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EMF (Electromagnetic Field) Irritants

Harmonics


Harmonics, or whole-number multiples of the input frequency, are triggered by non-linear (non-smooth) current usage. The most obvious culprits are: Fluorescent Lighting (of any type), Dimmer Switches, SPS (Switching Power Supplies) or SMPS (Switch-Mode Power Supplies), and LED or Low Voltage lighting fed off of 120 VAC (which are fed by SMPS), and they have some peculiar properties:

  1. Since Alternating power occurs as bipolar bursts of power, each burst will produce a ringing of the EMF spectrum (trigger many frequencies simultaneously), whose Frequency extent will vary with the energy content of the burst,
  2. although caused by individual bursts, when the bursts are quick enough in time, the harmonics may appear as a continuous stream, when detected by simple devices such as an AM radio, or even sophisticated ones like a spectrum analyzer,
  3. their aggregate waveforms are able to penetrate insulating barriers more easily.

Details on Fluorescent Lighting, in case you lost your notes . . .

Since an electron in an atom has both mass and motion, it contains two types of energy. By virtue of its motion the electron contains KINETIC ENERGY. Due to its position it also contains POTENTIAL ENERGY. The total energy contained by an electron (kinetic plus potential) is the factor which determines the radius of the electron orbit. In order for an electron to remain in this orbit, it must neither GAIN nor LOSE energy.

One accepted theory proposes the existence of light as tiny packets of energy called PHOTONS. Photons can contain various quantities of energy. The amount depends upon the color of the light involved. Should a photon of sufficient energy collide with an orbital electron, the electron will absorb the photon's energy, as shown below left. The electron, which now has a greater than normal amount of energy, will jump to a new orbit farther from the nucleus. The first new orbit to which the electron can jump has a radius four times as large as the radius of the original orbit. Had the electron received a greater amount of energy, the next possible orbit to which it could jump would have a radius nine times the original. Thus, each orbit may be considered to represent one of a large number of energy levels that the electron may attain. It must be emphasized that the electron cannot jump to just any orbit. The electron will remain in its lowest orbit until a sufficient amount of energy is available, at which time the electron will accept the energy and jump to one of a series of permissible orbits. An electron cannot exist in the space between energy levels. This indicates that the electron will not accept a photon of energy unless it contains enough energy to elevate itself to one of the higher energy levels. Heat energy and collisions with other particles can also cause the electron to jump orbits.

Once the electron has been elevated to an energy level higher than the lowest possible energy level, the atom is said to be in an excited state. The electron will not remain in this excited condition for more than a fraction of a second before it will radiate the excess energy and return to a lower energy orbit, as shown above right. To illustrate this principle, assume that a normal electron has just received a photon of energy sufficient to raise it from the first to the third energy level. In a short period of time the electron may jump back to the first level emitting a new photon identical to the one it received.

A second alternative would be for the electron to return to the lower level in two jumps; from the third to the second, and then from the second to the first. In this case the electron would emit two photons, one for each jump. Each of these photons would have less energy than the original photon which excited the electron.

This principle is used in the fluorescent light where ultraviolet light photons (from the excitation and de-excitation of the mercury or neon vapor atoms), which are not visible to the human eye, bombard a phosphor coating on the inside of the glass tube. The phosphor electrons undergo a similar process, and in returning to their normal orbits emit photons of light that are visible, which in essence equates to a shift of emitted frequencies. By using the proper chemicals for the phosphor coating, any color of light may be obtained, including white.

The net result, from a bird's eye view, is a light source that is energy efficient, because once the threshold is crossed for the current to flow due to arcing, it is limited by external electrical / electronic components. But:

  1. Since the gas emissions do not fully quench before the next burst of power, the emissions appear continuous, unless the tube is reaching end-of-life.
  2. Since the excitation and de-excitation are statistical occurrence, there is in addition to luminous emissions, emissions lower in frequency, in the Radio Frequency region.
  3. Since the required current does not resemble the applied voltage, a stream of harmonics ensues with each burst of current used.

