Types of static electricity. occurrence and removal of static

The appearance and danger of static electricity

The cause of electrification can also be induction.
An electric charge with an opposite value appears on the metal surface, the density of which is uniform in all places. The conditions for this phenomenon to occur can be very different. Often the cause is the pumped liquid moving through pipelines or in the form of a falling jet. The same effect is achieved by compressed or liquefied gases, the operation of belt drives, grinding and processing of organic and polymeric materials. Electrification of dielectric materials often reaches a potential difference with high voltage. For example, during the process of pumping gasoline using a pipeline with an isolated section, electrical potentials can fluctuate between 1460 and 14600 volts.

The accumulation of static electricity is a serious danger. In such cases, a strong spark discharge often appears. The released spark energy with a value of 0.01 J is already capable of causing a fire and explosion. A voltage of 300 volts results in an air spark discharge. Taking timely special measures helps prevent the consequences of electrical discharges.

Causes of static electricity

Static occurs under the following conditions:

• contact or separation of two different materials from each other;
• sudden changes in temperature;
• radiation, UV radiation, x-rays;
• operation of paper cutting machines and cutting machines.

Static often occurs during or before a thunderstorm. Thunderclouds, when moving through moisture-saturated air, generate static electricity. The discharge occurs between the cloud and the ground, between individual clouds. The device of lightning rods helps to conduct the charge into the ground. Thunderclouds create an electrical potential on metal objects that cause mild shocks when touched. The impact is not dangerous for humans, but a powerful spark can cause some objects to ignite.

Each resident has repeatedly heard the crash that is heard when removing clothes, the impact of touching the car. This is a consequence of the appearance of statics. An electric discharge can be felt when cutting paper, combing hair, or pouring gasoline. Free charges accompany a person everywhere. The use of various electrical devices increases their occurrence. They occur when pouring and crushing solid products, pumping or pouring flammable liquids, when transporting them in tanks, when winding up paper, fabrics and films.

Harm and benefits of static electricity

Many scientists and inventors tried to use static charge. Cumbersome units were created, the benefits of which were low. The discovery of corona discharge by scientists turned out to be useful. It is widely used in industry. Using an electrostatic charge, complex surfaces are painted and gases are purified from impurities. This is all good, but there are also numerous problems. Electric shocks can be very powerful. They can sometimes infect humans. This happens both at home and in the workplace.

The harm of static electricity manifests itself in shocks of varying power when removing a synthetic sweater, getting out of a car, turning on and off a food processor and vacuum cleaner, laptop and microwave oven. These blows can be harmful.

Static electricity occurs, which affects the functioning of the cardiovascular and nervous systems. You should protect yourself from it. The person himself is also often a carrier of charges. When contacting the surfaces of electrical appliances, they become electrified. If this is a control and measuring device, the matter may end in its failure.

The discharge current brought by a person, with its heat, destroys connections, breaks the tracks of microcircuits, and destroys the film of field-effect transistors. As a result, the circuit becomes unusable. Most often, this does not happen immediately, but at any stage during the operation of the tool.

In factories that process paper, plastics, and textiles, materials often behave incorrectly. They stick to each other, stick to various types of equipment, are repelled, collect a lot of dust on themselves, and are wound incorrectly on reels or bobbins. The reason for this is the occurrence of static electricity. Two charges of equal polarity repel each other. Others, one of which is positively charged and the other negatively charged, attract each other. Charged materials behave the same way.

In printing plants and other places where flammable solvents are used, a fire may occur. This occurs when the operator is wearing non-conductive shoes and the equipment is not properly grounded. The ability to ignite depends on the following factors:

• discharge type;
• discharge power;
• static discharge source;
• energy;
• the presence of solvents or other flammable liquids nearby.

Discharges can be spark, hand, or sliding hand. A spark discharge comes from a person. Carpal occurs on pointed parts of equipment. Its energy is so low that it poses virtually no fire hazard. Sliding brush discharge occurs on synthetic sheets, as well as on rolled materials with different charges on each side of the sheet. It poses the same danger as a spark discharge.

Lethality is a major issue for safety experts. If a person holds on to the bobbin and is in the tension zone, his body will also be charged. To remove the charge, be sure to touch ground or grounded equipment. Only then will the charge go into the ground. But the person will receive a strong or weak electric shock. The result is reflexive movements that sometimes lead to injury.

