (PUC) in several states adopted 0.5 volt rms (root mean squared) or 1.0 milliampere as the actionable limit for utilities to respond to complaints of uncontrolled voltage. This study clearly shows that the actionable level should be reduced to 10 mV p-p (peak-to-peak), which is 140 times less than the current standard. Dairy farmer complaints that animal behavior and milk production were affected by electrical shocks below adopted standards were investigated on 12 farms in Wisconsin, Michigan, and Minnesota.
Milk production per cow was determined from daily tank-weight pickup and number of cows milked. Number of transient events, transients, voltage p-p, waveform phase angle degree, sags, and sag-Vrms were measured from event recorders plugged into milk house wall outlets. Data from 1705 cows and 939 data points were analyzed by multiherd least-squares multiple regression and SAS-ANOVA statistical programs.
In five herds for 517 days, milk/cow/day decreased−0.0281 kg/transient event as transient events increased from 0 to 122/day (Pb0.02). Negative effects on milk/cow/day from event recorder measurements were significant for eight independent electrical variables. Step-potential voltage and frequency of earth currents were measured by oscilloscope from metal plates grouted into the floor of milking stalls. Milk decreased as number of 3rd, 5th, 7th, 21st, 28th, and 42nd harmonics and the sum of triplen harmonics (3rd, 9th, 15th, 21st, 27th, 33rd, and 39th) increased/day (Pb0.003). Event recorder transient events were positively correlated with oscilloscope average V p-p event readings. Steps/min counted from videotapes of a dancing cow with no contact to metal in the barnyard were correlated with non-sinusoidal 8.1 to 14.6 mV p-p impulses recorded by oscilloscope for 5 min from EKG patches on legs. PUC standards and use of 500-Ohm resistors in test circuits underestimate effects of non-sinusoidal, higher frequency voltage/current common on rural power lines.
© 2013 Elsevier B.V. All rights reserved.
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