PrePaid meter energy pulse logging

I have a 3 phase prepaid meter at home (model: ACTARIS ACE 9000 ITP).  It has a little red LED that blinks at a rate of 1000 impulse per 1 kWh.

This if I measure the time between pulses I will have instantaneous consumption in Watt where:

W = 3600/t
t in seconds
W in Watt

Below are two screenshots. We can see a couple of things:

  • In the first we can see that the pulses are almost 100ms in duration.
  • After I had a bit of hot water out of a tap, the geyser switched on and there was a time of about 700ms between pulses, thus 5.14kW (3600/0.7)
  • because the pulses are 100ms (and there has to be at least a little time between the pulses), the max power that can be measured is just a tad over 35kW



for this I used a phototransistor (Vishay TEPT4400) that has a good gain in the red part of the light spectrum… with a max spectral sensitivity at around 575nm and matched that with a 100k pull-up!