HT HT321 User manual

Copyright HT ITALIA 2012 Release EN 2.00 - 19/04/2012
ENGLISH
User manual

HT321 - HT322
EN - 1
Table of contents:
1.SAFETY PRECAUTIONS AND PROCEDURES..........................................................2
1.1.Preliminary ........................................................................................................................ 2
1.2.During use......................................................................................................................... 3
1.3.After use............................................................................................................................ 3
1.4.Measuring (overvoltage) categories definitions................................................................. 3
2.GENERAL DESCRIPTION...........................................................................................4
3.PREPARATION FOR USE...........................................................................................4
3.1.Initial.................................................................................................................................. 4
3.2.Supply voltage................................................................................................................... 4
3.3.Calibration......................................................................................................................... 4
3.4.Storage.............................................................................................................................. 4
4.OPERATING INSTRUCTIONS.....................................................................................5
4.1.Instrument description....................................................................................................... 5
4.1.1.Front panel description............................................................................................................... 5
4.2.Description of function keys .............................................................................................. 6
4.2.1.HOLD Key................................................................................................................................... 6
4.2.2.R (RANGE) Key.......................................................................................................................... 6
4.2.3.MAX Key..................................................................................................................................... 6
4.2.4.SEL Key...................................................................................................................................... 6
4.2.5.Backlight key (only HT322) ................................................................................................. 6
4.2.6.Auto Power OFF......................................................................................................................... 6
4.3.Measurements................................................................................................................... 7
4.3.1.DC Voltage measurement.......................................................................................................... 7
4.3.2.AC Voltage measurement .......................................................................................................... 8
4.3.3.Resistance measurement........................................................................................................... 9
4.3.4.Diode test and Continuity test .................................................................................................. 10
4.3.5.Temperature measurement (only HT322)................................................................................ 11
5.MAINTENANCE..........................................................................................................12
5.1.General information......................................................................................................... 12
5.2.Battery replacement........................................................................................................ 12
5.3.Cleaning.......................................................................................................................... 12
5.4.End of life ........................................................................................................................ 12
6.TECHNICAL SPECIFICATIONS.................................................................................13
6.1.Technical features...........................................................................................................13
6.1.1.Safety........................................................................................................................................ 14
6.1.2.General data............................................................................................................................. 14
6.2.Environment.................................................................................................................... 14
6.2.1.Environmental conditions ......................................................................................................... 14
6.3.Accessories..................................................................................................................... 14
6.3.1.Standard accessories............................................................................................................... 14
6.3.2.Optional accessories................................................................................................................ 14
7.SERVICE....................................................................................................................15
7.1.Warranty conditions......................................................................................................... 15
7.2.After-sale service............................................................................................................. 15

HT321 - HT322
EN - 2
1. SAFETY PRECAUTIONS AND PROCEDURES
This meter is compliance with safety Standard IEC/EN61010-1 related to electronic
measuring instruments. For your own safety and to avoid damaging the instrument follow
the procedures described in this instruction manual and read carefully all notes preceded
by this symbol .
When taking measurements:
Avoid doing that in humid or wet places.
Avoid doing that in rooms where explosive gas, combustible gas, steam or excessive
dust is present.
Keep you insulated from the object under test.
Do not touch exposed metal parts such as test lead ends, sockets, fixing objects,
circuits etc.
Avoid doing that if you notice anomalous conditions such as breakages, deformations,
fractures, leakages of battery liquid, blind display etc.
Be particularly careful when measuring voltages exceeding 20V to avoid risks of
electrical shocks.
The following symbols are used:
CAUTION - refer to the instruction manual - an improper use may damage the
instrument or its components.
Danger high voltage: risk of electric shocks.
Double insulated meter.
AC voltage.
DC voltage.
1.1. PRELIMINARY
This instrument has been designed for use in environments of pollution degree 2
It can be used for VOLTAGE measurements on installations of CAT III 1000V or CAT
IV 600V
This instrument is not suitable for AC voltage and current measurements of not
sinusoidal signals
Only the original test leads supplied along with the instrument guarantee compliance
with the safety standards in force. They must be in a good conditions and, if necessary,
replaced with identical ones
Do not test nor connect to any circuit exceeding the specified overload protection.
Do not take measurements under environmental conditions exceeding the limits
indicated in § 6.1.1. and § 6.2.1
Make sure that batteries are correctly installed
Before connecting the test probes to the installation make sure that the rotary selector
is positioned on the right function
Make sure that LCD and rotary selector indicate the same function

