Hameg HM8112-3 User manual

6½-DIGIT
PRECISION-MULTIMETER
HM8112-3
Handbuch / Manual
Deutsch / English
99 Washington Street
Melrose, MA 02176
Fax [phone]
TestEquipmentDepot.com

32 Subject to change without notice
General remarks regarding the CE marking
HAMEG measuring instruments comply with the EMI norms. Our tests for
conformity are based upon the relevant norms. Whenever different maximum
limits are optional HAMEG will select the most stringent ones. As regards
emissions class 1B limits for small business will be applied. As regards
susceptability the limits for industrial environments will be applied.
All connecting cables will influence emissions as well as susceptability
considerably. The cables used will differ substantially depending on the
application. During practical operation the following guidelines should be
absolutely observed in order to minimize EMI:
1. Data connections
Measuring instruments may only be connected to external associated
equipment (printers, computers etc.) by using well shielded cables. Unless
shorter lengths are prescribed a maximum length of 3 m must not be exceeded
for all data interconnections (input, output, signals, control). In case an
instrument interface would allow connecting several cables only one may be
connected.
In general, data connections should be made using double-shielded cables.
For IEEE bus connections the double-shielded HAMEG cables HZ72S and HZ72L
are suitable.
2. Signal connections
In general, all connections between a measuring instrument and the device
under test should be made as short as possible. Unless a shorter length is
prescribed a maximum length of 3 m must not be exceeded, also, such
connections must not leave the premises.
All signal connections must be shielded (e.g. coax such as RG58/U). With signal
generators double-shielded cables are mandatory. It is especially important
to establish good ground connections.
3. External influences
In the vicinity of strong magnetic or/and electric fields even a careful measuring
set-up may not be sufficient to guard against the intrusion of undesired signals.
This will not cause destruction or malfunction of HAMEG instruments, however,
small deviations from the guranteed specifications may occur under such
conditions.
HAMEG GmbH
Die HAMEG GmbH bescheinigt die Konformität für das Produkt
The HAMEG GmbH herewith declares conformity of the product
HAMEG GmbH déclare la conformite du produit
Bezeichnung / Product name / Designation:
Präzisions-Multimeter
Precision-Multimeter
Multimétre de précision
Typ / Type / Type: HM8112-3
mit / with / avec: –
Optionen / Options / Options: –
mit den folgenden Bestimmungen / with applicable regulations / avec les
directives suivantes
EMV Richtlinie 89/336/EWG ergänzt durch 91/263/EWG, 92/31/EWG
EMC Directive 89/336/EEC amended by 91/263/EWG, 92/31/EEC
Directive EMC 89/336/CEE amendée par 91/263/EWG, 92/31/CEE
Niederspannungsrichtlinie 73/23/EWG ergänzt durch 93/68/EWG
Low-Voltage Equipment Directive 73/23/EEC amended by 93/68/EEC
Directive des equipements basse tension 73/23/CEE amendée par 93/68/CEE
Angewendete harmonisierte Normen / Harmonized standards applied /
Normes harmonisées utilisées
Sicherheit / Safety / Sécurité
EN 61010-1:2001 (IEC 61010-1:2001)
Hersteller HAMEG GmbH KONFORMITÄTSERKLÄRUNG
Manufacturer Industriestraße 6 DECLARATION OF CONFORMITY
Fabricant D-63533 Mainhausen DECLARATION DE CONFORMITE
Überspannungskategorie / Overvoltage category / Catégorie de surtension: II
Verschmutzungsgrad / Degree of pollution / Degré de pollution: 2
Elektromagnetische Verträglichkeit / Electromagnetic compatibility /
Compatibilité électromagnétique
EN 61326-1/A1 Störaussendung / Radiation / Emission:
Tabelle / table / tableau 4; Klasse / Class / Classe B.
Störfestigkeit / Immunity / Imunitee: Tabelle / table / tableau A1.
EN 61000-3-2/A14 Oberschwingungsströme / Harmonic current emissions /
Émissions de courant harmonique:
Klasse / Class / Classe D.
EN 61000-3-3 Spannungsschwankungen u. Flicker / Voltage fluctuations and
flicker / Fluctuations de tension et du flicker.
