Measuring Range Rng; Measuring Speed Spd; Triggering Trig; Delay - Hameg HM8118 Manual

S e t t i n g o f i n s t r u m e n t p a r a m e t e r s
The error message „DCR too high" indicates that
the resistive load of the connected DUT (device
unter test) is too high for the selected BIAS current.
In this case the BIAS current can't be activated.
Unipolar capacitors must be connected with correct
polarity, i.e. the positive terminal must be con-
nected to the left contact and the negative terminal
to the right contact. The BIAS voltage (BIAS) is only
available for capacitance measurements.
Inductors must be discharged before disconnecting!
This means that after switching off of the BIAS current
a waiting period is necessary so the current may
decay to zero. The waiting period is indicated in the
display by „Please wait...". The BIAS current (BIAS) is
only available for inductance measurements.

5.1.4 Measuring range RNG:

The ranges may be selected automatically or manually from
3 Ω to 500 kΩ.

5.1.5 Measuring speed SPD:

The LCR bridge HM8118 offers 3 measurement speeds:
– SLOW (slow),
– MED (medium) or
– FAST (fast).
The number of measurements with continuous triggering are
1.5 per second in SLOW, 8 per second in MED or 14 per second
in FAST.
This adjustment is a compromise between measurement accu-
racy and speed. Slow measurement speed tends to an accurate
measurement, while fast measurement leads to a less accurate
measurement. At very low measuring frequencies the speed is
automatically reduced. For measuring speed selection press
the SELECT button 3 , access the menu SETUP and choose
the setting SPD.

5.1.6 Triggering TRIG:

At this point the trigger source and the trigger mode can be
selected. Following trigger modes and sources are possible:
– CONT (continuous trigger): At the end of each measurement
a new measurement will be automatically performed.
– MAN (manual trigger): A measurement will be triggered by
pressing the TRIG/UNIT button
– EXT (external trigger): A rising slope at the external trig-
ger input will perform a measurement. Any signals at this
input will be ignored until the measurement cycle has been
completed. The TRIG/UNIT button
surement was started. Each trigger will only generate one
measurement.

5.1.7 DELAY:

A trigger delay may be selected from 0 to 40,000 ms (40 s).

5.1.8 Average (AVG):

If the function AVG is selected the average of a number of mea-
surements will be calculated and displayed. For the selection
of the number of measurements press the SELECT button
3
, use the menu SETUP and choose AVG. The number may
be chosen from 2 to 99 or MED (medium). MED (medium) is a
medium calculation mode. The display will show „AVG", if this
function is active. If MED is selected, the HM8118 will perform
6 measurements. It will discard the smallest and the highest
44
Subject to change without notice
27 .
27 will light up, if a mea-
and average the remaining 4 results. This method is handy for
eliminating single erroneous results.
If e.g. a component is inserted into a test fixture, the first mea-
surement will in general be wrong because contact is made
during a measurement cycle, so this first result will differ
substantially from the following ones. So this first wrong re-
sult will be discarded to avoid displaying wrong measurement
values based on measuring transient effects. Averaging may
also be used with manual or external triggering. The number
of measurements per active trigger will then be determined by
the number of averaging periods.
5.1.9 Display of test signal levels V
At this point the display of the voltage as well as the current at
the component's terminals may be turned on/off.

5.1.10 Guarding GUARD:

For guarded measurements two modes are available: AUTO
(automatic) or DRIVE (controlled). Guarding is used at low
voltage levels.
If the GUARD function is selected the outer BNC contacts
20 23
... will be connected to an internal generator which feeds
them with a replica of the measuring voltage thus eliminating
within certain limits the capacitance of the cables connected
which would cause erroneous capacitance measurements.
The GUARD function should be activated when a test
fixture with high capacitance is used (i.e. HZ184)
and the impedance of the DUT (device under test) is
higher than 25 kΩ at frequencies above 100 kHz.
– OFF: Guarding off; the outer contacts of the BNC connectors
are connected to ground potential.
– DRIVE (controlled): the outer BNC contacts are connected
to the internal guard voltage generator with LOW DRIVE
potential.
– AUTO (automatic): As long as the measurement range is 1
to 4 or the frequency is below 100 kHz, the outer BNC con-
nectors are connected to ground potential. If the measure-
ment range is 5 or 6 or the frequency is beyond 100 kHz, the
outer BNC connectors are connected to an active protective
voltage source (for potential control).

5.1.11 Deviation DEV_M:

The display of the percentage
of the measured main value from the reference value REF_M
can be turned on/off here.

5.1.12 Reference REF_M:

At this point a measured value may be entered as the reference
into the main (M) reference memory. The following units are
allowed: H, mH, µH, nH, F, mF, µF, nF, pF, Ω, mΩ
S, kS, mS, µS, nS, pS. As long as this field is open, the actual
measured value of the DUT (= Device Under Test) may be defined
as reference by pressing the

5.1.13 Deviation DEV_S:

The display of the percentage
of the measured second value (Sub) from the reference value
REF_S can be turned on/off here.

5.1.14 Reference REF_S:

The measured value of the loss factor or the quality factor Q can
be entered into the reference memory S. The following units
, , ,
are allowed: Ω, mΩ kΩ MΩ S, kS, mS, µS, nS, pS or °. As long
(voltage) / I (current):
m m
Δ % or Δ ABS (absolute deviation)
, ,
kΩ MΩ
TRIG button.
Δ % or Δ ABS (absolute deviation)
,
or