Hi,
Is it possible to monitor 10 clamp inputs via this system. I would like to monitor all breakers in my main box separately to get a better understanding of the usage patterns.
Glenn
Monitoring 10 Clamp inputs
Submitted by Guest on Mon, 08/07/2013 - 21:55»
Re: Monitoring 10 Clamp inputs
Welcome, Glenn.
Which system - hardware or software, or both?
The emonTx has 3 current inputs for c.t's, so you would need 4 emonTx's to give you 12 current inputs in total. Alternatively, you could use an Arduino-based construction with something like the Mega 2560 (which I believe has been used by others) with the input circuitry on stripboard, or you could put everything on stripboard.
You need at least 11 analogue inputs (10 for current and one for voltage) if you wish to measure power accurately, assuming you are in the UK and have a single phase supply.
The emonLib library, Raspberry Pi and emonCMS can all handle that many inputs, but you will probably not be able to measure all the inputs continuously. The standard library methods sample the inputs in turn for a short time - normally 10 cycles - so the best you could hope for is a reading every 2 seconds for each channel. Normally, inputs are sampled every 5 s so that should not represent a major problem.
Re: Monitoring 10 Clamp inputs
Hi,
that's exactly what I am looking for. I am planning to build a hardware for this for quite a while now bit got stuck. The problem why I do not use the emonTX is that space is limited in my wallbox, the wallbox is next to my homes door in the hall (WAF-PCBs outside of the wallbox are not acceptable) and I see a problem with distributing the "alien wires" of the current transducers through the wallbox and then outside of it (VDE 0100...). I already have an idea how to do that but my experience in analog signal routing are limited. See http://www.elektor-projects.com/project/multi-channel-isolated-smart-energy-meter-for-distribution-board.13322.html where I posted my idea of how to do this.
If anyone of you can help: I am planning to release this as open source as well.
CYA,
Markus
Re: Monitoring 10 Clamp inputs
BTW.: The "hot side" of my idea above is only ment for those of you who are certified electricians (VDE 0100... etc) like myself who are knowing what they do! Please be careful when handling high voltages! But since the sensor board will be fully isolated the FPGA/µC "cold side" will be no problem for anyone!
Re: Monitoring 10 Clamp inputs
We recommend transformers - current and voltage - for isolation for exactly the reason you warn about high voltages. I don't know the VDE standards so I cannot help you with those. Alternatively, is it possible to intercept the wires outside of the distribution board and have current transformers outside?
If you are looking to design a circuit board, there is some good information about safety requirements here. The designer is another Chartered Electrical Engineer so I think he knows what he is doing.