(if there is an additional option)

from 0.1 kV to 18 kV

from 1 kV/m to 180 kV/m

The Yuman company offers a wide range of instruments for measuring static electricity produced by ELTEX (Germany).

The ability to accurately measure electrostatic charges (including high voltages, electric fields, and high resistances associated with charge-carrying materials) provides the information basis for destroying destructive unwanted electrostatic energy. High resistance measurement is also an important tool in safety monitoring applications. Accurate leakage resistance measurement contributes to quality control and assurance, maintaining standardized properties in materials.

Given the instability of electrostatic phenomena, static electricity measurement must also take into account various sources of error. This means that the measuring process itself must meet precise requirements. Eltex measuring equipment is distinguished by its high accuracy and wide range of possible applications.

We offer devices for measuring static electricity ELTEX (Germany):

Electric field meter EMF58

Highly sensitive portable device. The EMF58 can measure charge rise, level and polarity and evaluate the effectiveness of any countermeasures. Available four measurement ranges from ±0 kV/m to ±2 mV/m.

Electric field meter EM02

Handheld device for safe measurement of static charges. Measuring range: ±0 to ±2 mV/m.

Electric field meter EM03

Hand-held, convenient device for measuring static charges, with a measuring distance selectable between 2 and 20 cm. Automatic conversion and display of field strength in volts. Measuring range: ±0 to ±200 kV.

The Yuman company offers a wide range of instruments for measuring static electricity produced by ELTEX (Germany).

The ability to accurately measure electrostatic charges (including high voltages, electric fields, and high resistances associated with charge-carrying materials) provides the information basis for destroying destructive unwanted electrostatic energy. High resistance measurement is also an important tool in safety monitoring applications. Accurate leakage resistance measurement contributes to quality control and assurance, maintaining standardized properties in materials.

Given the instability of electrostatic phenomena, static electricity measurement must also take into account various sources of error. This means that the measuring process itself must meet precise requirements. Eltex measuring equipment is distinguished by its high accuracy and wide range of possible applications.

We offer devices for measuring static electricity ELTEX (Germany):

Electric field meter EMF58

Highly sensitive portable device. The EMF58 can measure charge rise, level and polarity and evaluate the effectiveness of any countermeasures. Available four measurement ranges from ±0 kV/m to ±2 mV/m.

Electric field meter EM02

Handheld device for safe measurement of static charges. Measuring range: ±0 to ±2 mV/m.

Electric field meter EM03

Hand-held, convenient device for measuring static charges, with a measuring distance selectable between 2 and 20 cm. Automatic conversion and display of field strength in volts. Measuring range: ±0 to ±200 kV.

What is static electricity

Static electricity occurs when intraatomic or intramolecular equilibrium is disturbed due to the gain or loss of an electron. Typically, an atom is in equilibrium due to the same number of positive and negative particles - protons and electrons. Electrons can easily move from one atom to another. In doing so, they form positive (where there is no electron) or negative (a single electron or an atom with an extra electron) ions. When this imbalance occurs, static electricity occurs.

The electric charge of an electron is (-) 1.6 x 10 -19 coulombs. A proton with the same charge has positive polarity. The static charge in coulombs is directly proportional to the excess or deficiency of electrons, i.e. number of unstable ions. A coulomb is a basic unit of static charge that determines the amount of electricity passing through the cross-section of a conductor in 1 second at a current of 1 ampere.

A positive ion is missing one electron, hence it can easily accept an electron from a negatively charged particle. A negative ion, in turn, can be either a single electron or an atom/molecule with a large number of electrons. In both cases, there is an electron that can neutralize the positive charge.

The main causes of static electricity:

1. Contact between two materials and their separation from each other (including friction, winding/unwinding, etc.).
2. Rapid temperature change (for example, when the material is placed in the oven).
3. Radiation with high energy values, ultraviolet radiation, X-rays, X-rays, strong electric fields (unusual for industrial production).
4. Cutting operations (for example, on cutting machines or paper cutting machines).
5. Electromagnetic induction (the appearance of an electric field caused by a static charge).

Surface contact and material separation are perhaps the most common causes of static electricity in roll film and sheet plastic processing applications. Static charge is generated during the process of unwinding/winding materials or moving different layers of materials relative to each other. This process is not entirely clear, but the most truthful explanation for the appearance of static electricity in this case can be obtained by drawing an analogy with a flat-plate capacitor, in which mechanical energy is converted into electrical energy when the plates separate:

Resultant stress = initial stress x (final plate spacing/initial plate spacing).