HT321 - HT322
EN - 3
1.2. DURING USE
Read the recommendations which follow and the instructions in this manual:
CAUTION
An improper use may damage the instrument and/or its components or injure
the operator.
When changing the range, first disconnect the test leads from the circuit under test in
order to avoid any accident
When the instrument is connected to measuring circuits never touch any unused
terminal
When measuring resistors do not add any voltage. Although there is a protection
circuit, excessive voltage could cause malfunctioning.
If during measurement the displayed values remain constant check whether the HOLD
function is active
1.3. AFTER USE
After using the instrument turn it off.
If you expect not to use the instrument for a long period remove the battery to avoid
leakages of battery liquids which may damage its inner components.
1.4. MEASURING (OVERVOLTAGE) CATEGORIES DEFINITIONS
IEC/EN61010-1: Safety requirements for electrical equipment for measurement, control
and laboratory use, Part 1: General requirements, gives a definition of measuring
category, usually called overvoltage category. § 6.7.4: Measuring circuits:
(OMISSIS)
Circuits are divided into the following measurement categories:
Measurement category IV is for measurements performed at the source of the low-
voltage installation.
Examples are electricity meters and measurements on primary overcurrent protection
devices and ripple control units.
Measurement category III is for measurements performed in the building installation.
Examples are measurements on distribution boards, circuit breakers, wiring, including
cables, bus-bars, junction boxes, switches, socket-outlets in the fixed installation, and
equipment for industrial use and some other equipment, for example, stationary motors
with permanent connection to fixed installation.
Measurement category II is for measurements performed on circuits directly
connected to the low voltage installation..
Examples are measurements on household appliances, portable tools and similar
equipment.
Measurement category I is for measurements performed on circuits not directly
connected to MAINS.
Examples are measurements on circuits not derived from MAINS, and specially
protected (internal) MAINS-derived circuits. In the latter case, transient stresses are
variable; for that reason, the norm requires that the transient withstand capability of the
equipment is made known to the user.

HT321 - HT322
EN - 4
2. GENERAL DESCRIPTION
This meter performs the herewith measurements:
DC Voltage
AC sine voltage
Resistance
Continuity test
Diode test
Temperature with type K probe (only HT322)
All selectable by means of a 6-position rotary selector (including OFF position). Also are
available the HOLD key to hold the displayed value, the Rkey for manual selection of
measure ranges, the MAX key for measure of maximum value and SEL key for selection
between diode test and continuity test and temperature measures in °C or °F (only
HT322).
The selected quantity is displayed with indication of measuring unit and active functions.
The instrument disposes of an Auto Power Off function consisting in an automatic
switching off 15 minutes after last selector rotation.
3. PREPARATION FOR USE
3.1. INITIAL
This instrument was checked both mechanically and electrically prior to shipment. All
possible cares and precautions were taken to let you receive the instrument in perfect
conditions. Notwithstanding we suggest you to check it rapidly (eventual damages may
have occurred during transport – if so please contact the local distributor from whom you
bought the item).
Make sure that all standard accessories mentioned in § 6.3.1 are included. Should you
have to return back the instrument for any reason please follow the instructions mentioned
in § 7.
3.2. SUPPLY VOLTAGE
The instrument is supplied by 2x1.5V batteries type IEC AAA LR03. When batteries are
low, a low battery indication is displayed. To replace/insert batteries please refer to § 5.2.
3.3. CALIBRATION
The instrument complies with the technical specifications contained in this manual and
such compliance is guaranteed for 1 year. Annual recalibration is recommended.
3.4. STORAGE
After a period of storage in extreme environmental conditions exceeding the limits
mentioned in § 6.2.1 let the instrument resume normal measuring conditions before using
it.

HT321 - HT322
EN - 5
4. OPERATING INSTRUCTIONS
4.1. INSTRUMENT DESCRIPTION
4.1.1. Front panel description
CAPTION:
1. LCD
2. HOLD Key
3. RKey
4. MAX Key
5. SEL Key
6. Backlight Key(For HT322)
7. Function selector
8. COM input terminal
9. Vinput terminal (for 321) COM
and V°C/°F input terminal (for
HT322)
Fig. 1: Instrument description