A long stay in a charged zone leads to a person’s irritability, decreased appetite, and poor sleep.

Dust is removed from the production area using ventilation. It accumulates in pipes and can ignite from a static spark discharge.

Workplace protection

The human body itself is a conductor of current. Therefore, protection against static is required for enterprise employees; every workplace must be protected. The equipment must be grounded and a conductive mat must be placed on the floor. Also, every workplace must have an ionized air emitter that neutralizes the charge. There are different types of protective equipment - these are antistatic strips, ionizing gun, etc. The desired option should be selected based on the characteristics of production.

The person must wear protective clothing. It is imperative to provide operators with special shoes with conductive soles so that the charge seems to flow and be discharged into the ground.

Unpleasant static electricity and protection against it

Let's talk about how to protect yourself at work, at home or while traveling by car.

What you need to know:

1. First of all, we should talk about air humidification. There is a condition: you cannot install humidifiers in close proximity to electrical appliances, because in this case the humidifiers turn into causes of short circuits, which is even more dangerous.
2. When refueling a car, protection is to ensure that no one leaves the car and no one gets into the car. This caution is explained by the fact that movements of this kind cause tension. If the current comes into contact with a flammable liquid, it will cause a strong explosion;
3. In everyday life, you can also use antistatic agents to combat electrical charges from rugs, carpets and vacuum cleaners.

Now there are means aimed at removing static from plastic, from car seat upholstery, from electrical appliances that are capable of delivering a high-voltage static current.

Determination of static electricity

According to the definition, static electricity as an effect is a dangerous phenomenon that threatens the health and practical activities of any person. To comprehend and understand its nature, we should remember that all known substances consist of molecules, and the latter are made of tiny particles called atoms. At their center is a nucleus with protons and neutrons, and groups of electrons rotate around it in different orbits. The total charge of these particles corresponds to the same indicator for protons, so the atom as a whole is neutral.

In some substances, negatively charged electrons are so far from the center that at the slightest disturbance in the energy balance they are displaced from their constant orbits. This usually occurs as a result of friction when a small amount of thermal energy is released in a substance.

How to get

It’s easy to get static electricity at home:

1. It is necessary to put on dry, clean wool socks (it is advisable to preheat them on a radiator) and walk on a nylon carpet without lifting your feet. You shouldn’t shuffle too much, as the discharge will happen faster than necessary. To receive a charge, you must touch a metal object or person;

The easiest way is to shuffle your feet in socks on the carpet.
Important! When checking, you should not touch the electronics, as the charge can damage the chips - statistically, this is the cause of almost 40% of breakdowns.

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1. You need to take a balloon (not made of foil) and inflate it. Then take a woolen object and rub the ball for 10 seconds. You can also place the ball on your head and rub it on your hair. To check, you need to bring the ball to an empty aluminum can lying on its side: if it starts to roll away, the charge has accumulated. To discharge, you need to rub the ball on the metal for a few seconds;
2. To demonstrate and check the charge more clearly, you can make a special electroscope. You will need to take a glass made of foam polystyrene, make 2 holes in the bottom and thread a tube through them so that both ends are outside. You need to attach 4 small clay balls to the top edge with tape at an equal distance from each other, turn the glass over and place it upside down in the center of an aluminum baking sheet. Next, you need to take a piece of aluminum and roll a ball out of it, cut the thread (its length should be 2-3 times greater than the height from the edge of the straw to the baking sheet) and tie the ball to it. The second end must be tied to both ends of the tube, and the latter must be adjusted so that the aluminum ball hangs almost to the baking sheet, but does not touch it. If you bring a charged ball to the ball, the ball will be drawn towards it.

Another way is to rub the inflated balloon on your hair.

How to remove static electricity from a person and surrounding objects

Since the harmfulness of static electricity for adults and children has been proven by time, scientists have long been looking for ways to protect them from this dangerous phenomenon.

Of particular importance is the issue of protecting young children from static, who are more sensitive to its manifestations. For all categories of users, several different approaches have been developed to remove the charge of static electricity that accumulates over time on the surfaces of any object.

The easiest way to get rid of static accumulated on home equipment (on a personal computer or washing machine, for example) is to ground them by connecting the case to a special ground bus.

