Andrew's Week 9 Progress Report

This week I continued to work with Ashley to callibrate the VRMS reading from the ADE7763.  I also began to work on the IRMS callibration.  First I determined the maximum current present in our circuit which should be no greater than a 60A spike.  Next I used this value times the shunt resistance (.2mOhm) to determine maximum signal level which is .12mV.  Now that the maximum signal level is determine using the ADE7763 datasheet we set the gain for channel 1 to 16 in the gain register since this is the largest gain available and does not push us over the maximum limit of 500mV. 
To verify the operation of the shunt resistor I built an inverting amplifier with gain of -100 using an LT1013 op amp.  Next I used the 200W lightbulb (known source) to examine the waveform at the output of the amplifier when the light is on and off.  Shown below are waveforms at the output of the amplifier.

Output with no load connected.

Output of amplifier with 200W lightbulb connected.

Waveform immediately after closing switch turning on the lightbulb.


Ashley and I also continued to work on the Ethernet trying to connect between the board and her computer using a crossover cable.  We were unsuccessful in all our attempts to "ping" the ethernet chip before the connection timed out.  Shown below is a picture of the overall circuit.

This week Ashley and I plan to continue callibrating the IRMS reading as well as the Active Energy.  Now that we have been able to callibrate RMS voltage we are feeling more confident about continuing to callibrate these more complicated measurements.