Omega HHM31 User manual

OMEGA
HHM31
Digital Multimeter

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It is the policy of OMEGA to comply with all worldwide safety and EMC/EMI regulations that apply. OMEGA is constantly pursuing certification
of its products to the European New Approach Directives.OMEGA will add the CE mark to every appropriate device upon certification.
The information contained in this document is believed to be correct but OMEGA Engineering, Inc.accepts no liability for any errors it contains,
and reserves the right to alter specifications without notice.
WARNING: These products are not designed for use in, and should not be used for, patient connected application.

SAFETY INFORMATION
The following safety information must be observed to ensure maximum
personal safety during the operation of this meter:
1. Do not use the meter if the meter or test leads look damaged, or if you
suspect that the meter is not operating properly.
2.Thismeterisnotrecommendedforhighvoltageindustrialuse;forexample,
notfor measurementsof440 VACor600VAC industrial powermains. The
unit is intended for use with low energy circuits to 600VDC or AC or high
energy circuit to 250 VAC or DC. Accidental misuse by connection across
a high voltage, high energy power source when the meter is set up for mA
measurement may be very hazardous.
3. Turn off power to the circuit under test before cutting, unsoldering, or
breaking the circuit. Small amounts of current can be dangerous.
4.Usecautionwhenworkingabove60Vdcor30Vacrms.Suchvoltagespose
a shock hazard.
5. When Using the probes, keep your fingers behind the finger guards on the
probes.
6.Measuring voltage whichexceedsthe limits of themultimeter may damage
themeterandexposetheoperatortoashockhazard.Alwaysrecognizethe
meter voltage limits as stated on the front of the meter.
7.Ifthe equipment is used in a manner not specified bythemanufacturer,the
protection provided the equipment may be impaired.
1

2
SPECIFICATIONS
Display:3½digitliquidcrystaldisplay(LCD)withamaximumreadingof1999.
Polarity: Automatic, positive implied, negative polarity indication.
Overrange: (OL) or (-OL) is displayed.
Zero: Automatic.
Lowbatteryindication: the" "isdisplayedwhenthebatteryvoltagedrops
below the operating level.
Measurement rate: 2.5 times per second, nominal.
Operating Environment: 0°C to 40°C at < 70% relative humidity.
Storage Temperature: -20°C to 60°C, 0 to 80% R.H. with battery removed
from meter.
Accuracy: Stated accuracy at 23°C ± 5°C, <75% relative humidity.
Safety: According to EN61010-1 protection class II overvoltage category
(CAT II 600V) pollution degree 2.
Power: single standard 9-volt battery, NEDA 1604, JIS 006P, IEC 6F22.
Battery life: 200 hours typical.
Dimensions: 192mm (H) x 91mm (W) x 52.5mm (D).
Weight: 365g including battery.
Accessories: One pair test leads, One spare fuse installed, 9V battery and
Operating Instructions.

3
DC VOLTS
Ranges: 200mV,2V,20V,200V,600V
Resolution: 100µV
Accuracy: ±(0.35%rdg + 1dgt)
Input impedance: 10MW
Overload protection: 500VDC or AC rms on 200mV range
600VDC or AC rms on all other ranges
AC VOLTS (50Hz - 500Hz)
Ranges: 200mV,2V,20V,200V,600V
Resolution: 100µV
Accuracy: ±(1.0%rdg + 4dgts) on 200mV to 200V ranges
±(2.0%rdg + 4dgts) on 600V range
Input impedance: 10MW
Overload protection: 500VDC or AC rms on 200mV range
600VDC or AC rms on all other ranges
DC CURRENT
Ranges: 200µA,20mA,200mA,10A
Accuracy: ±(0.5%rdg + 1dgt) on µA,mA ranges
±(3.0%rdg + 1dgt) on 10A range
Input protection: 0.5A / 250V fast blow ceramic fuse
10A / 600V fast blow ceramic fuse
AC CURRENT (50Hz - 500Hz)
Ranges: 200µA,20mA,200mA,10A
Accuracy: ±(1.2%rdg + 4dgts) on µA,mA ranges
±(3.5%rdg + 4dgts) on 10A range
Input protection: 0.5A / 250V fast blow ceramic fuse
10A / 600V fast blow ceramic fuse