To prevent a dangerous charge from accumulating on the car body, a special strip of conductive rubber (strap) is attached to its rear bumper. In addition, during long trips in personal vehicles, it is necessary to study the issue of the inadmissibility of accumulation of charges due to changes in body position relative to the seat. As a result of the resulting friction on the covers, sometimes a sufficient amount of them accumulates, which often leads to a noticeable and unpleasant electrical discharge. Therefore, you should periodically moisten the seats by spraying them with a special compact spray bottle.

Electrostatic protection

Rules for protection against static are specified in some regulatory documents. This is mainly GOST 12.4.124, which is entirely devoted to labor safety standards, including appropriate protective measures. There are also “Static Protection Rules” developed for chemical and oil refining industries.

Protection against statics involves solving the following problems:

• Preventing the accumulation of static on equipment components that conduct current - this is achieved by grounding the corresponding devices (not only the equipment and machines themselves, but also communications - for example, pipelines).
• Reducing the electrical resistance of materials to be processed.
• Reducing the intensity of static charge. To do this, it is necessary to select a speed of movement of substances that prevents their splashing and crushing, as well as spraying.
• Purification of liquids and gases from impurities - this is also done to reduce the intensity of the charge.
• Discharge of static charge that accumulates onto people.

The enterprise must have special grounded zones and work areas. It is imperative to take care of grounding door handles and stair handrails, and handles of various equipment. All operators working with such equipment must be equipped with protective clothing.

Causes and sources of occurrence

Today we are confident that static electricity occurs due to several reasons, namely:

1. Due to the presence of any contact between the surfaces of 2 materials with their subsequent separation from each other (for example, the friction of a rubber ball on a woolen sweater or in production when winding materials).
2. Presence of ultraviolet radiation, radiation, etc.
3. With rapid temperature changes.

Most often, static electricity occurs due to the first reason. This procedure is not completely clear, but it is the most accurate explanation of all.

It’s no secret that this phenomenon occurs more often both at work and in everyday life, and to control it, the problem area must be accurately identified and measures taken to protect it. Interesting fact: this phenomenon can cause a "spark" around an object that has the ability to accumulate a charge of electricity. And you ask, what is the danger of this? The point is that when a large charge accumulates, there is a possibility of injury to working personnel in production. To date, only 2 main causes of static electricity shock are known.

The first reason is induced charge. Provided that a person is in an electric field and if he holds a charged object with his hands, then the body of this person can be charged.

If this person is wearing protective boots with insulating soles, then the charge of electricity will remain in him. Could the charge be lost? Of course, the reason for this will be the moment when he touches a grounded object. It is at this moment that the worker will receive an electric shock (at the moment the charge leaks to the ground). The described method of receiving an electric shock occurs when he has shoes on his feet that insulate electricity. After all, when you touch a charged object, because of shoes, the charge remains in the person’s body, and when he touches an object designed to protect against it (grounded equipment), the charge quickly passes through the person’s body and “delivers a shock” with an electric shock. The occurrence of this process is possible both in everyday life and at work; we can say that no one is protected from it. When exposed to synthetic carpets and shoes while a person moves, a charge of static electricity appears. Measures to combat this dangerous phenomenon in everyday life are demonstrated in the video:

https://youtube.com/watch?v=44B3cjlDHeY

Have you ever been electrocuted when getting out of a car? You still don’t know what to do in this case? This occurs when your hand touches a metal door due to the fact that when you exit the car, a “provocation” of a charge occurs between your clothes and the seat. Unfortunately, as mentioned earlier, the only option to get rid of this dilemma is to touch the car door so that through it the current through the car “goes down” to the ground. There is no other easier way to remove static electricity from yourself.

The second cause of static electricity in the workplace is the appearance of a charge on the equipment. This type of electric shock occurs quite rarely, unlike the example above.

So, for your protection and so that you know how to get rid of this trouble, we will consider this entire process. Let’s imagine that a certain object has an impressive charge of static electricity; it happens that your fingers have accumulated such a charge that a “breakdown” occurs and, as a result, a discharge. So here's a little tip: for your protection, you should wear rubber gloves while working (just in case). We reviewed all electrical protective equipment in electrical installations up to 1000 Volts in the corresponding article!

