Gauss Meter / Tesla Meter

Gauss meters are named after the unit Gauss, in which the magnetic flux density can be measured. Gauss meters are therefore the measuring instruments for the quantitative evaluation of magnetic fields. The unit for magnetic flux density corresponding to the international system of units SI is not Gauss, but Tesla. One tesla corresponds to one newton per ampere and meter. Since 10,000 Gauss also correspond to one Tesla, the conversion between Gauss and Tesla is very simple. Many Gauss meters still show both units, so they are both Gauss meters and Tesla meters. The magnetic field strength can be calculated from the magnetic flux density using the magnetic permeability and vice versa. Both values can be used to indicate how strong a magnetic field or its effect is compared to the other magnetic fields. The relationship between magnetic flux density and magnetic field strength can be seen from the following formula:

Gauss meters are often used to clarify that people are not endangered by the electromagnetic radiation. For this purpose, the measurements are carried out in the living, working or other common areas and then the values are compared with the limit values from

- the EU Directive 2013/35/EU,
- the DGUV regulation 15 (BGV B11),
- the 26th Federal Immission Control Ordinance (2nd BImSchV),
- the Occupational Health and Safety Ordinance on Electromagnetic Fields (EMFV 2016) or
- the guidelines of the International Commission on Non-Ionizing Radiation Protection (ICNIRP)
- EN 62233 (VDE 0700-366) "Methods for measuring electromagnetic fields of household and similar electrical appliances with regard to the safety of persons in electromagnetic fields".

Gauss meters are also used for many measurements in connection with the technical use of magnets. Gauss meters allow the exact and repeatable determination of the strength of magnetism of permanent magnets and ferromagnetic components and thus the non-destructive measurements:

- of magnetic components and circuits such as coils, relays, magnetic switches
- at loudspeakers
- on direct current and alternating current motors
- for the classification of magnets
- of residual magnetic fields, stray and leakage fields.

A Gauss meter can be used to determine whether the static or dynamic electromagnetic fields affect the precise electronic devices at the place of installation.

When searching for a Gauss meter for measuring electromagnetic radiation, it should be determined before starting, which electromagnetic fields are to be recorded. There are Gauss meters that only measure static magnetic fields, those that evaluate static and low-frequency magnetic fields, and the devices that use additional sensors to simultaneously measure the values for electric fields and high-frequency electromagnetic fields. For the measurement of magnetic fields, there are Gauss meters that can measure all three directions of the field separately and then display them both separately as x, y and z components and in a vector way added as an effective value.

The next criteria for the selection are measuring range and resolution. In the case of a Gauss meter with several sensors, it is necessary to check for each individual sensor whether the measuring range is suitable for the intended use. For example, the maximum value for the magnetic flux density can be 2 Gauss (0.2 millitesla) or 30,000 Gauss (3 Tesla). A higher maximum value usually means less detailed display steps. Some Gauss meters allow the selection from several measuring ranges or automatically switch to the appropriate measuring range.

Closely related to the measuring range and resolution is the display unit of the measured variables. As a rule, Gauss meters can display the measured value for magnetic flux density in both Gauss and Tesla. This facilitates a comparison with the limit values from various sources. For high-frequency fields, the strength can be given as electric field strength in volts per meter, as magnetic field strength in amperes per meter, or radiant power in watts per square meter. If several of these values are required, it is advantageous if they can be selected using the Gauss meter and do not have to be converted between different units.

Sufficient memory facilities and the possibility of transferring the measured values to a PC make it easier to evaluate the measurements. Gauss meters with data logger function should be used for continuous measurements. Optical or acoustic alarms when the preset limits are reached are helpful if the Gauss meter is to be used for warnings in potentially dangerous areas.

According to the articles 6(§3) and 9(§1) of EEC Directive 89/391, the employer must assess the risks in the workplace for his employees and take protective measures where necessary. The risk assessment must also include the exposure of workers to the electromagnetic fields. For this, these fields must either be calculated or measured. Both Gauss meters and EMF measuring devices are suitable for measuring the magnetic fields. The exposure limit values and triggering thresholds for electromagnetic fields at the workplace are regulated, among others, in the EU Directive 2013/35 and, for Germany, once again specifically in the Occupational Health and Safety Ordinance on Electromagnetic Fields (EMFV 2016) and in DGUV Regulation 15. These limit and threshold values are subdivided according to the effects and frequency ranges.

The effects of electromagnetic fields can be divided into direct and indirect effects.
Indirect effects of electromagnetic fields are for example:

- the influence of implanted medical devices such as pacemakers, defibrillators and insulin pumps.
- contact currents
- triggering of electrical ignition devices
- fires and explosions caused by sparks
- bullet effect of ferromagnetic objects in strong magnetic fields.

