Hello,
I suggest you use an Arduino Due. It has a higher analog to digital conversion rate than an Arduino Uno or Mega, more memory and multitasking capability.
You shouldn't use LIFA or LINX for this project. You need to transfer data in blocks to Labview. Using LIFA of LINX to transfer an ADC readings one sample at a time reduces the conversion rate to 500 samples or less per second. You need to use a zero crossing detector and interrupts to trigger the start of a sampling sequence. The standard versions of LIFA and LINX do not have interrupt capability
Ideally you should use a micro controller with dual simultaneous analog to digital converters to measure power. But Arduino micro controllers only have one ADC. To get around this limitation you need to first sample the voltage waveform and then the current waveform. To preserve the phase difference information between the voltage and current waveforms the two ADC set of readings need to be triggered to start at the zero crossing of the voltage waveform. This is why you need a zero crossing detector and interrupt capability. You need to sample the voltage and current waveforms for an integer number of periods and the same number of samples for both the voltage and current t waveforms. One thing that can be done ease the requirement for a high sampling rate is to sample the waveforms for a prime number of periods. For example instead of taking 250 readings in one cycle you could take 50 reading per cycle for 5 cycles. The method described in this paragraph will only work for steady state conditions. For transient conditions you need dual simultaneous analog to digital converters.
The zero crossing detector is also useful for measuring sag. By measuring the amplitude of the voltage waveform 1/4 ad 3/4 of a period after a zero crossing has occurred you can determine if the voltage amplitude has sagged.
Two possible methods for determining if there are spikes on the power line are:
1. Use a high pass filter, a rectifier, a voltage clamp circuit, a comparator and a hardware counter to count the number of spikes.
2. Or if you need to know wen the spikes occur use a high pass filter, a rectifier, a voltage clamp circuit, and a comparator to produce an interrupt when a spike occurs.
The low frequency cutoff frequency of the high pass filter should be between 2 to 5KHz.
To keep from creating a short circuit when you connect your power quality analyzer to the power line you need, as a minimum, to use difference amplifiers to interface your your analyzer to the voltage and current sensors .
hrh212