Causes and manifestations

Static voltage occurs due to a violation of the overall balance of electrically charged particles present in any matter. It is formed not only according to a pre-planned scenario: at the request of the teacher or experimenter. In practice, it most often manifests itself without participation and against his will.

A simple example: putting on clothes made from synthetic fabrics. Due to friction with the body and the subsequent appearance of static charges, the material begins to fit tightly and does not allow the outfit to give the desired look. The only possible way out in this situation is to spray it with a special agent called an “antistatic agent.” This is the only way to remove excess charge from synthetic material.

Other typical causes of static charge formation are:

• noticeable temperature changes, which also occur very sharply;
• high level of radiation, leading to an increase in electron energy and the appearance of heterogeneously charged particles in the material;
• the presence of strong induction and magnetic fields.

The first two reasons why a person begins to receive an electric shock do not require any special explanation. In contrast, magnetic induction appears to be a serious problem, especially in recent times.

With the constant increase in the number of household appliances, many of which have inductive elements, the influence of electromagnetic fields on humans is increasing sharply. One of these manifestations is the electrification of the atmosphere due to the separation of air particles into charged electrons and ions, which is essentially the same manifestation of static electricity.

The gradual accumulation of risk factors associated with a variety of sources of extraneous fields has led to a separate direction in science that studies the degree of their danger. On the other hand, scientists have long thought about the beneficial properties of electrification and the possibility of using this effect to serve humans.

The occurrence of static electricity

When the physical body is in a normal neutral state, the balance of negatively and positively charged particles in it is maintained. If it is violated, an electric charge with one sign or another is formed in the body, polarization occurs - the charges begin to move.

For example:

• positive: air, skin, asbestos, glass, leather, mica, wool, fur, lead;
• negative: ebonite, Teflon, selenium, polyethylene, polyester, brass, copper, nickel, latex, amber;
• neutral: paper, cotton, wood, steel.

Static electrification of objects can occur due to various reasons. The main ones are the following:

• direct contact between bodies with subsequent separation: friction (between dielectrics or dielectric and metal), winding, unwinding, moving layers of material relative to each other and other similar manipulations;
• instantaneous change in ambient temperature: sudden cooling, placing in an oven, etc.;
• radiation exposure, ultraviolet or x-ray irradiation, induction of strong electric fields;
• cutting processes - on machines for cutting or cutting paper sheets;
• special directional guidance with a statistical discharge.

At the molecular level, the occurrence of static electricity occurs as a result of complex processes when electrons and ions from colliding inhomogeneous surfaces with different atomic bonds of surface attraction begin to be redistributed. The faster materials or liquids move relative to each other, the lower their resistivity, the larger the areas that come into contact and the interaction forces, the higher the degree of electrification and electrical potential will be.

The sources of electrostatics, both in domestic and industrial conditions, are computer and office equipment, televisions and other units and devices powered by electric current. For example, the simplest computer has a pair of fans to cool the system unit. When the air accelerates, the dust particles contained in it become electrified and, retaining a charge, settle on surrounding objects, people’s skin and hair, and even penetrate into the lungs.

Fans in computer system units are constant sources of static electricity in everyday life

Also, static accumulates in large quantities on monitor screens. In homes and industrial premises, electrostatic charges are formed on floors covered with linoleum or PVC tiles, on people (in hair and on synthetic clothing).

In nature, static electricity is very powerful, arising when cloud masses move: huge potentials of electricity arise between them, which manifests itself in lightning discharges.

In industry, the formation of static charges is often encountered in the following cases:

• friction of conveyor belts on shafts, friction of wire belts on pulleys (especially in cases of slipping and jamming);
• when flammable liquids pass through pipelines;
• filling tanks with gasoline and other liquid petroleum fractions;
• entry and movement of dust particles in air ducts at high speed;
• during grinding, mixing and sifting dry substances;
• during mutual compression of dielectric materials of various types and consistencies;
• mechanical processing of plastics;
• the passage of liquefied gas (especially those containing suspensions or dust) through pipelines;
• moving carts with rubberized tires on insulating flooring.

Security measures

At home, you can protect yourself from static by using the following measures:

1. Humidify the air and ventilate the rooms every day;
2. Regularly carry out wet cleaning to reduce the amount of dust and use special antistatic brushes;

Using a brush helps relieve accumulated tension.

