Hi, I am looking for feedback from anyone that has tested dirty electricity (mV-P-P) values using proper Dirty Electricity meters as well as looking at the AC sine-wave output on a on good quality oscilloscope.
I am busy searching for inverter that offer truly clean sine-wave outputs with the least Electro-Magnetic Interference (EMI) and least dirty electricity output possible.
I have a Trifield Dirty Electricity meter and have found extremely high readings off most inverters that I have tested so far. Inverters are notorious for this, in addition the solar array also picks up stray EMF which often gets fed through the system as EMI.
Electro Magnetic Interference (EMI) is also known as Radio Frequency Inference (RFI) and is a disturbance or interference which affects an electrical circuit. This is either through EMF induction, conduction or electrostatic coupling. You will see this as a type of noise if you view AC current as a sine wave on an oscilloscope. Since it can be any frequency and fluctuating the oscilloscope needs to cover a wide range of frequencies and have a very high sampling rate. As an example CFL lightbulbs give off quite a bit of EMI as do many inverters. This can be seen as noise, a buzz or hum even on sensitive equipment. HAM radio specialists often grapple with this.
Ok. Iām more familiar with the term RFI which is more common.
The term ādirtyā isnāt used however. Noisy is the common description.
It is normally measured by total harmonic distortion (THD) which should be referred to on the technical specifications of that device.
Do you have a specific problem wrt noise??
And yes it is a problem what with the chopping up of DC to generate AC.
EMI is broken into two different parts, namely conducted emissions and radiated emissions. You need a good quality spectrum analyzer to measure these emissions. Conducted emissions are typically measured on the grid input to the inverter, and require you to have a very clean, filtered supply so that you can measure only the noise contribution of the inverter under test. A device called a LISN (Line Impedance Stabilization Network) is inserted between the clean supply and the inverter input and has measurement ports for connection to your spectrum analyzer. Conducted emissions are measured up to 30MHz. Above 30MHz you need to measure the radiated emissions, which is much more difficult as you really need an anechoic chamber and a calibrated test antenna. You might have some luck with a reverb chamber, but itās still not something you can easily do at home. The test chamber needs to be completely shielded from outside interference.
Thanks Stanley, I would love to have access to test solar systems as you describe. Especially the Inverters & MPPT controllers. One hack I found was using an analogue AM radio often gives an idea of the severity of radiated emissions and thus also of dirty electricity. Of course I have the TriField dirty electricity meter as will which plugs into an AC outlet to measure EMI in mVp-p. I suspect that with some inverters with an excuse of a sine wave output, that this meter will not reflect accurately.
My goal here is to find equipment where the sine wave output is as clean as possible and where there is very little RFI being generated by the inverter, conducted or radiated. Of course also where EMI/RFI from the MPPT or array of panels is not being fed through.
There are two specific problems. First, I have a few clients now who are experiencing health issues when the inverters are running. These are Electro Hyper Sensitive (EHS) people who have adverse reactions when exposed to EMFās but especially dirty electricity and high frequency RF. Second I have two clients who are experiencing interference on their laboratory equipment when the Solar Backup (Inverter) is used but not from the Utility power.
Iām not much of an expert when it comes to these highly technical issues. I just know that most inverters will use some sort of higher frequency to get where they are going. A Low Frequency design like a Victron Multiplus, uses a 20kHz PWM signal to shape the sine wave, and therefore you will see (on a scope) little steps in the output, which also reflects in the THD (total harmonic distortion), that is, by how much the signal deviates from a clean sine wave.
Conversely, High Frequency designs uses a boost stage that also runs in the range of tens of kHz, some of which will leak out and affect things around it.
When it comes to EHS people, it seems some of them are very sensitive. I heard one story of someone who could not sleep, because the main distribution board to the house was on the other side of the wall to where her bed was. If youāre dealing with this kind of person, I donāt know that thereās anything that will be quiet enough.
RF is not bad for you unless you are exposed to massive RF power from a transmitter. So those folk who donāt want a pylon near their house can argue that they find it an eyesore but not that itās bad for their health.
EHS is abbreviation for Environment, Health & Safety right??
E.H.S. stands for Electro Hyper Sensitive, or people very sensitive to EMFs, its like being allergic to EMF. I suffer from this to a degree and hence have researched and experimented with solutions for a few years now. Having worked technically in the telco industry for decades I understand the dangers of RF (of all power levels).
I help people daily who have health issues from low power RF exposure. The harm is very reaI, I can point you to over 2000 peer reviewed studies proving the harm. With regards to power lines did you know that high-line workers (the guys that maintain high voltage power lines) have very low life expectancy & get danger pay as a result?
Please have a look at The Environmental Health Trust who have cataloged much of this research.
Thanks for that, the radiated emissions from higher frequency designs would be easier to filter out than the step-wave you explain. I have had fair success filtering the higher frequency interference using shielding & ferrite rings of the right compound & girth as suggested by ham radio specialists.
Just to be clear, I am not saying that EHS is not real. A magnetic field passing through a conductor (which all of us, to some extent, are) will induce an electric current, and since our nervous system is kinda electrical, it must have an effect.
I suppose we have some noise filtering on our āinputsā, but some of us probably have less of it.
In my experience, which is basically just talking to people, such sensitivity can be hard to avoid for people with a high sensitivity (being able to feel wiring on the other side of the wall). The strength of the field diminishes as the square of the distance you are away from the source, which means that for the most part, simply being several meters away should do the trick.
I use Electrical Field meters to measure how far the fields extend. Body voltage meters also prove that we absorb these fields. Problem is you touch your keyboard, mouse and other electrical devices so you are constantly absorbing these fields. The lack of earth & metal earthed casings in most appliances nowadays makes them especially bad.
I have created a very low EMF area where I work, even with computers. Its been an interesting learning curve I must say.