4
RESISTANCE
Ranges: 200W,2KW,20KW,200KW,2MW,20MW
Accuracy: ±(0.4%rdg + 4dgts) on 200Wrange
±(0.4%rdg + 1dgt) on 2KWto 2MWranges.
±(3.0%rdg + 4dgts) on 20MWrange
Open circuit volts: 0.3Vdc (3.0Vdc on 200Wrange)
Overload protection: 500VDC or AC rms
CONTINUITY
Audible indication: less than 100W
Overload protection: 500VDC or AC rms
DIODE TEST
Test current: 1.0mA±0.6mA
Accuracy: ±(3.0%rdg + 3dgt)
Open circuit volts: 3.0Vdc typical
Overload protection: 500VDC or AC rms
CAPACITANCE
Ranges:2nF,20nF,200nF,2µF,20µF
Accuracy: ±(2.0%rdg + 10dgts)
Test frequency: 2.5Hz

5
FREQUENCY (Autoranging)
Ranges: 2KHz,20KHz,200KHz,2000KHz,15MHz
Accuracy: ±(0.1%rdg + 1dgt)
Sensitivity: 2.0Vrms min
Overload protection: 500VDC or AC rms
Effect Reading: 10 - 1999
TEMPERATURE ELECTRICAL
Temperature Scale: Celsius or Fahrenheit user-selectable
Measurement Range: -50°C to 1300°C, (-58°F to 2000°F)
Resolution: 1°C or 1°F, 0.1°C or 0.1°F
Accuracy: Accuracy is specified for operating temperatures over the range
of18°Cto28°C(64°Fto82°F),for1 year,notincludingthermocoupleerror.
±(0.3%rdg + 1°C) -50°C to 1000°C
±(0.5%rdg + 1°C) 1000°C to 1300°C
±(0.3%rdg + 2°F) -58°F to 2000°F
Temperature Coefficient: 0.1 times the applicable accuracy specification
per°Cfrom0°Cto18°Cand28°Cto50°C(32°Fto64°Fand82°Fto122°F).
Input Protection: 24V dc or 24V ac rms maximum input voltage on any
combination of input pins.
InputConnector:Acceptsstandardminiaturethermocoupleconnectors(flat
blades spaced 7.9mm, center to center).

6
OPERATION
Before taking any measurements, read the Safety Information Section.
Always examine the instrument for damage, contamination (excessive dirt,
grease, etc.) and defects. Examine the test leads for cracked or frayed
insulation. If any abnormal conditions exist do not attempt to make any
measurements.
Max. Hold and Back-Light ( >2sec) Switch :
Press "MAX" to toggle in and out of the Maximun Hold mode.(holding the
highest reading.) In the MAX mode, the MAX annunciator is displayed and
maximun reading are stored in display register, If the new reading is higher
than the reading being displayed, the higher reading is transferred to the
display register. A "higher" reading is defined as the reading with the higher
absolute value.
The MAX hold function is disable in the frequency count mode, but the MAX
annunciator is still displayed.
Press this button for two seconds to turn the Back-Light on. As this also
activates the MAX hold mode, briefly press the button to return to normal
display. The Back-Light will switch-off automatically after about 20 seconds.

7
T1,T2, T1-T2 Temperature Measurement
WARNING
Remove test leads being measured.
1. Set the Function/Range switch to the T1 thermocouple, T2 thermocouple
or the difference between the two thermocouples (T1-T2), and The LCD
indicates which is selected.
2. Selecting the Temperature Scale:
Readings are displayed in either degrees Celsius(°C) or degrees
Fahrenheit(°F). To change the temperature scale, press the "°C/°F "key.
3. Selecting the Display Resolution
The meter allows two choices of resolution:
High resolution: 0.1°C or 0.1°F
Low resolution: 1.0°C or 1.0°F
To select the alternate display resolution, press the corresponding "0.1°/
1°" key.
4. Connect a type k thermocouple to the jack on the instrument. Place the
probe or thermocouple tip on or in the material to be measured and take
the temperature reading directly from the display.

8
Voltage Measurements
1. Connect the red test lead to the "VW" jack and the black test lead to the
"COM" jack.
2. Set the Function/Range switch to the desired voltage range and press the
"AC/DC" switch to toggle between the desired voltage type. If magnitude
of voltage is not known, set switch to the highest range and reduce until a
satisfactory reading is obtained.
3. Connect the test leads to the device or circuit being measured.
4.Fordc,a(-)signisdisplayedfornegativepolarity;positivepolarityisimplied.
Current Measurements
1. Set the Function/Range switch to the desired current range and press the
"AC/DC" switch toggle between to the desired current type.
2.Forcurrentmeasurementslessthan200mA,connecttheredtestleadtothe
µAmA jack and the black test lead to the COM jack.
3.Forcurrentmeasurementsover200mAorgreater,connecttheredtestlead
to the 10A jack and the black test lead to the COM jack.
4. Remove power from the circuit under test and open the normal circuit path
wherethemeasurementistobetaken.Connectthemeterinserieswiththe
circuit.
5.Usecautionwhenmeasuring10ampson10Arangefor60s,pleasewaiting
for 10 minutes for next measurement of 10 amps for safety reason.