1. If possible, use furniture made from materials that remove static: special linoleum, wood;
2. Do not pet animals in too dry air or comb them with wooden or metal brushes - the plastic is highly electrified;
3. Use antistatic sprays for clothing, remove woolen items slowly to reduce friction;
4. An anti-static strip should be placed on the underside of the vehicle to reduce the formation of static.

In production, electrostatic voltage can be reduced by reducing operating speed, using special materials and grounding. Also, according to GOST, the energy of charge accumulation on the surface of objects should not exceed 40% of the lowest ignition energy.

Precautionary measures must be taken in production

Static electricity is considered by many to be harmless, although not particularly pleasant. However, everything depends on the strength of the charge: in industry or when transporting large quantities of flammable liquids, the accumulated discharge can be very strong and lead to a fire.

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Harm of static electricity to the human body

We cannot remain silent about the fact that electricity is useful for human life; sometimes it allows you to save a person’s life, for example, using current in case of cardiac arrest. But, as a rule, static electricity leads to disruptions in the functioning of the body. Since household static electricity has a small charge, it is not capable of causing serious problems, such as a charge of electricity from a wire, but still such a phenomenon can cause trouble, especially with prolonged exposure.

Namely:

• Sleep is disturbed;
• Disturbances in the vascular system appear due to changes in vascular tone;
• Increased fatigue even with usual loads;
• Problems with the nervous system;
• A minor disruption of muscle function, for example, it could be a muscle tic.

All these are minor violations, but even if they continue for a long period of time, they bring trouble to a person. With poor sleep, a person begins to have problems on the psychological side; constant fatigue and lack of sleep can lead to the development of depression and psychosis. A muscle nervous tic can disrupt the intensity of work, which means that in some cases the employee is forced to consult a specialist and leave the workplace for a while, remaining on sick leave until the condition improves.

For sleeping and bedding, it is best to choose fabrics made from natural materials. Remember, the higher the percentage of synthetic fibers, the higher the likelihood that your body will be affected by static electricity during sleep, provoking certain changes in the human body.

Thus, we can say that prolonged exposure to static voltage leads to unpleasant consequences for a living being. In addition, it should be said that the human body is characterized by the accumulation of electrical charge, because all our internal fluids are first-class electrolytes.

What is the danger of static voltage

The main danger is uncontrolled electric shock. In everyday life, this is practically harmless: for example, when removing a woolen sweater, a person will get an electric shock, but the strength of this charge will be extremely small.

When exposed to an electric field of increased intensity for a long time, a person may experience health problems: headaches, sleep disturbances, irritability, disruption of the cardiovascular and nervous systems.

A strong enough discharge can cause a fire

The danger of static voltage is much higher in production and when transporting flammable substances: with a strong discharge, they can explode or catch fire. For example, dust from dielectric material can accumulate in ventilation and hoods, which easily flares up and flares up due to the constant supply of air. During transportation, electricity can accumulate when pumping or draining liquids, even due to splashing while driving.

Important! At home, it is useful to “ground yourself”, for example, by walking barefoot.

Pros and cons of static manifestation

Dangerous manifestations of electrostatics primarily include the constant friction of poor-quality clothing on the human body and the accumulation of electrical charges on the skin. In the technical field, this effect is especially acute when working as specialist installers in soldering microcircuits. In this case, it threatens the failure of expensive chips or even entire devices assembled on their basis.

When assembling valuable and rare microchips, safety requirements provide for special measures to protect against these unpleasant manifestations.

In technologies associated with the soldering of some microcircuits, electrostatic protection involves wearing a grounded bracelet on the hand, in the presence of which the danger is eliminated by the flow of charges to the ground. Such preventive measures mainly concern outdated K-MOS structures, which are increasingly being replaced by modern microchips that have built-in protection against static electricity.

Danger to humans

Lightning discharges are dangerous manifestations of static electricity

Manifestations of statics as such that are dangerous to humans include:

• thunderstorm discharges accompanied by lightning - they are caused by prolonged friction of air flows; in terms of possible consequences, including fire danger, they far exceed all other manifestations;
• the impact of charges on the biological surface (skin) and the appearance of severe irritation on it;
• dangerous and unpleasant discharges of electricity through the human body when touching metal parts of ungrounded equipment.

The latter phenomenon has nothing to do with critical electric shocks caused by emergency situations when dangerous voltage enters the body of a household appliance.