Datum /Date /Date
01.12.2004
Unterschrift / Signature /Signatur
G. Hübenett
Produktmanager

33
Subject to change without notice
Content
Deutsch 3
English 32
Decleration of Conformity 32
General remarks regarding the CE marking 32
6½-Digit Precision-Multimeter HM8112-3 35
Specifications 35
Important hints 36
Symbols 36
Unpacking 36
Positioning 36
Transport 36
Storage 36
Safety instructions 36
CAT II 36
Proper operating conditions 37
Warranty and Repair 37
Maintenance 37
Protective Switch Off 37
Power supply 37
Line fuse 37
Power switch 37
Control-Elements 38
Concept of the HM8112-3 39
Reference 39
Integrated AD converters 39
Moving average 39
Measurement of alternating values 39
Introduction to the operation of the HM8112-3 39
Factory settings 39
Control elements and displays 40
Buttons for the various measurement functions 40
Continuity test 42
Max / Min values 42
Range selection 42
Menu structure 43
Menu prompting 44
Menu structure and function 45
Measurement inputs 46
Serial Interface 47
Data communication 47
Layout of commands 47
Listing of commands 48

34 Subject to change without notice
HM8112-3
6½-Digit Precision-Multimeter
HM8112-3
6½-digit LCD-display (1.200.000 points)
True rms measurements of AC+DC or AC
2-wire- / 4-wire measurements
Resolutions 100 nV, 100 pA, 100 µΩ, 0,01 °C / °F
Offset correction
Range selection automatically and manual
10 measurements per second
Measuring time 0,1 sec to 60 sec
Input impedance >1GΩ(0,1 V and 1VDC ranges)
RS-232 Interface (Option: USB, IEEE-488)
HZ42 19’’-rackmont-kit
Precise temperature
measurement with sensor
HZ887
˚C
˚F
RS-232

35
Subject to change without notice
Specifications
6½-Digit Precision-Multimeter HM8112-3
SPECIFICATIONS
Valid at 23 degrees °C after a 30 minute warm-up period
Included in delivery:
Multimeter HM8112-3, line cord, manual, HZ15 measuring cables
Accessories optional:
HZ887: Temperataure sensor (PT100; -50°C...+400°C )
HZ42:19" Rackmount-kit 2RU for frame height 75mm
DC Specifications
Ranges: 0.1 V; 1 V; 10 V; 100 V; 600 V
Input impedance:
0.1 V; 1.0 V >1 GΩ
10 V; 100 V; 600 V 10 MΩ
Accuracy: Values given are in ±(% of reading + % of full scale)
1 year; 23 ±2 °C Temperature coefficient
Range % rdg. + % f.s. 10...21 °C + 25...40 °C
0.1 V 0.005 + 0.0006 0.0008
1.0 V 0.003 + 0.0006 0.0008
10.0 V 0.003 + 0.0006 0.0008
100.0 V 0.003 + 0.0006 0.0008
600.0 V 0.004 + 0.0006 0.0008
Integration time: 0.1 sec 1 to 60 sec
Display range: 120,000 digit 1,200,000 digit
600 V range: 600,00 digit 600,000 digit
Resolution: 1 µV 100 nV
Zero point
Temperature coefficient: ≤0,3 µV/°C
Long term stability: ≤3 µV for 90 days
AC specifications
Ranges: 0.1 V; 1 V; 10 V; 100 V; 600 V
Measuring method: true rms DC or AC coupled
(except 0.1 V range)
Input impedance:
0.1 V: 1 GΩII <60 pF
1 V to 600 V: 10 MΩII <60 pF
Response time: 1.5 sec to within 0,1% of rdg.
Accuracy: For sine wave signals >5% of range.
