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To compensate for the line resistance of measurement cables,
it is necessary to short circuit the measurement cables and
press the NULL
key. This triggers the offset correction of
the entire measurement section. This value will be shown next
to the soft menu key NULL and on the display below the main
measurement value. The line resistance of the measurement
cable, contact resistances and thermoelectric voltages between
different metals have been intentionally eliminated by this offset
correction. The compensation values will not be stored after the
HMC8012 has been switched off and have to be redetermined.
In addition, you may also enter the NULL value numerically or
via knob.
The soft menu key ADC
Rate and the knob allow you to
set the display refresh rate to Slow (5 measurements per
second), Medium (10 measurements per second) or Fast
(200 measurements per second).
The maximum accuracy in measurements is achie-
ved when using the setting „Slow (ADC rate).
You can select the option Slow, Medium or Fast via soft
menu key AC Filter (main function AC I) and knob. This
applies to a low pass filter. A lower setting (Slow) ensures
more stable measurement values. However, the measurement
is slow and signal elements of higher frequency will be atte-
nuated. Depending on the input frequency, this function will
smoothen the displayed value. The setting Medium is saved
as default value. Select the setting Slow for an input frequency
of
50kHz, and select Fast for a setting of
<
If the second function (2nd Function) is activated (dB or dBm),
you have the option to define a reference value. For the function
dB, the reference value is the current (Ref. Value). You can
set the reference value numerically or via knob. If a reference
value is defined, you can reset the previously selected reference
value via soft menu key „Null.
For the function dBm, the reference value is 1mW and is
often used for RF signal measurements. If the dBm function
is activated, the multimeter performs a measurement and
calculates the power supplied to a comparator resistance. The
reference value (Ref. Value) in this case is 50, 75 or 600
Ω. In addition, you can set a user-defined value (User) either
numerically or via knob.
7
DC V
4
DC I
5.3
1
SENSOR
The frequency display can be added in the main function AC V
and AC I as the second measurement function (2nd).
0
HOLD
F10H250V
Fig. 5.3: measuring frequency
The measurement time can be set via soft menu key
Gate Time. The measurement time can vary between 10ms,
100ms and 1s and is shown below the frequency information on
the display. The display refresh rate is dependent on the selected
ADC rate in the AC V or AC I mode. For the setting „Slow,
the measurement rate of the frequency measurement is 1
measurement per second, for „Medium it is 10 measurements
1kHz.
per second and for „Fast it is 100 measurements per second.
>
5.4
For the resistance measurement, connect measurement cables
with clamps to the respective connectors on the front panel of
the instrument. A 2-wire measurement only requires the COM
and V connectors. A 4-wire measurement also requires the LO/
HI connectors (SENSE). After connecting the cables and connec-
ting with a resistance, press the Ω key. The resistance value
will show on the display. During a resistance measurement,
7
the cable resistance (cable offset) requires particular attention.
DC V
Especially for small resistances which may be close to the cable
4
offset it is recommended to zero the measurement section.
DC I
1
A zero measurement is also called a relative measurement,
SENSOR
i.e. each measurement value indicates the difference between
a saved zero value and the input signal.
0
HOLD
F10H250V
Fig. 5.4: measuring resistance (2-wire)
8
9
I n s t r u m e n t F u n c t i o n s
AC V
SETUP
5
6
ESC
SAVE
AC I
CAP
measuring Frequency
RECALL
2
3
ENTER
MEAS
HELP
.
--
NULL
TRIG
SHIFT
SENSE
4 W
max. 200 V
Fused
pk
+
frequency
measuring resistance
8
9
AC V
SETUP
5
6
ESC
SAVE
AC I
CAP
RECALL
2
3
ENTER
MEAS
HELP
.
--
NULL
TRIG
SHIFT
SENSE
4 W
max. 200 V
Fused
pk
Subject to change without notice
CAT II
600 V
max.
max.
600 V
1000 V
pk
pk
max.
10 A
max. 1000 V
pk
-
source
CAT II
600 V
max.
max.
600 V
1000 V
pk
pk
max.
10 A
max. 1000 V
pk
-
+
resistance 2-wire
(Ω)
39
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