9
Resistance and Continuity Measurements
1.SettheFunction/Rangeswitchtothedesiredresistancerangeorcontinuity
position.
2. Remove power from the equipment under test.
3. Connect the red test lead to the "VW" jack and the black test lead to the
"COM" jack.
4. Touch the probes to the test points. In ohms, the value indicated in the
display is the measured value of resistance. In continuity test, the beeper
sounds continuously, if the resistance is less than 100W.
WARNING
The accuracy of the functions might be slightly affected, when exposed to
a radiated electromagnetic field environment, eg, radio, telephone or
similar.

10
Diode Tests
1. Connect the red test lead to the "VW" jack and the black test lead to the
"COM" jack.
2. Set the Function/Range switch to the " " position.
3. Turn off power to the circuit under test.
4.Touchprobestothediode.A forward-voltagedrop isabout 0.6V(typical for
a silicon diode).
5. Reverse probes. If the diode is good, "OL" is displayed. If the diode is
shorted, ".000" or another number is displayed.
6. If the diode is open, "OL" is displayed in both directions.
7.Ifthejunctionismeasuredinacircuitandalowreadingisobtainedwithboth
lead connections, the junction may be shunted by a resistance of less than
1kW. In this case the diode must be disconnected from the circuit for
accurate testing.
Capacitance Measurements
1. Set the Function/Range switch to the desired capacitance range.
2. Never apply an external voltage to the sockets. Damage to the meter
may result.
3. Insert the capacitor leads directly into the socket.
4. Read the capacitance directly from the display.

11
Frequency Measurements
1. Set the Function/Range switch to the Hz position.
2. Connect the red test lead to the "VW" jack and the black test lead to the
"COM" jack.
3.Connect thetest leadstothe pointof measurementandread thefrequency
from the display.

12
Battery Replacement
Poweris suppliedby a9 volt"transistor"battery. (NEDA1604 IEC6F22).The
""appearsontheLCDdisplaywhenreplacementisneeded.Toreplacethe
battery, remove the two screws from the back of the meter and lift off the
battery case. Remove the battery from battery contacts.
Fuse Replacement
If no current measurements are possible, check for a blown overload protec-
tion fuse. There are two fuses; F1 for the "mA" jack and F2 for the "10A" jack.
For access to fuses, remove the four screws from the back of the meter and
liftoff the battery cover and case. Replace F1 only with the originaltype 0.5A/
250V, fast acting ceramic fuse. Replace F2 only with the original type 10A/
600V, fast acting ceramic fuse.
Cleaning
Periodically wipe the case with a damp cloth and detergent, do not use
abrasives or solvents.
MAINTENANCE
WARNING
Remove test leads before changing battery or fuse
or performing any servicing.

1
HHM31 CALIBRATION PROCEDURE
Note: Only qualified technicians who have access to the items, as following should
perform the following calibration procedure.
Equipments: The class of calibrator had better 10 times greater than the measured meter.
DCV Calibration
Set the function /range to the DC 200mV，then apply 190.0mV to the V-Wand
COM input jacks.
Adjust R41 until display reads 1900±1dgt then disconnect the source from the
measured meter.
DCA Calibration
Set the function /range to the 10A, set the output of the current calibrator for
1.9A, and connect it the 10A and COM jacks.
Adjust the shunt resistor until the display reads 1.9A, if the reading over 1.9A
then add solder onto the shunt resistor, below 1.9Athen cut CuMn Shunt Resistor
slightly with diagonal cutters or shave away some of solder from the Shunt.
Temperature Calibration
Insert the K type thermocouple to the female connector, and the other side of
this probe to Temperature Calibrator. We must allow the K type to stabilize for at
least 1 minute and make sure “+” and “-“ polarity is right position.
1. Set the range to the T1/0.1°C, and then apply 0°C to T1 input (T2 input open)
adjust R845 and R846 (fine adj.) until LCD reading reads 0.0±0.1°C.
2. Set the range to the T1/0.1°F, and then apply 0°F to T1 input (T2 input open)
adjust R804 until LCD reading reads 0.0±0.1°F.
3. Set the range to the T1/0.1°F, and then apply 165°F to T1 input (T2 input
open) adjust R891 until LCD reading reads 165.0±0.1°F.
4. Set the range to the T1/1°F, and then apply 1832°F to T1 input (T2 input
open) adjust R824 until LCD reading reads 1832±1°F.
5. Set the range to the T1/1°C, and then apply 1000°C to T1 input (T2 input
open) adjust R806 until LCD reading reads 1000±0°C.
6. Set the range to the T2/0.1°C, and then Apply 0°C to T2 input (T1 input open)
adjust R82 and R83 (fine adj.) until LCD reading reads 0.0±0.1°C.

