Re: multimeters rms v avg. reading for res power systems
Agree totally with iwire.
Many years ago, I was out on a service call to a church kitchen, their mixer wouldn't work and they said the outlet was dead. I had my simpson 260, stuck the probes in the outlet, and presto, 120 volts. I told the lady that the outlet was good, the mixer must be broken. She said "no, the mixer still works if I plug it in over there."
Hmmmmm.... I go out to the truck and get a drill motor, plug it into the outlet in question, it doesn't work. But Simpson still says 120 volts.
I take the plug out... the box is filled with moisture and dead roaches, and the screw terminal connections are all gunky and green and corroded.
There was enough resistance in the connnections that under load, there was a severe voltage drop and the appliances wouldn't run, but with the Simpson's extremely high impedance, it was reading just about full voltage when not under load. Remember, in series, the largest impedance will drop the majority of the voltage.
I also worked occasionally in a place that pumped brine out of a salt dome and then evaporated the water out for making table salt. Everything in the place was wet and damp and salty. Talk about making a digital meter go nuts! (BTW, they used an ungrounded 480 delta for their equipment)
For typical troubleshooting of everyday problems, give me my Wiggy!
[ February 10, 2005, 03:47 PM: Message edited by: crossman ]