"Grunff" wrote in message
...
Hi all,

This would probably fit better in another NG, but I know quite a few
people on here who will be able to provide some good ideas, so here goes.

I have an experiment where a voltage of ~250 VDC is applied across a load,
resulting in a current consumption of around 2A. The experiment runs for
around 5 minutes.

The nature of the load is such that the current consumption is very
spiky - it may average to around 2A, but you get very short, sharp spikes,
probably of 10-15A.

I need to be able to measure, with 1% or better accuracy, the total energy
dissipated in the load over the duration of the experimental run.

I don't need instantaneous V or I values - all I need to know is the total
energy consumption over the run.

The only sensible way I can think of doing this is to use a data logger,
and sample V and I at a high rate thoughout the experimental run, then
calculate average power over the run, then multiply by run time.

However, this seems like a very round-about way of achieving my goal.
Anyone have any thoughts on other ways of doing this? I must stress that
it is the electrical energy input to the system that I'm interested in, so
measuring temperature rise of the load etc. is out of the question.


you need a digital data logger connected to a PC. eg Maplin sell
multimeters with RS232 output which give a serial data o/p. so if the load
has no phase problems you just need to measure the current. I don't have
detailed knowledge of the specs.
http://www.maplin.co.uk/Module.aspx?... ID=&doy=20m2
A serial software interface program like ProCom or VisualBasic Studio is
also needed to sample the readings in the PC. Or GPS navigation software
for NMEA might do the same sampling job at a pinch.