Abd ul-Rahman Lomax <[email protected] <mailto:[email protected]>>
wrote:
First of all, the clamp-on probes used with the PCE-830 cannot
measure DC current
I don't know about this one, but my 30-year-old analog Radio Shack
clip-on ammeter sure can measure DC. You turn the knob to DC and it
works fine.
They operate through sensing the changing magnetic fields from
changing current in the wires. DC, no change.
My point is that as long as it reverses it is AC and will be detected.
Adding DC voltage just adds a bias. It does not make the AC go away.
Unless, as noted, you add so much that it stays positive.
Secondly, the PCE meter not being designed to measure DC power -- no
DC current sensors -- . . .
If it cannot read a DC bias it is useless. I am sure it can. They all
could 40 years ago.
(You are assuming a single solid-state "switch" in the control box,
so that AC and DC turn on and off together. But the AC and DC could
be isolated, separated, essentially a DC bypass.)
It is one wire. How do you keep them separated?!?
This makes the second such failure to understand test equipment on
the part of Essen. The first was the humidity meter. Did you ever
understand that one?
Sure. I looked at the manual and contacted the manufacturer, and they
said that meter with that probe works fine for that purpose. It says it
measures the enthalpy of steam. I don't know why you think it doesn't
when the manual and brochure clearly state that it does.
I admit, I tend to take for granted whatever the manufacturers' say. If
they say "this meter measures the enthalpy of steam" (the wetness) I
assume they are right. The PCE company would not stay in business long
if any high school kid could find a way to fool their meters, or if the
meter indicated a wire is dead when it is alive.
Recently, Shanahan said that IR cameras do not measure temperatures
correctly. He gave a long list of theoretical reasons. I pointed out
that the manufacturer sells these things to measure temperature, and
millions of engineers use them for that purpose, plus Levi compared this
one to a thermocouple, so I am sure Shanahan is wrong.
- Jed