Values given are in ±(% rdg. +% f.s.);23 ±2 °C for 1 year
Range 20 Hz – 1 kHz – 10 kHz – 50 kHz – 100 kHz –
1 kHz 10 kHz 50 kHz 100 kHz 300 kHz
0.1 V 0.10 +0.08 5+0.5 (5 kHz)
1.0 V 0.08 +0.08 0.15+0.08 0.3+0.1 0.8+0.15 7+0.15
10.0 V 0.08 +0.08 0.10+0.08 0.3+0.1 0.8+0.15 4+0.15
100.0 V 0.08 +0.08 0.10+0.08 0.3+0.1 0.8+0.15
600.0 V 0.08 +0.08 0.10+0.08
Temperature coefficient 10...21°C and 25...40°C; (%rdg. + %f.s.)
at 20 Hz - 10 kHz: 0.01 + 0.008
at 10 kHz - 100 kHz: 0.08 + 0.01
Crest factor: 7:1 (max. 5 x range)
Integration time: 0.1 sec 1 to 60 sec
Display range: 120,000 digit 1,200,000 digit
600 V range: 60,000 digit 600,000 digit
Resolution: 1 µV 100 nV
Overload protection:
(V-HI to V- LO) and to chassis:
Measurement ranges: all
all the time 850 Vpeak or 600 VDC
Maximum input voltage LOW against
chassis/safety earth: 250 Vrms at max. 60 Hz or 250 VDC
Current specifications
Ranges: 100 µA; 1 mA; 10 mA; 100 mA; 1 A
Integration time: 0.1 sec 1 to 60 sec
Display ranges: 120,000 digit 1,200,000 digit
1 A range: 100,000 digit 1,000,000 digit
Resolution: 1 nA 100 pA
Accuracy: DC 45 Hz–1 kHz 1 kHz–5 kHz
(1 year; 23 ±2 °C) 0.02+0.002 0.1+0.08 0.2+0.08
Temperature coefficient: 10...21 °C 25...40 °C
(% rdg. + % f.s.): 0.002+0.001 0.01+0.01
Voltage: <600 mV to 1,5 V
Response time: 1.5 sec to within 0.1% of rdg.
Crest factor: 7:1 (max. 5 x range)
Overload protection: Fuse FF 1 A 250 V
Resistance specifications
Ranges: 100Ω, 1kΩ, 10kΩ, 100kΩ, 1MΩ, 10MΩ
Integration time: 0.1 sec 1 to 60 sec
Display ranges: 120,000 digit 1,200,000 digit
Resolution: 1mΩ100 µΩ
Accuracy: Values given are in ±(% rdg. + % f.s.)
1 year; 23 ±2°C Temperature coefficient/°C
Range %rdg. + %f.s. 10...21 °C and 25...40 °C
100 Ω0.005 + 0.0015 0.0008
1 kΩ0.005 + 0.001 0.0008
10 kΩ0.005 + 0.001 0.0008
100 kΩ0.005 + 0.001 0.0008
1 MΩ0.05 + 0.002 0.002
10 MΩ0.5 + 0.02 0.01
Measuring current: Range Current
100 Ω, 1kΩ1 mA
10 kΩ100 µA
100 kΩ10 µA
1 MΩ1 µA
10 MΩ100 nA
max. measuring voltage: approx. 3 V
Overload protection: 250 Vpeak
Temperature measurement specifications
PT100 / PT1000 (EN60751) 2- or 4-wire measurements
Range: –200 °C to +800 °C
Resolution: 0.01 °C; measuring current 1mA
Accuracy: ±(0.05 °C + tolerance of sensor +0.08 K)
Temperature coefficient
(10...21 °C + 25...40°C: <0.0018 °C/°C
NiCr-Ni (K-Type)
Range: –270 °C to +1372 °C
Resolution: 0.1 °C
Accuracy: ±(0.7% rdg. +0.3 K)
Fe-CuNi (J-Type)
Range: –210 °C to +1200 °C
Resolution: 0.1 °C
Accuracy: ±(0.7% rdg. +0.3 K)
Frequency and period specifications
Range: 1 Hz to 100 kHz
Resolution: 0.00001 Hz to 1 Hz
Accuracy: 0.05% (rdg.)
Measuring time: 1 to 2 sec
RS-232 Interface
RS-232 standard: 9600 or 19200 Baud
Functions: Control / Data fetch
Inputs: Function, range, integration time, start
command
Outputs: Measurement results, function, range,
integration time (10 ms to 60 s)
Miscellaneous
Time to change range or function:
approx. 125 ms with DC voltage, DC current, resistance
approx. 1 sec with AC voltage, AC current
Memory: 30.000 readings / 128 kB
Protective class: I, EN 61010 (IEC 1010)
Power supply: 105–254 V; 50/60 Hz
Power consumption: approx. 8 W
Operating temperature: +10 °C....+40 °C
Storage temperature: –40 °C....+70 °C
Humidity: <75 %, no condensation
Size (W x H x D): 285 x 75 x 365 mm
Weight: approx. 3 kg
Optionen: USB- bzw. IEEE-Schnittstelle
Subject to change without notice
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FAX [phone] - TestEquipmentDepot.com

36 Subject to change without notice
picture 3
picture 2
picture 1
Important hints
(1) (2) (3) (4) (5) (6)
Symbols
Symbol 1: Attention, please consult manual
Symbol 2: Danger! High voltage!
