[chbot] Fwd: Raspberry Pi etc.
zl3custarr at gmail.com
Tue Aug 17 08:29:28 BST 2021
Thank you for including me as a member.
I was the person that asked for help regards using the Raspberry Pi for
logging electrical data.
As I thought I might be chatting only to a few people, rather than the
whole group, I did not have anything prepared.
Thank you for the suggestions. As mentioned it was too much for me to
remember everything so please also inform me using this list. (Or use my
email address zl3custarr at gmail.com )
Please see below more info.
USING A RASPBERRY PI FOR LOGGING ELECTRICAL QUANTITIES
17 AUGUST 2012
The idea for this came about at my brothers place where it was thought
that maybe due to an “unseen” water leak the water pump would be
operating at “regular” intervals and therefore consuming electricity.
For this to be checked the best place to monitor the pump circuit is at
A clip on a.c. current sensor would be the best option for detecting
when the pump was operating.
For this to be logged, the current sensor could drive a 4N26 opto
isolator along with a storage capacitor arrangement on its output, to
provide a constant signal to the Raspberry Pi’s input while the current
was flowing to the pump. Note this would not provide a value of current,
instead just the indication that the pump was on or off.
The Pi would be required to log this on/off state, at regular intervals,
say 1 minute, along with a time/date stamp. Therefore the Pi would need
to populate a suitable spread sheet with this data.
Mark, I think you had some suggestions on this so I would appreciate you
Peter Harris suggested I look at Openenergy Monitor which I have done
and I have found a suitable circuit for the current sensor arrangement.
Another idea that I am looking at is to be able to check the times that
a water heating circuit is enabled. This would only need a 230V coil
relay with a NO contact connected between a Pi supply and one of its
inputs. This would also require another column to be populated in the
In the future:
I am also thinking that it may be of use to record the values of current
and voltage. Again a spreadsheet would be needed which could also have
columns for power and, using integration, kWh. I guess an Arduino would
be simpler as it has built in A to D conversion, however as I already
have the Pi I will persevere with it at this stage. Just looking at the
drawing for the current sensor for the Arduino;
it looks as if the software determines the peak value and from there
calculate the RMS value. I assume the voltage RMS value will also be
calculated using the peak value as well. I have heard that the scan rate
of the Pi is slower than the Arduino so I wonder if this would have a
bearing on the Pi’s ability to determine the peak value.
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