High Voltage Measurement - Science topic

I tested a quality and sensitive multimeter and it killed barrier in my Caco-2 cells. Most likely that the meters use much higher voltage and use DC rather than the micro-volt AC that the TEER machines use. Even then, the numbers that it was giving were way off what my TEER machine was giving, despite my confirming the performance of the multimeter with store-bought resistors.

Dear Ju Cheng ,

In addition to the tests outlined by Joerg Fricke you can use the tests brought in the paper at the link:https://www.idc-online.com/technical_references/pdfs/electrical_engineering/High_Frequency_Power_Transformer_Measurement_and_Modeling.pdf

To see the list of the specifications of the flyback transformer please refer to the paper in the link:

Best wishes

Dear Tarik,

I would say that your question is not well posed, in that you use the term SNR for power distribution networks, but then probably you mean the distortion of the network with respect to a sinusoidal reference, i.e. Harmonic Distortion first of all, whereas I would use the term "SNR" for the measurement of voltage or current. The measurement quality, as measured by SNR of the read quantities, depends of course on the measurement system, e.g. transducers, data sampling (so number of bits of the ADC, oversampling, averaging), post processing methods ... a lot of things for one question.

Assuming that you wanted to speak of distortion of network, then as you say we may distinguish between voltage and current: a load is connected to a distribution network, this load absorbs distorted current (such as a 3-phase rectifier), that is characterized by some harmonic distortion: there are limits for individual harmonics (IHD) and for the total harmonic distortion (THD). A good reference is the IEEE Std. 519 (I attach its Table 2); as you see limits are given depending on the short circuit current ratio, that is the largest the ration, the stiffer the network, so the lower the impedance offered to the load and its current, and the lower the caused network voltage distortion.

So, we come to the voltage quality: it depends on the combined effect of all distorting loads and the amount of installed power. Usually, there are not real limits for normal loads in terms of voltage distortion (they are expressed in current, as we see above), but they are "guaranteed" a voltage with some quality, so low distortion. A standard for this is the EN 50160, but IEC 61000-2-2 is more instructive and complete (I attach its Table 1).

To conclude, when you have the amount of individual harmonics and the THD you can also calculate the SNR, because you interpret the harmonics as noise (that is not, from a signal processing standpoint, and not only that). The reciprocal of the sum of squares of the % limits gives you the SNR in power; taking the square root it will be in amplitude.

There are many references for values of network distortion or Power Quality assessment. Personally I measure Power Quality in electric transportation systems (railways, metros,...) and you can find some refs of mine.

Salam aalaykum

You can found many informations concerning this field published by Dr Farid Dawalibi in IEEE.

Hi Youcef

I suggest to use a low frequency filter (LC circuit) with high voltage inductance and capacitor which could help you to eliminate odd harmonic components.

Good luck

Personally, my research works are based on the IEC 60502 standard which I highly recommend it for you (Power cables with extruded insulation and their accessories for rated voltages from 1 kV (Um = 1,2 kV) up to 30 kV (Um = 36 kV)) ... best regards

maybe i can help you but need more explanation what you want exactly!

It is important to see the waveform recorders in failure to analyze the characteristics of the fault. In transmission lines to equal or higher levels of 230 kV, the angle between the voltage and current is a good indicator of the fault impedance (type).

Some elements that can cause these types of failures are:

- Approach with other low voltage circuits .

- Approach with vegetation

- Failure arrester

- Contamination in electrical insulators

Dear Mohammad

you can try MATLAB, PSCAD, EMTP-rv, Neplan

good luck

See, "The Density, Pressure, and Particle Distribution in a Lightning

Stroke near Peak Temperature" by Martin A. Uman, Richard E Orville, and Leon E Salanave in the Journal of Atmospheric Sciences, Volume 21, May, 1964, pp 306-311.

Uman, et al, estimate the average temperature  to be 24000K and a peak pressure of 18 atmospheres. 

There is another method, called electrostatic  field mill.

Also you can try this link. It seems to measure static Fields:

When the thyratron is ON, the voltage on its anode is close to 0. The HV of 30 kV is applied mainly to the charging resistor (or inductance) - inside the HV unit. All is in accordance with Ohm's law. Generally, a limiting resistor (limits the current of HV device) is always present in such systems.

In our similar experiments (preionization of the channel for a main discharge), the allumina walls get chared (3mm Inner Diameter). Which results in some ablation of the material and such effect  adds measurable amount of added pressure and contaminants to the plasma channel. 

A ballpark answer is 1 micro henry per meter for single conductors.  Parallel conductors are lower as would be the case for two inductors in parallel.

More complicated answers are addressed in the papers already listed.  In a High Voltage lab, you don't generally have high currents unless there is a flashover.  In all cases, common sense is a great asset to figuring this out without complicated evaluations.

Dear Praful Patidar,

You have written that your simulator demands the values as input for Primary side R1 and L1,secondary side R2 and L2,Magnetization Rm and Lm,Nominal power and Frequency. But as you know the reactive part i.e L1, L2, Lm are not linear over the entire range and near the operating region of transformer the magnetizing current hence primary inductance is nonlinear in nature please checkup whether your simulink consider this aspects or  you can train your simulink program with the nature of nonlinearities near the operating point. To determine the impedance voltage and leakage reactance you need to input more parameters. Please also  remember that a transformer design (insulation coordination) is never complete unless you consider the capacitance distribution in the winding's particularly for HV winding. So I think it will be better to consult a software where these aspects are considered or develop a software which can be trained to deal with all these aspects. May be you need to use Artificial Neural network and  designing the software may not be that easy 

Thanks Remi

THank You 

Suhaib Salam Alani  Sir...................

Partial discharge is expressed in pico Coulomb a unit of charge. Now q=C.V where q= charge C = capacitor and V is the voltage across the capacitor. Again dq/dt = C.dV/dt is the current which is displacement current and rate of change of voltage in the matched impedance connected in series with this capacitor also depends on the on this displacement current and the impedance characteristics of the matched impedance. For 50/60Hz supply voltage the voltage drop across the matched impedance is insignificant as the frequency response of the impedance is tuned to the expected bandwidth of PD signals. It is the further filtered with a band pass filter. So all the displacement current for which bandwidth is beyond that of PD signal is supposed to be suppressed by the filter. There are some soft method using WL or ANN technique for eliminating this unwanted signals. As per your exp it is found that you are working with Impulse Voltage so in the sloppy part of the current wave form lot of High Frequency noise(?) is observed. To eliminate the overlap of this this displacement current components one must check the bandwidth of this components during the sloppy waveform. After that one can interpret how relevant those components are and then it can be filtered out by using band filter circuit.