Hi,
I hope there is some electrical engineers or folks with good knowledge and understanding of electricity, if not, can you point me to some good electro forum? Even though I would prefer to solve this here “at home”
I am not so happy with its accuracy, I must say 99% accuracy is marketing BS. If I knew that, I would go for more intrusive solution (inline wired meter)
The main issue is my induction cooking hob, which is confusing the clamps as it has switchmode powersupply, and is not sinusoidal (according to google explanations of various people with same issues). It shows 100W usage in standby, but real usage with plug-in power meter is 5W. OK, I solved this via simple rule that deducts 100W from the load, but thats not the only issue here…
First, specs:
I have 3 phase 4 wire system in my apartment, where load is distributed on red, yellow and blue phases. All load is single phase 220V, there is nothing that is using more than 1 phase.
I’m using HEM with 3 clamps.
Now, first question that I have:
I did not install this device according to manufacturer specification.
The device comes with 3 power supply wires and demands to be wired directly to the live mains (on the input of the main breaker) of all 3 phases. so each clamp should be powered from a different phase lets say.
I did not want to do that, if I wanted to connect something to the live mains, I would go for something more reliable then clamps.
So I wired all 3 power supply wires to the normal power socket plug on phase1 (red)
I realized that HEM is reading power grid voltage through his power supply, even with the clamps disconnected he knows voltage is 237.2V at the moment.
So I am hoping that this is the only reason why they want it to be wired to all 3 phases, to get the accurate voltage reading for each phase? I don’t care if other phases are 236.9V at the moment, I can live with this margin error.
This is the part where someone with real knowledge can say yes you are right or no, totally wrong install.
One more question about clamp direction - clamps have " K -> L " symbol, dunno what is K, but L stands for load I guess and arrow should point to the direction of the Load if I understand correctly. Anyway I have mostly good and positive reading for 90% of the load, so I assume direction is correct…
Other than induction hob, I have found few lights (some KNX dimmer, some KNX 12V spotlights) that do not show any change or go to negative value! like, load reduces 7W when I start the light.
Also, kitchen exhaust hood fan shows minus 50W on one phase when started!
All other load behaves normally, shows normal positive values on their respective phase when started (some are pretty accurate when compared to plug in power meter).
With all these issues I dont trust this meter at all, I am not confident it will give even close results in kwh as the power company.
Is there anything that can be done to solve these issues? Or just live with it?
I understand that it works best with pure resistive loads with power factor 1
So, induction hob, inductive load, not good for HEM. Kitchen exhaust fan, washing machine - electromotors, not good for HEM.KNX dimmer - doing crazy stuff with electricity to reduce light, confuses the clamps, again not good.
looking forward to your thoughts