Egptos,
Since you want to measure the waveform at frequencies up to 10 kHz, you will need to sample at 10 to 100 times that rate, depending on the complexity of the waveform. With the PCI-6221 you could sample 2 channels (voltage and current) up to 125 kHz which would give you about 12 samples per cycle at the high frequency end of the range. This is the equivalent of sampling about every 30 degrees of phase. If that is good enough to give you the waveform information you need, then the PCI-6221 will be good enough. If you need better timing resolution, you will need a faster DAQ device.
The next issue is how to sense the voltage. Resistor voltage dividers can be used since you do not need isolation. You need resistors which are rated for the voltage and which have low enough capacitance that they do not filter the high frequency components. You should also add some protection devices, such as diodes or varistors to protect the DAQ device and the computer in the event of a failure in the divider. Capacitive dividers may be an option also, but the wide frequency range may be a factor making it difficult to get good performance. I am not familiar with the market for high voltage dividers, so when you search, keep these issues in mind.
Sensing the current involves some of the same considerations. If you can insert a shunt resistor in series with the load on the ground side, then a 50 ohm, 1 or 2 watt resistor might be all you need. Use a non-inductive resistor so that its impedance does not rise at the higher frequencies. If you cannot break the circuit, then you need to look at non-contact current sensors. Hall effect sensors might be fast enough. Standard current transformers may not have the bandwidth you need - at both ends. Current probes designed to work with oscilloscopes may be a good option. Not cheap but probably have the bandwidth and are easy to use.
Lynn