All these questions relate only to the external side of the manifestations of static electricity, which can be eliminated with the help of technical means of protection. A closer study of this process reveals that the impact of statics on somatics and the human body can lead to more serious consequences:

• systematic sleep disorders;
• changes in the tone of the cardiovascular system;
• severe fatigue;
• the occurrence of problems with the nervous system;
• slight deviations in the functioning of muscle tissue.

Although these disorders are not very noticeable at first, over time changes accumulate in the body that can lead to serious abnormalities. The consequence of poor sleep is mental problems, which in turn leads to other diseases. The harm from this effect in this case is beyond doubt.

The benefits of static electricity

Many scientists and inventors at one time tried to find ways to control static charge for the benefit of humans. They developed bulky and very expensive units, the returns from which, as a rule, remained very low. The only breakthrough in this area is the discovery by scientists of the so-called “corona discharge”.

The unique capabilities of this phenomenon are used not only in production, but also in ordinary everyday conditions. Due to the development of modern techniques for controlling electrostatic phenomena, they are widely used in the following technological processes:

• painting frame bases, as well as surfaces of metal structures and other prefabricated products;
• purification of gases from impurities in the mining industry;
• use in many areas related to materials processing (modern nanotechnology).

Coronary discharge is also widely used in medicine, where it is used to limit the impact of electrostatic discharges on diseased human organs. In addition, based on this effect, many devices have been developed that can ionize the air not only in industrial premises and factory floors, but also in a typical city apartment. One of these useful inventions is an electrostatic filter designed to remove aerosol and mechanical particles from the surrounding air. Thanks to its use, it is possible to get rid of soot, soot and smoke, as well as small dust particles that accumulate in excess in any modern home.

Occupational Safety and Health

Static electricity in the chemical industry primarily represents a fire hazard, since the resulting spark discharges in energy can exceed the minimum ignition energy of flammable media: gases, flammable liquid vapors, dusts of fine materials.

All explosions and fires mainly occur as a result of a spark discharge: a) from the surface of a charged dielectric material, 6) from charged metal ungrounded equipment and c) from the human body to a grounded object.

Thus, to calculate the discharge energy (in mJ) from the surface of a liquid, the following equation can be used:

, (6.2)

where Ca, Sk is the distributed electrical capacitance of the liquid surface in the real apparatus and in the experimental chamber, F/m2; ba is the maximum surface charge density of the liquid in the apparatus, C/m2 (limit bo = 2.65-10 5 C/m2); f is a dimensionless coefficient determined experimentally for each liquid.

However, this formula is valid only under normal conditions. In real conditions, processed liquid products may be at temperatures and pressures that differ from normal ones. Therefore, the formula for calculating Wpasr will look like

, (6.3)

where Upov is the potential of the liquid surface, kV; deltaRa - change in pressure in the apparatus, tank. Pa; deltaT = (Ta - 20) - temperature change, °C; Ta is the temperature in the apparatus.

The energy released during electrostatic discharge is generally defined as

, (6.4)

where b is the surface charge density on the material, C/m2; S—dischargeable surface, m2; U is the potential difference between the discharged surface and the object on which the discharge occurs, V.

For conductive ungrounded objects, as well as the human body, which can be charged both by contact and inductively, having a large capacitance relative to the ground (102...103 pF), when they approach grounded surfaces, a high-power spark discharge occurs in the form of a single spark. The spark discharge energy in these cases is determined by the formula

, (6.5)

The values ​​of the capacitance of a conductive object (Cp.o) and the potential of a conductive object (Un.o) can be measured under production conditions or calculated theoretically.

However, not every spark discharge is capable of igniting a steam, gas or dust-air mixture in devices, tanks or in the air space of a production room. The safety criterion in this case is the following ratio:

, (6.6)

where L, l is the length of the spark gap in real conditions and in the experimental determination of Wmin (minimum) ignition energy of the processed product, m; 0.4 is the safety factor.

The minimum ignition energy for various substances is given in the “Rules”. So, for example, for acetone it is 0.25 mJ, for the Nefras solvent (Galosha gasoline) - 0.234, for ethyl alcohol - 0.14. Moreover, with increasing temperature it decreases sharply.