Symbol 3: Ground connection
Symbol 4: Important note
Symbol 5: Hints for application
Symbol 6: Stop! Possible instrument damage!
Unpacking
Please check for completeness of parts while unpacking. Also
check for any mechanical damage or loose parts. In case of
transport damage inform the supplier immediately and do not
operate the instrument.
Positioning
Two positions are possible: According to picture 1 the front
feet are used to lift the instrument so its front points slightly
upward. (Appr. 10 degrees)
If the feet are not used (picture 2) the instrument can be
combined with many other HAMEG instruments.
In case several instruments are stacked (picture 3) the feet
rest in the recesses of the instrument below so the instru-
ments can not be inadvertently moved. Please do not stack
more than 3 instruments. A higher stack will become unstable,
also heat dissipation may be impaired.
Transport
Please keep the carton in case the instrument may require
later shipment for repair. Losses and damages during
transport as a result of improper packaging are excluded from
warranty!
Storage
Dry indoor storage is required. After exposure to extreme
temperatures, wait 2 hr before turning the instrument on.
Safety instructions
The instrument conforms to VDE 0411/1 safety standards
applicable to measuring instruments and it left the factory in
proper condition according to this standard. Hence it conforms
also to the European standard EN 61010-1 resp. to the inter-
national standard IEC 61010-1. Please observe all warnings
in this manual in order to preserve safety and guarantee
operation without any danger to the operator. According to
safety class 1 requirements all parts of the housing and the
chassis are connected to the safety ground terminal of the
power connector. For safety reasons the instrument must only
be operated from 3 terminal power connectors or via isolation
transformers. In case of doubt the power connector should
be checked according to DIN VDE 0100/610.
Do not disconnect the safety ground either inside
or outside of the instrument!
– The line voltage of the instrument must correspond to the
line voltage used.
– Opening of the instrument is only allowed to qualified
personnel
– Prior to opening, the instrument must be disconnected
from the line voltage and all other inputs/outputs.
In any of the following cases the instrument must be taken
out of service and locked away from unauthorized use:
– Visible damage
– Damage to the power cord
– Damage to the fuse holder
– Loose parts
– No operation
– After long term storage in an inappropriate environment,
e.g. open air or high humidity.
– Excessive transport stress
CAT II
The following remarks concern only the safety of the user.
Other aspects e.g. the maximum input voltage etc. are covered
in the specifications section of this manual and are to be
observed as well.
Measurements in circuits which are indirectly connected with
the mains supply are possible with adequate converters (e.g.
clamp-on ammeters) which fulfil at least the requirements of
the safety class of the measurement. The measurement
category of the converter specified by the manufacturer must
be considered.
Measurement categories CAT
The measurement categories were created with respect to
the different kind of transients incurred in practice. Transients
STOP
STOP
STOP
Important hints
HINT

37
Subject to change without notice
are short, fast, and fast-rise changes of voltage or current,
and may be periodic or non-periodic. The amplitude of
transients increases with decreasing distance from their
source.
CAT IV: Measurements at the source of a low voltage supply,
e.g. at electricity meters.
CAT III: Measurements inside a building, e.g. at distribution
sites, power switches, permanently installed mains
outlets, permanently mounted motors etc.
CAT II: Measurements in circuits which are directly
connected with the low voltage supply, e.g. household
appliances, portable tools etc.
CAT I: Electronic instruments and circuits which contain
circuit breakers resp. fuses.
Proper operating conditions
Operation in the following environments: industry, business
and living quarters, small industry. The instruments are
intended for operation in dry, clean environments. They must
not be operated in the presence of excessive dust, humidity,
nor chemical vapours in case of danger of explosion.