The details on the hazards to persons with active or passive implants can be found, among others, in Research Report 451 of the EMF Working Group of the Federal Ministry of Labour and Social Affairs.
Direct effects of high-frequency electromagnetic fields range from heating of body tissue to burns and other tissue damage. Static and low-frequency fields with frequencies up to 100 Hz cause, among others:

- light sensations on the retina,
- metallic taste in the mouth,
- uncontrolled muscle contractions,
- nausea,
- vertigo.

In order to exclude the dangers from such effects, the electromagnetic exposure is measured with the Gauss meter or EMF measuring device and compared with the specified limit values. A distinction is made between exposure limit values and triggering thresholds.
The exposure limit values, which must not be exceeded, were established on the basis of scientifically proven acute effects. The exposure limit values refer to the maximum levels in the body. The limit values for sensory effects are intended to limit the temporary disturbances of sensory perception and minor changes in the brain function. Separately from that, the limit values for health impacts caused by heating or electrical stimulation of nerves and muscle tissue are considered.

Trigger thresholds have been specified so that there was no necessity to carry out the measurements on the body exposed to radiation in order to assess the risk. Instead, the strength of the causative external field is measured and evaluated. For exposure to electric fields, certain protective and preventive measures are required if the low or high trigger threshold is exceeded. In the case of the magnetic fields, the low trigger level applies to sensory effects and the high trigger level – to health effects.

It is not only employees who should be protected against the dangers of electromagnetic radiation. In the Federal Republic of Germany, the Twenty-sixth Ordinance for the Implementation of the Federal Immission Control Act (Ordinance on Electromagnetic Fields - 26th BImSchV) regulates the restrictions on the construction and operation of stationary high-frequency and low-frequency installations and of direct current installations with a nominal voltage of 2 kilovolts or more. This Ordinance serves to protect the public, the neighborhood and the environment from the harmful effects of electric, magnetic and electromagnetic fields. Electromagnetic fields with frequencies from 100,000 Hertz to 300 Gigahertz are referred to as high-frequency. The strength of these fields is determined with a suitable Gauss meter either by the electric field strength or by the magnetic field strength. Since both field strengths influence each other, the other does not have to be measured, but can be determined from the one already measured. The high-frequency electromagnetic fields propagate at the speed of light and decrease their field strength in proportion to the square of the distance. This means that when the distance to the radiation source is increased to three times, the field strength decreases to a ninth of the previous value. If there is a possibility to remove the workplace or location from the radiation source, with the help of the suitable Gauss meter it can be determined without much effort in which areas the recommended threshold values are not reached.

Magnetic fields cannot be seen, but they may affect the electronic devices and cause various malfunctions, the reasons for which seem to be not evident. In addition, they may have a negative impact on the health of people which spend a lot of time within these fields.

The device is easy to operate and if the choice is a triaxial gauss meter (which is more expensive in comparison to single-axis devices), then there is even no need to think about how to hold it, it will detect at once the places where the trouble-making circuits are, as well as give information about the strength of the magnetic field at the place of measurement. The Gauss meter provides the measurement in real time, which means that this is a perfect device for immediate trouble shooting and electromagnetic monitoring, for example, in the building. The way it works may be compared with the metal detector, since it gives a signal and indication of where to search. Sometimes small magnetometer actually is a part of the metal detectors and “participates” in a detection and search of various items. There are mainly two types of Gauss meter that are especially popular among the users: those that show the strength (scalar) and those that indicate direction of the EMF (vector) (sometimes one device comprises both of these functions).

Gauss meter is an indispensable device for those who work as professional electricians, though, it may also be helpful in determining the intensity of electromagnetic radiation from the devices, like, for example, household devices. Its small size provides for the convenience of operation and it can be easily carried around.

There is wide range of various appliances almost in every household, office, plant, but not necessarily all of them are emitting dangerous amounts of energy. According to the researches and studies of the scientists there are permissible limits of daily exposure to EMF. Gauss Meter can help to detect whether the limits are exceeded or not, and what changes should be carried out in order to improve the ambient atmosphere. It may be applied for both, testing new devices for compliance with the regulations and safety norms, as well as monitoring the condition of those that are in operation and constant use.

Gauss Meter gives help in detection of magnetic flux density and is sensitive to any change in the magnetic field. In other words, it defines the “power quality”. Thus, by using Gauss meter you may find out the reason, why the monitor of the computer is jittering from time to time and the electrical devices work with interruptions or in an unusual way. Since Gauss meter measures EMF strength, it can also be applied for checking the strength of particular magnets in order to select the one appropriate for your application.