Along with a fire hazard, static electricity also poses a danger to operating personnel. Light “pricks” when working with highly electrified materials have a harmful effect on the psyche of workers and in certain situations can contribute to injuries on technological equipment. Strong spark discharges, which occur, for example, when packaging granular materials, can also cause pain.

In addition, with the constant passage of small electrification currents through the human body, unfavorable physiological changes in the body are possible, leading to occupational diseases. As a result, in our country, in accordance with GOST 12.1.045-84, permissible levels of electrostatic field strength Epred have been introduced.

Thus, for Epred = 60 kV/m, the maximum stay time without protective equipment is 1 hour. For E = 20 kV/m, the time of stay of personnel in electrostatic fields is not regulated. For E = 20...60 kV/m tadd is determined by the formula

, (6.7)

where Efact is the actual value of E, kV/m.

Static electricity also greatly affects the course of technological processes for obtaining and processing materials and the quality of products. Thus, when flaking fatty acids, the mutual repulsion of charged particles is so significant that some of them settle along the way and do not end up in the hopper. In addition, particles trapped in the hopper stick to its walls, making it difficult to unload the hopper.

When producing polymer films in the presence of charges, their friction against the guides increases, which is explained by the effect of electrostatic adhesion. This leads to uneven deformation of the material and poor winding on the drums.

At high charge densities, electrical breakdown of thin polymer films for electrical and radio engineering purposes may occur, which leads to defective products. Particularly damaging is caused by the adhesion of dust to polymer films caused by electrostatic attraction. As the film passes through the processing equipment, adhered particles are pressed into it, as a result of which the thickness of the film changes, and these particles cannot be detected under production conditions.

Electrification makes it difficult to sift, dry, pneumatically transport and automatically dispense fine materials, since they stick to the walls of the processing equipment and stick together.

To assess the danger of static electricity and the effectiveness of using various means and methods of protection, it becomes necessary to measure the level (current) of electrification, the assessment of which is significantly related to the physical state of the processed materials.

Thus, to assess the electrification of liquids, fine and granular materials transported through pipelines, a method is used to measure the strength of the leakage current from a section of the pipeline isolated from the ground. However, it is much more difficult to make these measurements on dielectrics, since in this case there are no freely moving charges and their distribution on the surface of the material is very heterogeneous.

The contact method is not suitable for this, so the density of charges on the surface of a liquid or solid material is measured mainly by a non-contact method.

For these purposes, single-stage electrometric DC amplifiers with capacitive-type sensors and devices operating on the principle of electrostatic flux are used. Devices of the first type, which are static induction electrometers, have relatively simple circuits and designs and can easily be made portable and self-powered.

In such devices (for example, in the IESP-9 device, developed at M.V. Lomonosov MITHT), the sensitive element of the sensor (Fig. 6.1), connected to the grid of the electrometric lamp L, which is one arm of the bridge circuit, is constantly open and motionless, Therefore, with a constant charge density on an electrifying material, the charge induced on it, which is opposite in sign, is also unchanged.

Rice. 6.1. Schematic diagram of the sensor and measuring bridge of the IESP-9 device (R1, R2, R3, R4 - constant resistance; R5 - variable resistance for setting zero)

In the presence of an induced charge on the disk electrode D, the strength of the anode current of the lamp changes, and the bridge goes out of balance. The bridge imbalance current is increased by a single-stage transistor amplifier and recorded by a pointer instrument. However, these devices cannot operate in a continuous mode, which precludes their use for continuous monitoring of electrification in closed technological equipment.

For these purposes, electrostatic flux meters (dynamic induction electrometers) are used. In these devices, the charge induced on the sensitive element of the sensor (Fig. 6.2), with a constant charge density on the electrifying material, changes periodically. This is achieved by periodic shielding created by a grounded impeller rotating from the engine.

Rice. 6.2. Schematic diagram of an electrostatic flux meter sensor: 1 - sensor body; 2 - sensitive element of the sensor; 3 — trapezoidal holes in the sensor body (6 pcs.); 4—electrified material under study; 5 - impeller; D - engine; E—electric field strength, V/m

To evaluate the electrical parameters of substances and materials (pv and ps), which determine their tendency to electrify, GOST 6433.2 “Solid electrical insulating materials” is used. Methods for determining electrical resistance at constant voltage" (for pv values ​​​​more than 104 Ohm-m), which presents the main dimensions and materials of electrodes, calculation formulas, requirements for sampling, as well as GOST 20214 "Electrically conductive plastics. Determination methods at constant voltage" (for pv values ​​​​less than 104 Ohm), according to which pv is measured by the potentiostric method.