The maximum permissible ambient temperature during
operation is +10 to +40 deg. C. In storage or during transport
the temperature limits are: –40 to +70 deg. C. In case of
exposure to low temperature or if condensation is suspected,
the instrument must be left to stabilize for at least 2 hrs prior
to operation.
In principle the instrument may be used in any position,
however sufficient ventilation must be ensured. Operation for
extended periods of time requires the horizontal or tilted
(handle) position.
Nominal specifications are valid after 30 minutes warm-up at
23 deg. C. Specifications without tolerances are typical values
taken of average production units.
Warranty and Repair
HAMEG instruments are subject to a strict quality control. All
instruments are burned in for 10 hrs prior to shipment. Alm-
ost all early failures are detected by intermittent operation.
After burn-in a thorough test of all functions and of quality is
run, all specifications and operating modes are checked.
In case of claims during the two years warranty period please
contact the dealer from whom you purchased your HAMEG
STOP
STOP
STOP
instrument. Customers from the Federal Republic of Germany
may directly contact HAMEG for warranty processing in order
to speed up the procedure.
The proceeding of repairs during the warranty period is subject
to our terms of warranty which are available on our web-site
(http://www.hameg.com). Even after expiry of the warranty
period please do not hesitate to contact our HAMEG customer
service for repairs and spare parts.
Return Material Authorization (RMA):
Before sending back your instrument to HAMEG do
apply for a RMA number either by fax or on the
Internet: http://www.hameg.de.
If you do not have suitable packaging for the in-
strument on hand please contact the HAMAG sales
department (Tel.: [phone], E-mail:
[email protected]) to order an empty original
cardboard box.
Maintenance
The instrument does not require any maintenance. Dirt may
be removed by a soft moist cloth, if necessary adding a mild
detergent. (Water and 1 %.) Grease may be removed with
benzine (petrol ether). Displays and windows may only be
cleaned with a moist cloth.
Do not use alcohol, solvents or paste. Under no
circumstances should any fluid be allowed to get
into the instrument. If other cleaning fluids are
used damage to the lacquered or plastic surfaces
is possible.
Mains voltage
A main voltage of 115V and 230V can be chosen. Please check
whether the mains voltage used corresponds with the voltage
indicated by the mains voltage selector
30
on the rear panel.
If not, the voltage has to be changed.
Line fuse
The instrument has 2 internal line fuses: T 0.2 A. In case of a
blown fuse the instrument has to be sent in for repair. A change
of the line fuse by the customer is not permitted.
Power switch
Normally the power switch
28
on the rear
panel of the instrument should be stay in “ON“
position. If using the Standby-button on the
front panel, only the controls and the display
are turned off. The instrument itselfs 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 energized, 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 power switch on the back panel
has to be operated.
If the instrument is left unattended for some time,
the power switch on the rear panel has to be
operated. (Because of safety reasons!)
Important hints
CAT IV CAT III CAT II
Premises
In-house
installation
Permanently installed
machinery, distribution sites,
power conductors, mains
outlets close to the CAT IV
installation
Mains outlets for
household appliances,
portable tools, PC,
refrigerator etc.
Overhead lines
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FAX [phone] - TestEquipmentDepot.com

38 Subject to change without notice
Control elements
DISPLAY – 16 digit display
POWER – Stand by / ON
HOLD DISPLAY – storage of the displayed value
ZERO – 0-compensation of the measuring section
RM/LOCAL-pushbutton – Return to manual mode
VDC – Measurement of DC voltage
ADC – Measurement of DC current
VAC – Measurement of AC voltage with AC coupling
AAC – Measurement of AC current
VAC+DC – Measurement of AC voltage with DC coupling
11
Ω– Measurement of resistance, 2- and 4-wire
12
FREQ./PERIOD – Frequency and period measurement
with VAC
13
ϑPT - Measurement of temperature using a PT-sensor,
2- and 4-wire
14
- Diode test / Continuity test
15
ϑTH – Measurement of temperature using a
thermocouple, 2-wire
16
MAX – max. value during a test series
17
MIN – min. value during a test series
18
MENU – Call of the menu, acceptance of values entered
19
ESC – Leaving the menu without acceptance of the
values entered
20
– down: Switching to a higher range and scrolling
down the menu
21
AUTO – Activation/Deactivation of the auto range
function
22
ENTER – Special function: Parameter selection in the
logger menu
23
– up: Switching to a lower range and scrolling up the
menu
24
V SENSE – Input for measurements of voltage,
frequency, resistance, temperature
25
LO – Ground connection for inputs
24
and
26
26
A SOURCE – Input for current measurement
27
FUSE – 1 A / 250 V (FF) Measuring circuit fuse
Rear panelRear panel
Rear panelRear panel
Rear panel
28
Power receptacle with power switch
29
RS-232 Interface (Option: USB, IEEE-488)
30
Voltage selector (115 V / 230 V)
Control elements
12 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

39
Subject to change without notice
Introduction to the operation of the HM8112-3
Concept of the HM8112-3
Reference
The integrated AD converter has to be connected to a reference.