For those who haven't caught on yet, the process described above is ionization and de-ionization in a Plasma (electrically conductive gas), occurring with only about 80 Volts or so. Certain physicists would have you believe ionization requires zillions of volts . . . power systems' Alternating Fields introduce currents within our bodies, not unlike those within the plasma just described. But no, no, no, we're not really being "ionized," so please don't use the term unless we're talking high-energy particle physics!

The ease of barrier penetration is employed in TENS (Transcutaneous Electrical Nerve Stimulators) units that are used to alleviate pain. This is an example of a controlled and beneficial biological electrical application. Similar rapid transitions are employed in TASER guns, used by law enforcement to inflict pain and immobilize. The main difference between the two is the magnitude of the voltage transitions. Many harmonics produced by common residential electrical devices ride on the 60 Hz voltage and can likewise penetrate the skin and interfere with the CNS (central nervous system). The CNS performs muscle control by electrical pulses (Action Potential) that are characteristic to the electrochemical messages constantly occurring within the body. When an electrical pulse (or pulses) of similar waveform or repetition (read Frequency) is (are) able to enter the highly conductive structure below the skin, interference in the form of irritation, pain, or outright failure to control physical activity may occur. Other pulses wholly within the brain can similarly be interfered with. When these harmonic emissions have a convenient carrier, such as a whole-house Alternating Electric or Magnetic Field, then these emissions become immediate and whole-body exposure concerns (a former client wished to use a digital widescreen television, but due to the Switching power supply' rapid transitions, and the home's Electric fields from structural cavity wiring (Romex) acting as carriers, she could not tolerate it (it was almost as if the emissions were occurring within her anywhere inside the home)). These are examples of uncontrolled and detrimental biological electrical interference.

Non-Linear consumption - Compact Fluorescent lamp

Note that the two waveforms in the graph are synchronized in time, and their vertical scales are different. The dark blue waveform is the Voltage supplied, the light blue waveform is the Current allowed to flow by the device. The current waveform will be rich in Harmonics of 60 Hz. The harmonic content can be as much as 50%, designated as THD (Total Harmonic Distortion). As long as wiring is proper and there are no uncontrolled currents and associated magnetic fields, their availability in frees-space should be minimal.

Then taking a spectrum analysis of a PC (Personal Computer) power supply, whose current waveform is very similar to that of a compact fluorescent bulb, and to the current waveform shown to the right, we get a display similar to that below.

Non-Linear consumption - PC Power Supply

Note that the spectrum is purposely only displayed to 2 KHz (2000 Hz), to prevent approaching the limitations of the sensing equipment. Yet there are many more harmonics in the higher frequencies, which can be inexpensively detected with an AM radio, whose reception range (540 Khz to 1600 Khz (0.54 to 1.6 Mhz)) will be blanketed anywhere near the power supply, indicating that the frequencies produced saturate the region from 60 Hz up to and beyond 1 Mhz (1,000,000 Hz). Note also that although the PC power supply is a SMPS operating at higher switching frequency than 60 Hz, it appears as if the switching is produced at 60 Hz, because its initial power source is 60 Hz.

Details of SMPS (Switch-Mode Power Supplies)

A Transformer is composed of two or more wire windings. In general one is called the Primary, and all the others are called the Secondaries. When a voltage is applied to the Primary wires, a current will flow that will produce a Magnetic field that envelops the Secondaries. When the Primary voltage and current are Alternating, or continuously changing with time, the Secondaries will produce Alternating voltages, that when connected to a suitable load will produce desired currents. Great effort is made to ensure that there is the greatest amount of coupling between the windings to maximize efficiency. Some of these can be small, as the ones powering small appliances ( the transformer used to power a CFL is about the size of a chick pea), while some can be as large as a house and require forced cooling (those needed to power a town). Their emissions consist of a Magnetic field at the exact frequency of excitation. The span of this magnetic field will be short, for small or large units, due to the great effort expended to maximize coupling between windings.

However, the transformer in these smaller units is rapidly being miniaturized in many applications by Switch-Mode Power Supplies.