How to remove static electricity

Considering the negative factors of this phenomenon, methods of protection against it excite the minds of many scientists in the world community.

Per person

Before removing static electricity from a person, it is advisable to identify the causes of its occurrence. Eliminating this effect comes down to banal “grounding”. For this it is enough:

• touch the radiator;
• press your palms to the ground for a few seconds;
• pick up a metal object and touch something massive made of conductive material.

It is almost never possible to completely avoid this phenomenon, but you can reduce the likelihood of its occurrence if:

• eliminate friction and contact with moving bodies that are isolated from the ground and have no outlet for discharging the accumulated charge;
• avoid being in an electric field (near operating electrical installations, transformers, power lines);
• switch to clothes and bedding made from natural fabrics;
• when touching synthetic objects, use cotton gloves;
• Avoid shoes with rubber or other electrically insulating soles.

From hair

No less important for people is the question of how to remove static electricity from hair. Electricity is a real disaster for those whose curls are prone to dryness. The following will help you remove the charge and do your hair:

1. A flat comb made of metal, wood or with bristles made of natural materials. Synthetics promote the accumulation of electrical charge.
2. Wash your hair no more than once every two days. Hair that is too clean lacks oil protection and is more susceptible to dryness and, accordingly, electrification.
3. Conditioner and serum with a moisturizing effect. Even a small amount of product will retain moisture in your hair and avoid static electricity.
4. Antistatic cream.

When drying your hair with a hairdryer, do not let it become completely dry.

You need to use varnishes with extreme caution. The polymers they contain can attract electricity

Electricity in the hair can be easily eliminated with a small amount of water or an antistatic wipe.

From clothes

The electrical charge on wardrobe items causes discomfort and attracts dust. You can get rid of static electricity on clothes:

• using metal hangers;
• inserting safety pins into things;
• running a palm dipped in water over the product;
• spraying antistatic agents and special conditioners.

From household items

The electrification of household utensils causes a lot of inconvenience. The main ones are sudden discharges and interior contamination. Before you get rid of static electricity in your apartment, you need to take a closer look at the rules for arranging electrical household appliances and ensuring they are grounded. Clustering electronics in one place creates powerful electric fields.

The main proponent of the accumulation of charges is dry air and dust in the apartment. Constant wet cleaning and forced increase of humidity using wet towels, containers of water or special devices help to overcome this manifestation.

Indoor decorative vegetation helps reduce electrification. In addition to removing the charge, it cleanses the air of toxins and heavy metals.

When cleaning an apartment, special attention should be paid to objects that often move and create a friction effect. To reduce the likelihood of electrical charges accumulating in an apartment, the interior should be composed of items containing less synthetic materials

To reduce the likelihood of electrical charges accumulating in an apartment, the interior should be composed of items containing less synthetic materials.

Practical application of electrostatic phenomena

Figure 2. Application of static electricity. Author24 - online exchange of student work

Electrostatic effects can be used in modern technology, for example, for thoroughly cleaning the air from smoke and dust particles using special electrostatic precipitators, for uniform spraying of paint with spray guns, for printing materials in office Xerox-type machines, and in the production of sandpaper. The shielding phenomenon of conductors in a number of specific cases is used for electrostatic protection from external factors in the form of electric fields of electrical measuring sensitive devices.

Finished works on a similar topic

Course work Application of electrostatics 490 ₽ Abstract Application of electrostatics 220 ₽ Test paper Application of electrostatics 190 ₽

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A metal mesh can reliably protect any flammable building, such as a powder warehouse, from a sudden lightning strike. The characteristics of excess electrical charges are determined on the surface of conductors, and then widely used in the device of the Van der Graaff generator - a device for producing ultra-strong electric and magnetic fields.

Note 1

By repeatedly and uniformly transferring small portions of a positive charge to the medium of a hollow conductor, it is possible to gradually accumulate the necessary charge on its outer surface, the rate of which is directly and fundamentally limited only by the insulation of a given installation.

The initial effect from such a source is transformed by means of brushes into a moving closed ribbon, which must be made of paper or silk, and is removed from the object using the same brush.