52
Subject to change without notice
c o n t r o l e l e m e n t s a n d d i s p l a y
10 control elements and displays
10.1 general functions
1
Display
16 digit display for displaying measurement results, menu
selection and menu items.
2
PoWer
Button for activating standby-function. The controls and the
display are turned off. The instrument itself stays turned on
as long as it is connected to the supply voltage. This has the
advantage that the instrument is immediately functional after
turn-on. Also the reference voltage source will remain ener-
gized, so any drift after turn-on will be eliminated, also its long
term drift will be substantially improved.
To switch-off the instrument completely, the line switch on the
back panel has to be operated.
3
HolD
“Freezing“ of the displayed measured value.
By pressing one of the function selection buttons
6
to
15
or
MENU
18
the HOLD function is left.
4
Zero
Zero for DC voltage, DC current, 4-wire-resistance and 2-wire-
resistance measurements. The ZERO function is not provided
for AC voltage and AC current measurements. Both cables
have to be shorted and the ZERO button has to be pressed.
This results in elimination of the resistances of the measure-
ment cables, resistances and thermal voltages at the junction
of different metals.
Compensation values remain, even after turn-off the instru-
ment. They have to be redetermined if necessary.
the Zero button is deactivated in the measuring
functions
δ
Pt for Pt sensors or
δ
tH for thermo-
couples.
Zero adjustment with temperature measurement
1. With regard to the type of temperature sensor one the fol-
lowing measurement ranges must be chosen:
PT100
Ω 2 wire / Ω 4 wire
1 kΩ range
PT1000
Ω 2 wire / Ω 4 wire
10 kΩ range
Thermocouple V
DC
100 mV range
Whether 2-wire- or 4-wire-measurement has to be selected
depends on the PT temperature sensor used.
2. Short the temperature sensor.
3. The ZERO button
4
is to be pressed to compensate for
influences within the measurement circuit.
4. After compensation jump to the adequate temperature
measurement function by pressing ZERO
4
some measurement instruments offer an „auto-
matic zero function“. this function regularly inter-
rupts the measurement and shorts the input. then
a partial 0-adjustment is made.
the Hm8112-3 has no Auto Zero function, becau-
se the zero adjustment of the complete measure-
ment circuit is very important.
5
locAl
By sending a command via interface to the HM8112-3 the instru-
ment is set to the remote mode. Remote control is switched off
by pressing button LOCAL. The instrument returns to manual
mode and can be operated from the front panel.
10.2 Buttons for the various measurement functions
If the measurement function is changed, the HM8112-3 assumes
the sampling rate selected, unless a sampling rate between 10 s
and 60 s is chosen. Then changing the measuring function will
set the sampling rate automatically to 1 s.
The buttons offering more functions are illuminated. Natu-
rally, other measuring functions can be called up by pressing
unlighted buttons.
The terminals are illuminated, too, and indicate the terminals
to be used with the corresponding functions.
Voltage measurement
6
V
Dc
V
A
SENSE
SOURCE
LO
HI
max.
250Vrms
max.
850
Vpk
max.
850
Vpk
Ω
,
ϑ
FUSE
1A
F250V
CAT
II
max. INPUT
600Vrms / 1Arms
+
–
Direct or
alternating voltage
9
Änderungen vorbehalten
W i c h t i g e H i n w e i s e
B e z e i c h n u n g d e r B e d i e n e l e m e n t e
2 Bezeichnung der Bedienelemente
1
DisPlAy
– 16-stelliges Display
2
PoWer
– Stand-By / EIN
3
HolD DisPlAy
– angezeigter Wert im Diplay speichern
4
Zero
– Nullabgleich der Messstrecke
5
rm/locAl-taste
–
Fernbedienung über Interface ausschalten
6
V
Dc
– Gleichspannungs-Messung
7
A
Dc
– Gleichstrom-Messung
8
V
Ac
– Wechselspannungs-Messung mit AC-Kopplung
9
A
Ac
– Wechselstrom-Messung
10
V
Ac+Dc
– Wechselspannungs-Messung mit DC-Kopplung
11
Ω
– Widerstandsmessung, 2- und 4-Draht
12
FreQ./PerioD
– Frequenz und Periodendauer mit V
AC
13
δ
Pt
- Temperaturmessung mit PT-Messfühler,
2- und 4-Draht
14
- Dioden- / Durchgangsprüfung
15
δ
tH
– Temperaturmessung mit Thermoelement, 2-Draht
16
mAX
– maximaler Messwert während einer Messreihe
17
min
– minimaler Messwert während einer Messreihe
18
menu
– Auswahl Menüsystem, Übernahme von Menüpunkt
/ Parameter
19
esc
– Verlassen des Menüsystems ohne Werte zu überneh-
men
20
– Abwärts: Messbereichstaste und Scrollfunktion im
Menü
21
Auto
– Umschalten manuelle / automatische Messbe-
reichswahl
22
enter
– Sonderfunktion: Auswahl der Parameter im
Logger-Menü
23
– Aufwärts: Messbereichstaste und Scrollfunktion im
Menü
24
V sense
– Eingang für Spannungs-, Frequenz-, Wider-
stands-, Temperaturmessung
25
lo
– Bezugsmasse für Messung
26
A source
– Eingang für Strommessung
27
Fuse
– Messkreissicherung 1 A / 250 V (superflink)
geräterückseite
28
Kaltgeräteeinbaustecker
mit Netzschalter
29
usB/rs-232 schnittstelle
Option: HO880 IEEE-488 (GPIB), eingebauter Messstellen-
umschalter im HM8112-3S
30
netzspannungswahlschalter
(115 V bzw. 230 V)
1
2
27
3 4 5
6
7
8
9
10 11 12 13 14 15
16 17
19 20 18 21 22 23
24
25
26
29
28
30
