Zero Adjustment; Measuring Accuracy - Hameg Instruments HM8018 Handbuch

or kΩ according to the selected measurement
range. It is possible to perform measurements
between 10 mΩ and 200 kΩ.
Kelvin Input (5-pin diode jack)
Input for connection of the HZ18 four-wire test
cable.
L(pushbutton)
Selection of the „inductance measurement"
mode
This mode permits to measure inductance values
between 0,1µH and 200H. The reading is in CIH/
mH/H according to the range selected with (12).
Probe Compensation (R trimmer)
Trimmer to be adjusted with a screwdriver for
compensation of the cable capacitance when
using the HZ18 cable.
/ Low/High(4mm banana jacks)
Terminals for connection of the test object. This
input is not influenced by the setting of (5).
C (pushbutton)
Selection of the „Capacitance measurement"
mode This mode permits to measure capacitance
values between 0.1pF and 200µF. The reading is
in pF, nF or µF according to the range selected
with (12).
G (pushbutton)
Selection of the „Parallel conductance" mode
This mode permits to measure the parallel con-
ductance of capacitors. The reading is in µS or
mS according to the range selected with (12). It
is possible to perform measurements between
0.1µS and 200mS.
Display Zero (R trimmer)
Trimmer to be adjusted with a screwdriver for
zero correction of the display.
2V DC (pushbutton)
Connection of a 2V DC voltage to the connecting
terminals 6/8. This procedure is recommended
for measurement of poled capacitors to avoid
pole reversal of the capacitor by the AC test
voltage. The activation of this mode is displayed
by the „DC" LED.
Range (knob)
7-position range selection knob for selection of
the different measurement ranges (±15digit).
Selection of the test function
The desired test function is selected via the
function selection buttons (2)/(4)/(7) and (9). The
dimensions allocated to the corresponding test
functions are indicated in the display. Beside L
and C measurement, functions for determination
of the senes resistance values of inductor coils
Sous réserve de modifications / Reservado el derecho de modificación
and parallel conductance values of capacitors are
available. Measurement of these values with
these additional functions permits to calculate
quality and loss factor of the tested component.
The corresponding formulas are specified in the
chapeter entitled „Dissipation Factor and 0-
factor". After selecting the measurement
function, the range selection knob (12) is used to
adjust the corresponding measurement range.
The appropriate dimension is indicated in the
display.
Connection of the test object
The components under test can be connected in
two different ways to the HM8018 unit. Two 4mm
banana jacks are available for quick and rough
measurements. The test object is either plugged
in or fixed below the screw-type terminals. Under
different conditions, this fast procedure is not
sufficiently precise (please referto the chapter
entitled „Dissipation Factor and 0-factor" for furt-
her information). In case of measurements
requiring higher accuracy, the HZ18 Kelvin probe
offered in the HAMEG accessory line should be
used.

Zero adjustment

Normally the HM8018 unit is zero-adjusted.
However. the display may indicate some digits
due to aging or varying environment temperatures,
even when no test object is con nected. Th is d
isplay e rror ca n be el i m i nated with the „Dis-
play Zero" trimmer in all measurement ranges.
When using the Kelvin input and the HZ 18 test
lead, the lower measurement ranges can be
adapted to the used cable with the „Probe
Compensation" trimmer. This has no influence
upon the adjustement perfor med with the „Dis-
play Zero" trimmer.

Measuring accuracy

The HM8018 unit offers a basic of 0.5% of
reading. To make full use of this measuring
accuracy, the components under test should be
very carefully connected. Basically, care has to
be taken of good contact making and the
connecting wires between the terminals and the
component to be measured should be as short
as possible. To increase measuring accuracy and
reliability of the test resu Its, the HM8018 unit
has three different test frequencies. These are
automatically switched over via the range selector
for better practical handling. The test frequencies
are 160Hz in the highest measuring ranges,
1600Hz in the 20nF/20mH and 200nF/200mH
ranges and 16kHz in the lowest range. In case of
losses in the test leads due to comparably high
test currents - which occur especially in case of
low inductance and high capacitance - the HZ18
Kelvin cable is recommendable. Its influence upon
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