HT321 - HT322
EN - 6
4.2. DESCRIPTION OF FUNCTION KEYS
4.2.1. HOLD Key
By pressing HOLD key the measured value is frozen on the display where the symbol
"HOLD" appears. Pressing again HOLD to disable this function and resume normal
operation.
4.2.2. R (RANGE) Key
By pressing Rkey, the manual mode is activated and the “AUTO” symbol disappears from
the display. Press R cyclically to change the measuring range and fix the decimal point on
the display.
To exit this function keep Rkey pressed for at least 1 second or rotate the selector to
another position.
4.2.3. MAX Key
By pressing MAX key, maximum value are measured. The symbol corresponding “MAX” is
displayed. This value is stored and automatically updated as soon as an higher value is
measured by meter. Press MAX key again or rotate the selector to another position to exit
from this function.
4.2.4. SEL Key
By pressing SEL key the selection of a double measured functions which are present at
display is possible. In particular this key is active only in /position to select between
diode test and continuity test or in °C°F position (only HT322) position to select between
°C and °F temperature measure.
4.2.5. Backlight key (only HT322)
By pressing and hold key for about 3s it’s possible to activate the backlight function on
the display. By pressing and hold key again for about 3s to exit from the function or
waiting the automatically disable after some seconds. The function is available on each
position of the rotary selector.
4.2.6. Auto Power OFF
The instrument automatically turns off 15 minutes after last pressure of keys or last
selector rotation. To resume operation turn the selector on OFF and turn on the instrument
again.

HT321 - HT322
EN - 7
4.3. MEASUREMENTS
4.3.1. DC Voltage measurement
CAUTION
The maximum input for DC voltage is 600V. Do not attempt to measure
higher voltages to avoid electrical shocks or damages to the instrument.
Fig. 2: Using the meter for DC Voltage measurement
1. Switch on V.
2. Pressing the Rkey to select the correct range or using the Autorange feature (see §
4.2.2). If the voltage value under test is unknown, select the highest range.
3. Insert the test leads into the jacks, the red plug into V(for HT321) /
V°C°F (for HT322) jack and black plug into COM jack.
4. Connect the red and black test leads to the positive and negative poles of the circuit
under test respectively (see Fig. 2). The voltage value is displayed
5. If the message "O.L" is displayed select a higher range
6. The symbol "-" on the instrument display indicates that voltage has opposite direction
with regard to the connection of Fig. 2
7. For HOLD function and Maximum value measurement please refer to § 4.2

HT321 - HT322
EN - 8
4.3.2. AC Voltage measurement
CAUTION
The maximum input for AC voltage is 600V. Do not attempt to measure
higher voltages to avoid electrical shocks or damages to the instrument.
Fig. 3: Using the instrument for AC Voltage measurement
1. Switch on
2. Pressing the Rkey to select the correct range or using the Autorange feature (see §
4.2.2). If the voltage value under test is unknown, select the highest range
3. Insert the test leads into the jacks, the red plug into V(for HT321) /
V°C°F (for HT322) jack and black plug into COM jack
4. Connect the test leads to the circuit under test (see Fig. 3). The voltage value is
displayed
5. If the message "O.L" is displayed select a higher range
6. For HOLD function and Maximum value measurement please refer to § 4.2

HT321 - HT322
EN - 9
4.3.3. Resistance measurement
CAUTION
Before taking resistance measurements in circuit remove power from the
circuit being tested and discharge all capacitors.
Fig. 4: Using the instrument for Resistance measurement
1. Switch on 
2. Pressing the Rkey to select the correct range or using the Autorange feature (see §
4.2.2). If the resistance value under test is unknown, select the highest range.
3. Insert the test leads into the jack, the red plug into V(For HT321) / V°C°F
(For HT322) jack and black plug into COM jack.
4. Connect the test leads to the circuit under test (see Errore. L'origine riferimento non
è stata trovata.). The resistance value is displayed
5. Indications as ".value k" or ".value M" (respectively for 2kor 2M) mean
0.valuekand 0.valueM. The zero before comma is not displayed.
6. If the message "O.L" is displayed a higher range must be selected.
7. For HOLD function and Maximum value measurement please refer to § 4.2.

HT321 - HT322
EN - 10
4.3.4. Diode test and Continuity test
CAUTION
Before taking resistance measurements in circuit remove power from the
circuit being tested and discharge all capacitors.
Fig. 5: Using the instrument for Diode test
1. Switch on /
2. Insert the test leads into the jack, the red plug into V(for HT321) / V°C°F
(for HT322) jack, and black plug into COM jack (see Fig. 5)
3. Connect the test leads to the diode under test observing the proper polarities indicated in
Fig. 5. The threshold voltage value expressed in mV under this situation is displayed
4. If the message "O.L" is displayed the diode terminals are reversed, the diode P-N
junction is damaged
5. For Continuity test switch on /then push “SEL” button
6. Insert the test leads into the jack, the red plug into V(for HT321) / V°C°F
(for HT322) jack and black plug into COM jack
7. Connect the test leads to the circuit under test (see Fig. 4)
8. The resistance value is displayed and the instrument emits a sound signal if the
resistance value is <120
9. The message "O.L." on the display indicates that the resistance value is higher than
2k

