Hi all - first post so go easy on me!
I've been familiarising with the products and really like what I see but I'm curious to know whether I can measure power consumption of specific appliances, ideally over RF. e.g. a washing machine/dryer or a fridge.
One way to do this would be to run long extensions to CT clamp sensors which would be feasible in some applications but not all.
Many thanks,
Richard
Re: CT clamp AND 13A socket sensor
If you are considering a single appliance, then you should not be looking at our standard split-core CT, but a more sensitive one, and probably a ring-core since you will be able to thread a wire through the core (as Robin does for the CT that monitors the diverted energy in his design of diverter). Plus you can increase the sensitivity by having a multi-turn primary winding and by changing the burden resistor. There's no reason to use the standard "shop" CT if you don't need 100 A and you don't need a split core, but be prepared to work out your own calibration factor!
Re: CT clamp AND 13A socket sensor
Hi - many thanks.
Has anyone any further experience doing this?
It sounds like I would need an emonTx (if in addition to another then assigned a different Node ID?) close to the appliance, and would have to make up an in-line adapter to 'split' the 3-core flex / 13A power plug/socket in order to isolate the neutral or live for a more sensitive, calibrated CT clamp.
It sounds like the calibration process is something I'll be able to work out, but would it definitely be necessary to install a dedicated emonTx near the appliance or are there any 'simpler' CT sensors available (with RF interface)?
Re: CT clamp AND 13A socket sensor
A 'mains adapter' plug-in style instrument is something that's been discussed a few times, but I'm not aware that anyone has successfully done it. That's probably because there are serious safety issues, which we craftily get around by using approved voltage and current transformers as our sensors. There are many dedicated metering ICs available, but as they require direct galvanic connections to live conductors, they pose problems during development, testing and use that make them potentially lethal in untrained or inexperienced hands; alternatively if produced commercially as a finished item, then the required testing and certification process for CE marking would likely mean that the idea was not viable. If you stay with components that carry the appropriate certification, you end up with something that is relatively large and not very convenient.
Re: CT clamp AND 13A socket sensor
Interesting... Thanks Robert for the thorough info there.