Our voltage signal is same like our heart beat signal. We dont want any changes in both the signals For heart beat signal, it was said in literature that video recorded by a single RGB camera is good than sensors type.

So, I prefer video recorded by a single RGB camera contactless monitoring.

The contact less monitoring is accomplished by hall generator based on the Hall effect where a semicondcutor slab with current passing in it will sense the magnetic field incident on it produces a voltage called the Hall voltage which is proportional to incident magnetic field.

Also one can use current transformers to sense the current passing in wire or circuit. But this current must be time varying current.

I think the hall generators are more suitable than the current transformers since they respond also to the DC current.

Best wishes

Dear colleagues, thank you for the valuable advice!

Несомненно датчик Холла, особенно на полупроводниковой основе является одним из самых популярных датчиков бесконтактного мониторинга тока, также напряжения. Однако эти датчики также очень чувствительны к воздействию внешних паразитных магнитных полей.

Undoubtedly, the Hall sensor, especially on a semiconductor basis, is one of the most popular sensors for contactless monitoring of current and voltage. However, these sensors are also very sensitive to external spurious magnetic fields.

Using RGB cameras is also a good and interesting idea. You will need to somehow try to conduct an experiment.

In recent years, the use of sensors based on the magneto-optical Faraday effect (magneto-optical transformer_) is considered promising. However, the implementation of this principle in laboratory conditions will be very difficult.

Dear Islam,

welcome,

It is true that the Hall devices are sensitive also to interfering magnetic field but this magnetic field can be suppressed by proper screening the hall generator from the foreign magnetic field.

I think the sensors must be as simple as possible and also linear. The use of optoelectronic elements may complicate the sensing process.

Best wishes

Dear Professor Abdelhalim Zekry!

Thank you very much for your very helpful tips and comments. In fact, in laboratory conditions, I experiment with Hall sensors manufactured by various companies in integrated circuits version. And it gives a pretty good effect. But these sensors are sometimes sensitive to interference created by economy lamps.

I agree with your proposal in that it is necessary to create a special design. May be similar to mirror antennas. Then it is sure to provide focus and locality.

Are you talking about DC or AC voltage?

In principle, I am interested in both.

Thank you for the answer!

For AC what is used is AC High Voltage Measuring Capacitor Divider (usual at High Voltage ) - not sure whether we can call it 'contactless'.

DC electric field and therefore voltage can be sensed using mechanical or solid state varactors :

https://patents.google.com/patent/US9664721

I agree with your response option. But still, as you yourself noted, it’s unlikely that these options can be considered contactless

As far as I know the only contactless way of measuring the E field in the neighborhood of an electric circuit is by means of optical sensors. The spectrum of the one described in the attached file starts at DC.

While current sensors employing a ferrite ring deliver a signal whose dependence on the current is exclusively determined by the sensor itself, the problem with these optical E field sensors is (apart from the costs) that obviously, to calculate the voltage based on the measured strength of the E field one has to take the geometry of the circuit into account.

So, it is relatively easy to calibrate a setup containing a permanently built-in sensor and a circuit of fixed geometry (just apply different known voltages, note down the sensor responses, and later on, interpolate).

But the sensor cannot be used like a voltmeter (just hold it near to two points and read the result), and in order to render meaningful results, the distances between the conductors carrying the electric potentials have to be larger than the diameter of the sensor (6 mm).

Induction gages are used routinely for voltage and current.

Dear Sir Joerq Fricke!

Thank you very much for the informative answer and detailed information about the features, capabilities and implementation of optical sensors. In recent years, I have paid a lot of attention to the study of available literature on such sensors. I just tried to realize such a sensor without additional optical elements (polarizer, analyzer, lens, etc.). However, it did not achieve a significant result.

I will definitely consider your valuable advice in future research.

Dear Jerry Decker!

You absolutely mentioned the induction sensors. However, conventional induction sensors are best suited for measuring displacements. And to control voltage and current, you will most likely have to give such a sensor a transformer structure.

Undoubtedly, a respected professor as a leading scientist in this field emphasized the most popular and modern sensors, which are the most miniature. But naturally, these sensors have a number of disadvantages that limit the scope of their application, especially when measuring extra-large currents and voltages.

Thank you for your valuable reply.