When the synthetic film touches the feed/take-up shaft, the low charge flowing from the material to the shaft causes an imbalance. As the material passes the contact zone with the shaft, the stress increases in the same way as in the case of capacitor plates at the moment of their separation. Practice shows that the amplitude of the resulting voltage is limited due to electrical breakdown that occurs in the gap between adjacent materials, surface conductivity and other factors. When the film exits the contact zone, you can often hear a faint crackling sound or observe sparking. This occurs at the moment when the static charge reaches a value sufficient to breakdown the surrounding air. Before contact with the shaft, the synthetic film is electrically neutral, but during the process of movement and contact with the feed surfaces, a flow of electrons is directed towards the film and charges it with a negative charge. If the shaft is metal and grounded, its positive charge drains quickly.

Most equipment has many shafts, so the amount of charge and its polarity can change frequently. The best way to control static charge is to accurately detect it in the area immediately in front of the problem area. If the charge is neutralized too early, it may recover before the film reaches this problem area.

In theory, the occurrence of a static charge can be illustrated by a simple electrical circuit:

C - acts as a capacitor that stores charge, like a battery. This is usually the surface of a material or product.
R is a resistance that can weaken the charge of a material/mechanism (usually with weak current circulation). If the material is a conductor, the charge flows to the ground and does not cause problems. If the material is an insulator, the charge will not be able to drain, and difficulties arise. A spark discharge occurs when the voltage of the accumulated charge reaches a limiting threshold.

Current load is a charge generated, for example, during the movement of a film along a shaft. The charging current charges the capacitor (object) and increases its voltage U. While the voltage rises, current flows through the resistance R. Balance will be achieved at the moment when the charging current becomes equal to the current circulating through the closed circuit of the resistance. (Ohm's Law: U = I x R).

If an object has the ability to accumulate a significant charge, and if high voltage is present, static electricity will cause serious problems such as sparking, electrostatic repulsion/attraction, or electrical shock to personnel.

Static charge can be either positive or negative. For direct current (AC) and passive (brush) arresters, charge polarity is usually not important.

Static charge measurement

Measuring the magnitude of a static charge is a very important procedure, which allows you to detect the presence of a charge, determine its amplitude and its source.
As noted above, static electricity occurs when there is a deficiency or excess of electrons in an atom. Due to the fact that it is impossible to measure the amount of charge on the surface of an object in coulombs, the resistance or electric field strength associated with the static charge is measured. This measurement method is widely used in industry.
The relationship between field resistance and intensity is that at any point the resistance is a component of the intensity gradient.
Measuring instruments are assembled mainly according to the scheme presented below and measure the voltage on the surface of the object.

A - the voltage of the capacitor changes along with the change in the amount of charge.

By taking measurements from a distance of 100 mm, and using the formula Q (charge) = C (capacitance) x U (voltage), you can calculate the capacitance.

Measuring instruments are usually easy to use and very useful for analyzing problems that have occurred or predicting their occurrence in the future.

When measuring static electricity, it is important to follow the instrument's operating instructions. The electric field acts in a single direction, so its practical study is not difficult. Some of the most interesting and important characteristics of the electric field for measuring charge are:

Electric field is a section of space in which electric forces act, the magnitude of which is expressed in coulombs.
All charged objects are surrounded by an electric field.
Field lines run perpendicular to the surface of the object and indicate the direction in which the force acts.
The electric field can cover several objects, which is important to take into account when taking measurements and implementing measures to neutralize static charge.

As noted above, in airspace the electric field lines run perpendicular to the surface of a charged object. This allows measurements to be made with very high accuracy.

In the case of synthetic film production and processing, there is an important detail to note. As the material moves along the shaft, an electrical charge is transferred to the shaft and the field appears to disappear. Therefore, it is not possible to make accurate measurements near the shaft. The electric field reappears when the material overcomes the contact zone and the static charge can again be accurately measured.

Static Electricity Problems

There are 4 main areas:

Static discharge in electronics

It is necessary to pay attention to this problem, because... it often occurs during handling of electronic units and components used in modern control and measuring devices.
In electronics, the main danger associated with static charge comes from the person carrying the charge and cannot be ignored. The discharge current generates heat, which leads to the destruction of connections, interruption of contacts and rupture of microcircuit tracks. High voltage also destroys the thin oxide film on field-effect transistors and other coated elements.

Often components do not completely fail, which can be considered even more dangerous because... The malfunction does not appear immediately, but at an unpredictable moment during the operation of the device.
As a general rule, when working with static-sensitive parts and devices, measures should always be taken to neutralize the charge accumulated on the human body. Detailed information on this issue is contained in the documents of the European standard CECC 00015.

This is perhaps the most widespread problem encountered in plants involved in the production and processing of plastics, paper, textiles and related industries. It manifests itself in the fact that materials independently change their behavior - they stick together or, conversely, repel each other, stick to equipment, attract dust, wrap incorrectly around the receiving device, etc.

