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Dolev company with a unique method for lowering the magnetic field (radiation) around populated areas is an active shielding method,
With this method it is possible to limit the magnetic field of the source wave by using the creation of another magnetic field which is the same in magnitude as the original magnetic field but opposite in direction.
These inverted fields are usually created by electric currents that flow to active coils, these coils create the magnetic field in the opposite direction to the direction of the source wave.
The active shielding is effective in limiting radiation (magnetic fields) in the vicinity of overhead / high voltage lines, since these power lines are a uniform source of radiation and only change according to the current flow of the electricity company

What is the active protection system?

active shielding system, a square loop must be produced that conducts a current and thus will actually cause the development of a magnetic field in the conducting loop,

The active shielding system depends on the characteristics of the offending field and the ability of the system that produces the opposite field to meet these characteristics so that a significant attenuation of the field is obtained.
Figure 18 shows a simulation of the magnetic field that develops on a high voltage line as a function of distance, the high voltage line is a 400kV medium L12 type line, capable of three-phase T-ryb/byr configuration, the measurement height is 1m from the ground and below are the simulation results:

From the result of the simulation it can be seen that the maximum magnetic power obtained in the high voltage line is 12.185uT, at a calculated distance of about 10 meters from the power line the simulation results are 9.55uT and at a calculated distance of about 20 meters from the power line the simulation result is 4.62uT.
Figure 19 shows a Matlab simulation of the magnetic field strength that the system must provide in order to land the source wave to a strength of about 2mG (the magnetic field strength recommended by the IRAC organization) at a distance of 20 meters from the source wave,

According to Figure 19, it can be seen that the simulation results indeed yield satisfactory results at a distance of about 20 meters from the high voltage line.

Figure 21 shows the working principle of the active protection system:

The installation of the system requires preliminary preparations, Dolev Electromechanika Company performs all the theoretical engineering preparations, among other things, performing the analysis of the area designated for shielding against magnetic radiation and performing measurements in order to know where the measurement sensors should be placed in order to give the system maximum efficiency in lowering the field to the accepted values. As well as all the constructive planning of the system components with an emphasis on the Electricity Law and municipal by-laws

Measurements before and after the implementation of the active shielding:

the measurements presented were performed before the implementation of the active system and after its implementation, the measurements were performed using equipment for direct measurement of a low-frequency magnetic and electric field when the measurement was performed under conditions of maximum current consumption in order to estimate the intensity of the radiation and the effectiveness of the shielding for the worst case.

Measuring equipment:

radiation risk meter made by PMM company model EHP50C, for the frequency range 5Hz – 100kH.
The measurements shown are calculated measurements that were performed using the active shielding system where the magnetic flux levels before the application of the shielding are the actual levels and the magnetic flux levels after the application are the levels that the system will be able to reach given the nature of the system’s calibration.
The first calculated measurement that is shown was performed in the northern part of the building in front of the center of the high voltage line at a height of 1 meter above the ground.

Dolev is the only company in Israel that can provide an active protection system
For radiation from high voltage lines of an electricity company

In Israel, 10 active protection systems have been established since 2007