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DMM with Kelvin (4-wire) small resistance measurement / English
2. OPERATING PRINCIPLE
Suppose we wished to measure the resistance of some component located a significant
distance away from our ohmmeter. Such a scenario would be problematic, because an
ohmmeter measures all resistance in the circuit loop, which includes the resistance of the
wires (R
) connecting the ohmmeter to the component being measured (R
wire
Usually, wire resistance is very small (only a few ohms per hundreds of feet, depending
primarily on the gauge (size) of the wire), but if the connecting wires are very long, and/or
the component to be measured has a very low resistance anyway, the measurement error
introduced by wire resistance will be substantial.
An ingenious method of measuring the subject resistance in a situation like this involves the
use of both an ammeter and a voltmeter. We know from Ohm's Law that resistance is equal
to voltage divided by current (R = E/I). Thus, we should be able to determine the resistance
of the subject component if we measure the current going through it and the voltage dropped
across it:
Current is the same at all points in the circuit, because it is a series loop. Because we're only
measuring voltage dropped across the subject resistance (and not the wires' resistances),
though, the calculated resistance is indicative of the subject component's
resistance (Rsubject) alone.
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3. FEATURES
Low resistance range
Display
):
subject
Maximum output current 200mA (400mΩ)
Sampling Rate
relative measurement
Over Range Indicator
Low Battery Indication
Auto Power Off
Operating Temperature
Storage Temperature
Power source
Dimensions
Weight
Accessories
DMM with Kelvin (4-wire) small resistance measurement / English
0~40Ω
Large LCD with bar graph display
2 times per second.
OL of highest digit is displayed.
The
is displayed when the battery Voltage drop below the
operating voltage.
To conserve battery life, the meter will automatically turn off
after approx. 30 minutes of non-use. When this happens, the
state of the meter is saved. In order to disable auto power off
function, power on the meter when any of the push function ,
except for HOLD, is pressed down.The "APO" sign on the LCD
panel indicates whether the auto power-off function is enabled
or not.
0ºC to 40ºC (32ºF to 104ºF) and Humidity below 80% RH
-10ºC to 60ºC (14ºF to 140ºF) and Humidity below 70% RH
6x1.5V Size "AA" battery or Equivalent (DC9V)
200(L) x 92(W) x 50(H) mm
Approx 700g include battery
4 sets Test kits, 4pcs iron rods, 6pcs battery, Carrying
case, manual
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