Attraction/repulsion occurs in accordance with Coulomb's law, which is based on the principle of square opposition. In simple form it is expressed as follows:

Force of attraction or repulsion (in Newtons) = Charge (A) x Charge (B) / (Distance between objects - (in meters)).

Consequently, the intensity of this effect is directly related to the amplitude of the static charge and the distance between attracting or repulsive objects. Attraction and repulsion occur in the direction of the electric field lines.
If two charges have the same polarity, they repel, if they have the opposite polarity, they attract. If one of the objects is charged, it will provoke an attraction, creating a mirror copy of the charge on neutral objects.

The risk of fire is not a common problem for all industries. But the likelihood of fire is very high in printing and other enterprises where flammable solvents are used.
In hazardous areas, the most common sources of fire are ungrounded equipment and moving conductors. If the operator is wearing athletic or non-conductive shoes while in a hazardous area, there is a risk that his body will generate a charge that could cause solvents to ignite. Ungrounded conductive machine parts also pose a hazard. Everything located in the hazardous area must be well grounded.

The following information provides a brief explanation of the fire-causing potential of static discharge in flammable environments.

The ability of a discharge to provoke a fire depends on many variable factors:

• discharge type;
• discharge power;
• discharge source;
• discharge energy;
• the presence of a flammable environment (solvents in the gas phase, dust or flammable liquids);
• minimum ignition energy (MEI) of a flammable environment.

There are three main types - spark, brush and sliding brush discharges. Corona discharge in this case is not taken into account, since it has low energy and occurs quite slowly. Corona discharge is most often harmless and should only be considered in areas of very high fire and explosion hazard.

Spark discharge

It generally comes from a moderately conductive, electrically insulated object. It could be a human body, a machine part, or a tool. It is assumed that all the energy of the charge is dissipated at the moment of sparking. If the energy is higher than the MEV of the solvent vapor, ignition may occur.
The spark energy is calculated as follows: E (in Joules) = ½ C U2.

Wrist discharge

Brush discharge occurs when sharp parts of equipment concentrate charge on the surfaces of dielectric materials, the insulating properties of which lead to its accumulation. A brush discharge has lower energy compared to a spark discharge and, accordingly, poses less of a ignition hazard.

A sliding brush discharge occurs on sheet or roll synthetic materials with high resistivity, having an increased charge density and different polarity of charges on each side of the sheet. This phenomenon can be caused by friction or spraying of the powder coating. The effect is comparable to the discharge of a parallel-plate capacitor and can be as dangerous as a spark discharge.

The magnitude and geometry of the charge distribution are important factors. The larger the volume of a body, the more energy it contains. Sharp angles increase field strength and support discharges.

If an object containing energy does not conduct electricity very well, such as the human body, the resistance of the object will weaken the discharge and reduce the danger. For the human body, a rule of thumb is to assume that any solvents with an internal minimum ignition energy of less than 100 mJ can ignite, even though the energy contained in the body may be 2 to 3 times higher.

The minimum ignition energy of solvents and their concentration in the hazardous area are very important factors. If the minimum ignition energy is lower than the discharge energy, there is a risk of fire.

The issue of static shock risk in industrial environments is receiving increasing attention. This is due to a significant increase in occupational hygiene and safety requirements.
Electrocution caused by static electricity is, in principle, not particularly dangerous. It is simply unpleasant and often causes a strong reaction.
There are two common causes of static shock:

If a person is in an electric field and holds onto a charged object, such as a film spool, it is possible that their body will become charged.

The charge remains in the operator's body if he is wearing shoes with insulating soles until he touches grounded equipment. The charge flows to the ground and strikes a person. This also happens when the operator touches charged objects or materials - due to insulating shoes, the charge accumulates in the body. When the operator touches metal parts of the equipment, the charge can leak and cause an electrical shock.

When people walk on synthetic carpeting, a static charge is generated when there is contact between the carpet and the shoes. The electric shocks that drivers receive when leaving their car are provoked by the charge that arises between the seat and their clothing at the time of lifting. The solution to this problem is to touch a metal part of the car, such as a door frame, before rising from the seat. This allows the charge to flow safely to the ground through the vehicle's body and tires.

Such an electric shock is possible, although it occurs much less frequently than damage caused by the material.
If the winding reel has a significant charge, it happens that the operator's fingers concentrate the charge to such an extent that it reaches the point of breakdown and a discharge occurs. In addition, if a metallic, ungrounded object is placed in an electric field, it can become charged by an induced charge. Because a metal object is conductive, the moving charge will discharge into a person who touches the object.

The article was prepared based on materials from Fraser-antistatic (UK)