The information in this article, alone, should alarm everyone! Now, add the comprehensive published studies on Microwave pulsed Radio waves. This is the smart grid technology, which is also riding on the power lines; exposing us to deadly environmental pollution every second of the day and night! We cannot afford to ignore this issue….Sandaura
Human health //
By increasing population of the world, towns are expanding, many buildings construct near high voltage overhead power transmission lines. The increase of power demand has increased the need for transmitting huge amount of power over long distances. Large transmission lines configurations with high voltage and current levels generate large values of electric and magnetic fields stresses which affect the human being and the nearby objects located at ground surfaces.
This needs to be investigating the effects of electromagnetic fields near the transmission lines on human health.
The electricity system produces extremely low frequency electromagnetic field which comes under Non ionizing radiations which can cause health effects. Apart from human effect, the electrostatic coupling & electromagnetic interference of high voltage transmission lines have impact on plants and telecommunication equipments mainly operating in frequency range below UHF.
Is power line EMF safe?
This is the controversy discussion directly eludes on Government Regulation policy and Power Company. There are lots of supporting documents and research paper in favor and criticize this arguments.
What are the electric and magnetic fields?
- Electric and magnetic fields, often referred to as electromagnetic fields or EMF, occur naturally and as a result of the Power generation, Power Transmission, Power distribution and use of electric power.
- EMF is fields of force and is created by electric voltage and current. They occur around electrical devices or whenever power lines are energized.
- Electric fields are due to voltage so they are present in electrical appliances and cords whenever the electric cord to an appliance is plugged into an outlet (even if the appliance is turned off).
- Electric fields (E) exist whenever a (+) or (-) electrical charge is present. They exert forces on other charges within the field. Any electrical wire that is charged will produce an electric field (i.e. Electric field produces charging of bodies, discharge currents, biological effects and sparks). This field exists even when there is no current flowing. The higher the voltage, the stronger is electric field at any given distance from the wire.
- The strength of the electric field is typically measured in volts per meter (V/m) or in kilovolts per meter (kV/m). Electric fields are weakened by objects like trees, buildings, and vehicles. Burying power lines can eliminate human exposure to electric fields from this source.
- Magnetic fields result from the motion of the electric charge or current, such as when there is current flowing through a power line or when an appliance is plugged in and turned on. Appliances which are plugged in but not turned on do not produce magnetic fields.
- Magnetic field lines run in circles around the conductor (i.e. produces magnetic induction on objects and induced currents inside human and animal (or any other conducting) bodies causing possible health effects and a multitude of interference problems). The higher the current, the greater the strength of the magnetic field.
- Magnetic fields are typically measured in tesla (T) or more commonly, in gauss (G) and milli gauss (mG). One tesla equals 10,000 gauss and one gauss equals 1,000 milli gauss.
- The strength of an EMF decreases significantly with increasing distance from the source.
- The Strength of an electric field is proportional to the voltage of the source. Thus, the electric fields beneath high voltage transmission lines far exceed those below the lower voltage distribution lines. The magnetic field strength, by contrast, is proportional to the current in the lines, so that a low voltage distribution line with a high current load may produce a magnetic field that is as high as those produced by some high voltage transmission lines.
- In fact, electric distribution systems account for a far higher proportion of the population’s exposure to magnetic fields than the larger and more visible high voltage transmission lines.
- Electrical field: the part of the EMF that can easily be shielded.
- Magnetic field: part of the EMF that can penetrate stone, steel and human flesh. In fact, when it comes to magnetic fields, human flesh and bone has the same penetrability as air!
- Both fields are invisible and perfectly silent: People who live in an area with electric power, some level of artificial EMF is surrounding them.
- The magnetic field strength produced from a transmission line is proportional to: load current, phase to phase spacing, and the inverse square of the distance from the line.
- Many previous works studied the effect of different parameters on the produced magnetic field such as: the distance from the line, the conductor height, line shielding and transmission line configuration and compaction.
Electric and Magnetic Field (EMF) Effects
Extremely high voltages in EHV lines cause electrostatic effects, where as short circuit currents & line loading currents are responsible for electromagnetic effects. The effect of these electrostatic fields is seen prominent with living things like humans, plants, animals along with vehicles, fences & buried pipes under & close to these lines.
1. EMF effects on human beings
The human body is a composed of some biological materials like blood, bone, brain, lungs, muscle, skin etc. The permeability of human body is equals to permeability of air but within a human body has different electromagnetic values at a certain frequency for different material.
The human body contains free electric charges (largely in ion-rich fluids such as blood and lymph) that move in response to forces exerted by charges on and currents flowing in nearby power lines. The processes that produce these body currents are called electric and magnetic induction.
In electric induction, charges on a power line attract or repel free charges within the body. Since body fluids are good conductors of electricity, charges in the body move to its surface under the influence of this electric force.
For example, a positively charged overhead transmission line induces negative charges to flow to the surfaces on the upper part of the body. Since the charge on power lines alternates from positive to negative many times each second, the charges induced on the body surface alternate also. Negative charges induced on the upper part of the body one instant flow into the lower part of the body the next instant.
Thus, power-frequency electric fields induce currents in the body (Eddy Current) as well as charges on its surface.
The currents induced in the body by magnetic fields are greatest near the periphery of the body and smallest at the center of the body.
Read full article at: http://electrical-engineering-portal.com/how-hv-transmission-lines-affects-humans-plants