Switch-Mode Power Supplies (SMPS), or Switching Regulators make use of the concept that if one increases the frequency of transformer excitation, then the size of the transformer, and its weight, decreases dramatically. A direct application of transformer size reduction is in aircraft, which use 400 Hz, instead of 50 or 60 Hz.

In order to do this, there are necessary electronics to convert the commonly available alternating power to DC, because the electronics require DC to operate and produce the needed oscillations, typically chosen to be above the hearing range ( > about 20 kHz). Conversion from AC to DC is mostly a noise-free process. After the rectifiers are one or more capacitors that serve as energy storage, and filter(s) in an attempt to reduce oscillations from going back into the AC supply. However, given that these storage/filter capacitors charge up ridiculously fast, copious amounts of Harmonics of the supply AC frequency are produced, because the capacitors cause a less than millisecond non-linear inrush of current every 1/2 cycle as they charge. Each time the rectifier circuit charges the storage/filter capacitor, an instantaneous current demand is created that is conveyed back toward the power supplying the SMPS. However, since there is no configuration of passive filtering that will completely eliminate, or sufficiently soften the inrush of current each 1/2 cycle of AC power, a pulse train of transients / spikes will appear on the source supply current. The Harmonics associated with these spikes span the entire frequency range of 60 Hz to the MHz region, generally detectable for each pulse of input voltage (120 times per second for 60 hz, or 100 times per second for 50 Hz), and usually only the odd harmonics will be present, as noted in the spectrum sketch above.

These Harmonic Emissions can usually and easily be detected with an AM radio. A dimmer in use will produce this type of electrical emission 120 times per second (100 times per second outside the USA) and may appear continuous, in time, and frequency, throughout the AM spectrum, blanketing all frequencies in an otherwise quiet background.

Although Harmonics are mostly associated with current (consisting of as much as 50%), due to Ohm's Law a voltage signature of these harmonics is produced at the electric panels and propagated out on all other circuits on the same bus. Nonetheless, the harmonic voltage signature is typically no more than about 3%. Depending on the presence and strength of any locally produced magnetic field, and the presence and strength of the harmonic voltage signature, the AM radio may be reacting to the magnetic or electric field harmonics signature. Depending on the type of wiring used, and a few key measurements, it will be obvious which is which.

Unfortunately, harmonics may also be provided with the supply voltage from the utility. While an IEEE suggested limit is 3% for any one harmonic, and 5% for an aggregate sum, designated as THD (Total Harmonic Distortion (from the ideal / smooth sine wave)), the level may be significantly higher. The same IEEE standard (519) recognizes: "the responsibility that users have not to degrade the voltage of the utility serving other users by requiring nonlinear currents from the utility. It also recognizes the responsibility of the utilities to provide users with close to a sine wave of voltage." My measurement of THD in the incoming voltage with a Picoscope was over 5% at client's residence, yet the utility engineer, supported by a 10,000$+ Dranetz could not determine any to be over 3%. Data falsification due to vested interest? Operator error?

While harmonic emissions are easily controllable at the source, or by appropriate filtering, some unscrupulous marketers are selling "filters" of various sizes with the claim to "clean" "dirty" electricity. While clean electricity is continuously varying with time, and in and of itself is an irritant, harmonic energy riding on the AC can be especially irritating. However, indiscriminately installing filters without investigating the residence's electrical system, and verifying there are no wiring errors, will cause more harm than good. Read more at Capacitive Filter recommendations.

Irritating harmonic or Transient Phenomena can manifest themselves through the Auditory, Visual, Tactile senses, or directly by EMF interaction with the CNS.

When one considers the benefit of shielding from artificial sources, one needs to consider the detriment of also shielding from the Natural Electrical Background.

Some Indoor Solutions, in order of increasing cost:
1) replace any compact fluorescent lamps with incandescent ones,
2) limit the use of conventional fluorescent lamps, or replace with incandescent ones,
3) limit dimmer switch usage,
4) replace dimmer switches with conventional ones,
5) limit usage of line-powered digital devices (SMPS),
6) use 120 V Quartz Halogen lamps, commonly available in various wattage sizes

Some Outdoor Solutions:
1) identify sources and have electric utility repair same.