The characteristics of this reference determine the long term
stability of the instrument. The reference of HM8112-3 is therefore
a high precision reference device.
Integrated AD converters
Converters applying the multi slope method are used for AD
conversion.
Moving average
The value determined by the AD converter could be displayed
without prior computations, also the average calculated from
n – values could be shown. First of all 1 to n values will be
logged. Averaging over these values will be done, and sub-
sequently this average will be displayed. After 120 values the
next value n+1 will be quantified by the AD converter. The
primary measured value 1 will be abolished and a new average
will be calculated from the remaining values ( 2 to n) and from
the new value n+1. This has the advantage that peaks and
interferences will be smoothed.
Measurement of alternating values
Frequency, period
Frequency and period are both measured by a pulse-counting
circuit. Time base is 1 second. The first falling edge triggers
the measurement and starts the counter. For one second every
falling edge will trigger a counting pulse. After expiry of this
term the measurement circuit will wait for the next zero point.
Hence the signal’s period is measured. The time will be
measured until the next zero point occurs. The measurement
result determines the frequency of the signal and the period
will be calculated from the frequency. This combined
measurement of the number of zero points and of the period
of a signal allows the measurement of very small as well as
very high frequencies within a reasonable time. Applying of a
DC voltage results in a frequency displayed of 0 Hz.
As the period is calculated from the measured frequency
division by zero will be made. Therefore the instrument will
display „INF“ if the period of a DC voltage is measured („INF“
= infinity).
RMS rectifier
The AC voltage is measured by a high precision RMS rectifier
device. This device gauges a DC voltage proportional to the
applied AC voltage. This DC voltage is equivalent to the true
RMS value of the AC voltage.
Measurement of the crest factor
For crest factors exceeding 7 an AC voltage or current
measurement will be incorrect due to the true RMS converter.
Introduction to the operation of the HM8112-3
Especially before the first operation please pay attention to
the following points:
– The line voltage, indicated on the rear panel of the
instrument must correspond to the line voltage used.
– Operation is only allowed from 3 terminal connectors with
a safety ground connection or via isolation transformers
of class 2.
– No visible damage to the instrument.
– No damage to the line power cord.
– No loose parts in the instrument.
Factory settings
The following values are set by default:
– The measurement range is 10 VDC
– The sampling rate amounts to 100 ms
– The function „1:Filter“ is OFF
– The temperature is displayed in °C
– The selected temperature sensor is PT100
– The data logger is OFF
– The RS-232 interface is OFF
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40 Subject to change without notice
STOP
STOP
Control elements and display
Control elements and displays
Display
16 digit display for displaying measurement results, menu
selection and menu items.
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
energized, 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.
HOLD
“Freezing“ of the displayed measured value.
By pressing one of the function selection buttons to
15
or
MENU
18
the HOLD function is left.
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 ϑPT for PT sensors or ϑTH for
thermocouples.
Zero adjustment with temperature measurement
1. With regard to the type of temperature sensor one the
following measurement ranges must be chosen:
PT100 Ω2 wire / Ω4 wire 1 kΩrange
PT1000 Ω2 wire / Ω4 wire 10 kΩrange
Thermocouple VDC 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 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
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,
because the zero adjustment of the complete
measurement circuit is very important.
LOCAL
By sending a command via interface to the HM8112-3 the
instrument 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.
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. Naturally,
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
VDC
Direct voltage measurement up to 600 V. No auto range
function in 100 mV and 1 V ranges.
12 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
VA
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