Building an energy monitoring system - 3x current circuits, 1x voltage circuit, multile temp and one pulse output

Guys,

I am new to this forum and would like to send out a request for help. I have an ambitious plan to build a monitoring system that can monitor 3x current circuits, 1x voltage circuit, multiple temp. sensors and one pulse output. I also want to access all this data online remotely if possible with graphing capacity. 

I know I have to start with the emonbase but what I am having a difficulty wrapping my head around is which one to go with. Also, if I use the NanodeRF, will I need to have a laptop on site to log all this data or will it periodically send the data to a server? 

Any help in this direction would be greatly appreciated. Thank you in advance!

Sheldon

Robert Wall's picture

Re: Building an energy monitoring system - 3x current circuits, 1x voltage circuit, multile temp and one pulse output

Welcome, Sheldon.

What I think you need is one emonTx, one base and emoncms.org. 

For your base, you can use NanodeRF, OKG base, or a Raspberry Pi. The first two send the data via ethernet to either a local server - which could be your laptop or any (old?) machine that can run Apache, MySQL and PHP, i.e. LAMP/MAMP/WAMP - or emoncms.org. The RPi can function either in that mode as an Ethernet interface or, with attached storage (the internal SD card is not reliable long-term) as a local server.

sheldonmendonca1's picture

Re: Building an energy monitoring system - 3x current circuits, 1x voltage circuit, multile temp and one pulse output

Robert,

Thank you for your reply. I think I will use the  NanodeRF as the base and build the monitoring system to send the data via ethernet to emoncms.org. A quick question - does emoncms store the data? Are there any limits on the amount of storage capacity? 

On the hardware side - can I use rope CT for the current measurement? I need to be able to measure upto 1200A since this product is intended to be installed in Buildings in NYC. 

Thank you once again. I will keep posting results on my project.

Sheldon

Robert Wall's picture

Re: Building an energy monitoring system - 3x current circuits, 1x voltage circuit, multile temp and one pulse output

A quick question - does emoncms store the data?  Yes

Are there any limits on the amount of storage capacity? Not at the moment (but if you're a commercial operation, a donation to the running costs would be appreciated).

On the hardware side - can I use rope CT for the current measurement? I need to be able to measure upto 1200A

As long as you get the interface right, you can use any current sensor. By "interface" I mean the output has to be centred at half supply voltage of your Atmel processor (1.65 V if you use an emonTx, 2.5 V for an Arduino board) and you need the correct burden resistor to give you close to 3.3 V (5 V) peak-peak output at maximum current, or if you're using a Rogowski coil its integrator output voltage must satisfy those conditions. If you're using a conventional c.t. it means it must have a sufficient VA rating (many only give 1 V p-p out).

since this product is intended to be installed in Buildings in NYC.

That is slightly worrying. The emonTx is a single phase unit, designed for the UK domestic supply (usually a TN-S or TN-C-S system). If you need to accurately measure power across three phases (or are they centre-tapped to neutral in which case it's 6?) then it's a lot more complicated than I thought. You need to measure at least 3 voltages - look at Martin Roberts's "Full-fat 3-phase monitor": http://openenergymonitor.org/emon/node/1170.  If you have your own step-down transformers, it may be easier to measure on the primary side.

sheldonmendonca1's picture

Re: Building an energy monitoring system - 3x current circuits, 1x voltage circuit, multile temp and one pulse output

Robert,

Thanks once again for the quick response. I need to do a lot more work before I can make this commercial - just building this out of curiosity. 

I will work on the information you have provided and get back to this thread with more information.

Sheldon

 

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