What do you use to measure panel amps?

[BilljustBill]

I have a lightduty multimeter. It has a way to measure up to 20 amps, but it is very limited for lengths of time while checking amps. No more than a few seconds of measuring and must allow it to cool for 15 minutes.

What do you use to load and measure panel amps?

Thanks,
Bill

[greenHouse]

Bill,

I have a Fluke 289. It won't read over 10 amps, but for more than that, I use a shunt and the millivolt setting.

I have a client (my company does monitoring hardware and software =and= consulting) who has "suggested" that I drop $175 on the AC/DC clamp on accessory for the 289. As soon as I can extract some money from them (heh) I'll pick up that clamp on and leave the days of using shunts behind

[mountain]

No need to use any sort of expensive current sensor.

For a medium size panel (1-50W) Insert a 0.01 ohm in series with the +ve side as a current measuring shunt. Use a standard multimeter on DC mV to measure the voltage drop across the shunt.

ohm's law tells us that you will measure 10 mV per Amp produced

the power dissipated by the 0.01 ohm shunt would be very minimal, (P=I^2xR), ie at 1 Amp, the power dissipated would be 0.01W.

For a larger panel, (>50W) use a 0.001 ohm shunt (1mV/A)
For a small panel (<1 W) use a 0.1 ohm shunt (100 mV/A

Current measuring shunts are very cheap and easy to get.

http://www.alliedelec.com/search/productdetail.aspx?SKU=2964283

[hay4man]

http://www.rc-electronics-usa.com/ammeters/dc-amp-meter.html

or if you like recording serial data:

http://ebikes.ca/drainbrain.shtml