04-20-2019, 02:46 AM
Hi, just thought I would post an update on the power bars which are coming along nicely but I did have a couple set backs. First when I designed the circuit board I forgot about the transformer required to monitor voltage, downside to this is the smallest available is quite large but it still fits.
I've been doing lots of variations and testing for the current monitoring, I'm pretty happy with how it's coming and think the accuracy will be ok. The readings are all stable and when comparing to my off brand kill-a-watt meter and regular volt meter the amps always match or definitely close enough. When comparing AC voltages I believe the kill-a-watt is wrong as my setup matches my volt meter which I trust.
Now when it comes to power factor this one doesn't always match up with the kill-a-watt and I have nothing else to compare so I'm not really sure which is correct. Some things match up and some are off by maybe .2. I'm basing mine off the popular OpenEnergyMonitor instructions for an Arduino so I'm fairly confident things are as good as they can be at this price range.
I've gone through a few different current transformers as I'm not really happy with the low end scale, anything under 5 watts doesn't really show up so I've ordered some more parts which should be here Tuesday and I will see if this can be improved. So I haven't nailed down the final design yet but it should be this week.
With that said I don't think it will be the most accurate, I'll say within 5-20% depending on the load, better accuracy with higher loads. In the end there's no way for me to really know without expensive equipment but don't let this worry you. Is it really that bad if a device truly drew 150w but this said 140w, obviously the cost shown over a month would be off some but the main purpose to monitor equipment is still achieved. I only mention this because I don't want to oversell it and say it's the most accurate but it's definitely within range and works well.
A bigger issue I'm having is with the SSR's, they work good but if pushing 4 amps they start to warm up more than I would like, still can touch easily but I want less. When pushing 7 amps through them they get way too hot to touch so I've ditched them and have been researching TRIAC's which is essentially the same thing. It's added more work for assembly but I'm happier using this approach vs an SSR as I don't know what's inside the SSR, building my own I can be sure all the components are high quality, over rated and have the proper safety ratings. I should have the final design finished this coming week and will post details then.
For the software this is what I'm doing for now, more related features will be added over time.
If the software detects power monitoring and you visit the screen to turn an outlet on/off manually you'll get the following view. The watts for each outlet is shown under the outlet icon and a summary for the overall power bar is shown at the bottom.
The controller will tally daily and monthly totals which will auto reset and the data will go into a graph which can be viewed for either. It'll also run an overall total which can be reset any time. Later I'm going to have a list in a spreadsheet view that will show daily and monthly totals as well so you can easily do comparisons over time. I'll break this down into outlets and overall power bar views.
If you touch the "Rate" you can change it and press and hold the total section and it'll reset as well.
![[Image: Main_AC_Manual.jpg]](https://www.robo-tank.ca/image/catalog/slideshow_V5/Main_AC_Manual.jpg)
The screen below is a view you can access from a shortcut on the home page. This shows all the totals for each outlet. Unfortunately I couldn't get all 8 outlets on one screen so added a button to toggle between outlets on a power bar and another button to view a different power bar.
The "Rate" shown here and above is all the same, if you change one they all change, I only show it for each outlet because it fits.
The green "Set Range" box can be used to setup alerts, when you press it you get the next image.
![[Image: Main_Energy.jpg]](https://www.robo-tank.ca/image/catalog/slideshow_V5/Main_Energy.jpg)
This screen allows you to setup an alert for each outlet. If an outlet is turned on and the power being drawn doesn't fall in this range you will be alerted. Sorry the "home page notification" alert won't work yet, it's still coming.
![[Image: Main_Energy_Alert.jpg]](https://www.robo-tank.ca/image/catalog/slideshow_V5/Main_Energy_Alert.jpg)
The scrolling parameter box on the home page will also have the option to show the total power consumption, etc... for a power bar.
That's all I have for now, if you have any suggestions let me know.
I've been doing lots of variations and testing for the current monitoring, I'm pretty happy with how it's coming and think the accuracy will be ok. The readings are all stable and when comparing to my off brand kill-a-watt meter and regular volt meter the amps always match or definitely close enough. When comparing AC voltages I believe the kill-a-watt is wrong as my setup matches my volt meter which I trust.
Now when it comes to power factor this one doesn't always match up with the kill-a-watt and I have nothing else to compare so I'm not really sure which is correct. Some things match up and some are off by maybe .2. I'm basing mine off the popular OpenEnergyMonitor instructions for an Arduino so I'm fairly confident things are as good as they can be at this price range.
I've gone through a few different current transformers as I'm not really happy with the low end scale, anything under 5 watts doesn't really show up so I've ordered some more parts which should be here Tuesday and I will see if this can be improved. So I haven't nailed down the final design yet but it should be this week.
With that said I don't think it will be the most accurate, I'll say within 5-20% depending on the load, better accuracy with higher loads. In the end there's no way for me to really know without expensive equipment but don't let this worry you. Is it really that bad if a device truly drew 150w but this said 140w, obviously the cost shown over a month would be off some but the main purpose to monitor equipment is still achieved. I only mention this because I don't want to oversell it and say it's the most accurate but it's definitely within range and works well.
A bigger issue I'm having is with the SSR's, they work good but if pushing 4 amps they start to warm up more than I would like, still can touch easily but I want less. When pushing 7 amps through them they get way too hot to touch so I've ditched them and have been researching TRIAC's which is essentially the same thing. It's added more work for assembly but I'm happier using this approach vs an SSR as I don't know what's inside the SSR, building my own I can be sure all the components are high quality, over rated and have the proper safety ratings. I should have the final design finished this coming week and will post details then.
For the software this is what I'm doing for now, more related features will be added over time.
If the software detects power monitoring and you visit the screen to turn an outlet on/off manually you'll get the following view. The watts for each outlet is shown under the outlet icon and a summary for the overall power bar is shown at the bottom.
The controller will tally daily and monthly totals which will auto reset and the data will go into a graph which can be viewed for either. It'll also run an overall total which can be reset any time. Later I'm going to have a list in a spreadsheet view that will show daily and monthly totals as well so you can easily do comparisons over time. I'll break this down into outlets and overall power bar views.
If you touch the "Rate" you can change it and press and hold the total section and it'll reset as well.
The screen below is a view you can access from a shortcut on the home page. This shows all the totals for each outlet. Unfortunately I couldn't get all 8 outlets on one screen so added a button to toggle between outlets on a power bar and another button to view a different power bar.
The "Rate" shown here and above is all the same, if you change one they all change, I only show it for each outlet because it fits.
The green "Set Range" box can be used to setup alerts, when you press it you get the next image.
This screen allows you to setup an alert for each outlet. If an outlet is turned on and the power being drawn doesn't fall in this range you will be alerted. Sorry the "home page notification" alert won't work yet, it's still coming.
The scrolling parameter box on the home page will also have the option to show the total power consumption, etc... for a power bar.
That's all I have for now, if you have any suggestions let me know.