WARRANTY / DISCLAIMER
OMEGA ENGINEERING, INC. warrants this unit to be free of defects in materials and workmanship for a period of 13 months
from date of purchase. OMEGA Warranty adds an additional one (1) month grace period to the normal one (1) year product
warranty tocoverhandlingandshippingtime.This ensures that OMEGA's customersreceivemaximumcoverageon eachproduct.
If the unit should malfunction, it must be returned to the factory for evaluation. OMEGA's Customer Service Department will issue
an Authorized Return (AR) number immediately upon phone or written request.Upon examination by OMEGA, if the unit is found
to be defective it will be repaired or replaced at no charge. OMEGA's WARRANTY does not apply to defects resulting from any
action of the purchaser, including but not limited to mishandling, improper interfacing, operation outside of design limits, improper
repair, or unauthorized modification.ThisWARRANTY isVOID if the unit shows evidence of having been tampered with or shows
evidence of being damaged as a result of excessive corrosion; or current, heat moisture or vibration; improper specification;
misapplication; misuse or other operating conditions outside of OMEGA's control. Components which wear are not warranted,
including but not limited to contact points, fuses, and triacs.
OMEGA is pleased to offer suggestions on the use of its various products.However,OMEGA neither assumes responsibility
for any omissions or errors nor assumes liability for any damages that result from the use of its products in accordance
with information provided by OMEGA, either verbal or written. OMEGA warrants only that the parts manufactured by it
will be as specified and free of defects. OMEGA MAKES NO OTHERWARRANTIES OR REPRESENTATIONS OF ANY KIND
WHATSOEVER, EXPRESSED OR IMPLIED, EXCEPT THAT OF TITLE AND ALL IMPLIED WARRANTIES INCLUDING ANY
WARRANTY OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE HEREBY DISCLAIMED.
LIMITATION OF LIABILITY:The remedies of purchaser set forth herein are exclusive and the total liability of OMEGA with
respect to this order, whether based on contract, warranty, negligence, indemnification,strict liability or otherwise, shall
not exceed the purchase price of the component upon which liability is based. In no event shall OMEGA be liable for
consequential, incidental or special damages.
CONDITIONS: Equipment sold by OMEGA is not intended to be used, nor shall it be used: (1) as a "Basic Component" under 10
CFR 21 (NRC), used in or with any nuclear installation or activity; or (2) in medical applications or used on humans. Should any
Product(s) be used in or with any nuclear installation or activity, medical application, used on humans, or misused in any way,
OMEGA assumes no responsibility as set forth in our basicWARRANTY / DISCLAIMER language, and additionally, purchaser will
indemnify OMEGA and hold OMEGA harmless from any liability or damage whatsoever arising out of the use of the Product(s) in
such a manner.
RETURN REQUESTS / INQUIRIES
Direct all warranty and repair requests/inquiries to the OMEGA Customer Service Department. BEFORE RETURNING ANY
PRODUCT(S) TO OMEGA, PURCHASER MUST OBTAIN AN AUTHORIZED RETURN (AR) NUMBER FROM OMEGA'S
CUSTOMER SERVICE DEPARTMENT (IN ORDER TO AVOID PROCESSING DELAYS).The assigned AR number should then
be marked on the outside of the return package and on any correspondence.
The purchaser is responsible for shipping charges, freight, insurance and proper packaging to prevent breakage in transit.
FOR WARRANTY RETURNS, please have the following
information available BEFORE contacting OMEGA:
1. P.O. number under which the product was PURCHASED.
2. Model and serial number of the product under warranty, and
3. Repair instructions and/or specific problems relative to the
product.
FOR NON-WARRANTY REPAIRS, consult OMEGA for
current repair charges.Have the following information
available BEFORE contacting OMEGA:
1. P.O. number to cover the COST of the repair.
2. Model and serial number of product , and
3. Repair instructions and/or specific problems relative to the
product.
OMEGA's policy is to make running changes, not model changes, whenever an improvement is possible.This affords our customers the latest
in technology and engineering. OMEGA is a registered trademark of OMEGA ENGINEERING, INC.© Copyright 1999 OMEGA ENGINEERING,
INC. All rights reserved. This document may not be copied, photocopied, reproduced, translated, or reduced to any electronic medium or
machine-readable from, in whole or in part, without prior written consent of OMEGA ENGINEERING, INC.

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Process Measurement and Control?
OMEGA...Of Course!
TEMPERATURE
þThermocouple, RTD & Thermistor
Probes, Connectors, Panels & Assemblies
þWire: Thermocouple, RTD & Thermistor
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Instruments
M-3194/0799