Friday, 31 October 2014

Monitoring Energy usage with the LED Pulse Sensor from Crucible Technologies

With winter coming, and all the energy scares in the news, I was keen to start monitoring the power we were using. I had always intended designing my own system with the LED Pulse Sensor and the Raspberry Pi, but had never got round to it. So I thought I'd quickly rig up soemthing using the Meter Logger from Crucible Technologies. Took me around half an hour to set it all up.

The most common way to monitor energy usage in a home is to use a clamp round the main cable and connecting this to a meter. There are a couple of disadvantages with this approach.

One is accuracy - the clamps measure current but do not measure voltage - they just take a guess at it. Also if the current and voltage are not in phase, this introduces another inaccuracy. The clamps themselves have a tolerance about 10%. Overall this approach can overestimae usage by 20% according to this report. The other is that is qute hairy trying to force a clamp round the mains cable.

The LED Pulse Sensor is easy to fit and is 100% accurate as it uses the billing meter information. Here is one fitted to our meter. It did take a bit of trial and error to position the sensor EXACTLY over the LED pulse output of the meter. (There is a green light on the Meter Logger that toggles every time it gets a pulse from the LED pulse sensor. This is useful feedback during alignment - it is important to get this right as you dont want to miss any pulses).

Here are a couple of images of the 2-core cable (I just used cheap speaker wire) coming out of the meter cupboard and into the house. You just have to maintain the right polarity. The more negative side of the LED pulse sensor has a black line on the wire.

The next step was to connect the cable to the Meter Logger. This comes with some nice 2 way plugs which is quite easy to wire the cable into. The more negative side of the wire goes to the right.

The problem I had was that my broadband router was the other side of the house - 3 rooms away. However the nice people at Solwise sell a HomePlug which allows you to use the mains wiring to extend your network to the other side of your house. Very very easy to use - just plug and go. I just added a small 4-way extension lead which had the 5V PSU for the Meter Logger and the HomePlug. You can see the Network cable plugged into the Meter Logger and the HomePlug.

I was all set now. All I had to do was to go to my PC and start looking at the energy usage. Crucible Technologies provide a nice utility called "LoggerFind" that easily finds the Meter Logger on your network and provides the IP address. Just click on this to view the webpages provided on the Meter Logger.

Here is the screenshot of my consumption so far for today (31st October 2014). Nice and low so very happy (till the washer and/or tumble dryer starts up!).


I know that doing my own software for the Raspberry Pi would be cheaper - but would have taken a couple of days of programming and debugging and in all reality not got done. So the off the shelf solution from Crucible Technologies was great - total install time of less than 30 minutes. It also has the facility to e-mail me daily or weekly data.

A bit expensive at nearly £150 for energy monitoring in residential applications but easily affordable for small businesses. It also has three seperate pulse inputs which can used for multiple electricty meters in a unit with multiple occupants OR to monitor water and gas meters. Some utility meters have an electrical pulse output, so you would not need to use a LED Pulse Sensor.

1 comment:

  1. Hi, I am looking for this information. Thanks its really helpful. Can we have the data records for every minute? thanks