HT321 - HT322
EN - 11
4.3.5. Temperature measurement (only HT322)
Fig. 6: Using the instrument for Temperature measurement
1. Switch on °C°F.
2. Pressing SEL key to select °C or °F measurements
3. Insert the T10 adapter optional accessory into V°C°F jack, and COM jack with
respect of red and black colours (see Fig. 6)
4. Connect the optional K probe (see § 6.3.2) into the adapter with respect the correct
positive and negative polarity then reading will be displayed
5. For HOLD function and Maximum value measurement please refer to § 4.2

HT321 - HT322
EN - 12
5. MAINTENANCE
5.1. GENERAL INFORMATION
This is a precision instrument. To guarantee its performances be sure to use it according to
these instructions and keep it stored on suitable environmental conditions. Do not expose
it to high temperatures or humidity or direct sunlight. Be sure to turn it off after use. If you
expect not to use the instrument for a long period remove batteries to avoid leakages of
battery liquid which could damage the its inner components.
5.2. BATTERY REPLACEMENT
When the low battery indication " " is displayed the batteries are to be replaced.
CAUTION
Before replacing the battery disconnect test leads from any energised
circuits to avoid electrical shocks.
1. Turn off the instrument.
2. Disconnect the test leads from the input terminals.
3. Remove the fixing screws from the back case and detach it.
4. Replace the battery with a new one of the same type (refer to § Errore. L'origine
riferimento non è stata trovata.) observing the proper polarities.
5. Replace the back case and screws.
6. Use the appropriate battery disposal methods for your area.
5.3. CLEANING
To clean the instrument use a soft dry clothe. Never use a wet cloth, solvents or water.
5.4. END OF LIFE
Caution: this symbol indicates that equipment and its accessories shall be
subject to a separate collection and correct disposal

HT321 - HT322
EN - 13
6. TECHNICAL SPECIFICATIONS
6.1. TECHNICAL FEATURES
Accuracy is indicated as [%reading + (number of digits*resolution)] at 23°C±5°C,<75%HR
DC Voltage
Range Resolution Accuracy Input Impedance Overload protection
200mV 0.1mV
(0.8%rdg +1dgt) 10M600VDC/ACrms
2V 0.001V
20V 0.01V
200V 0.1V
600V 1V
(1.0%rdg +2dgt)
AC Voltage
Range Resolution Accuracy
(45 400Hz) Input Impedance Overload protection
200mV 0.1mV not declared
10M600VCC/CArms
2V 0.001V
(1.5%rdg+3dgt)
20V 0.01V
200V 0.1V
600V 1 V
Resistance
Range Resolution Accuracy Max Open
Loop Voltage Overload protection
2000.1(1.0%rdg + 8dgt)
About 3.0V 600VDC/Acrms
(<30sec.)
2k0.001k
(1.0%rdg + 3dgt)
20k0.01k
200k0.1k
2M0.001M
20M10k(3.0%rdg + 3dgt)
Diode Test
Range Resolution Max Open
Loop Voltage Overload protection
1mV About 1.5Vdc 600Vrms (< 30sec.)
Continuity Test
Range Beeper Max Open Loop
Voltage Overload protection
<120About 1.5Vdc 600Vrms (< 30sec.)
Temperature with K probe (only HT322)
Range Resolution Accuracy Overload protection
-40°C ÷ 1°C 1°C 5°C
600VDC/Acrms (<30sec.)
0°C ÷ 800°C (2.0%rdg + 3dgt)
-40°F ÷ 31°F 1°F 9°F
32°F ÷ 1382°F (2.0%rdg + 5dgt)

HT321 - HT322
EN - 14
6.1.1. Safety
The instrument complies with: IE/EN61010-1
Insulation: double insulation
Pollution degree: 2
Overvoltage category: CAT III 1000V, CAT IV 600V
Max height of use: 2000m (6561ft)
6.1.2. General data
Mechanical characteristics
Dimensions (L x W x H): 163 x 88 x 48mm (6.4 x 3.5 x 1.9in)
Weight (including battery): 280g (9.9 ounces)
Power supply
Battery type: 2 x1.5V batteries type AAA MN2400 LR03 AM4
Indication of low battery: symbol " " is displayed
Battery life: Approx. 220 hours
Display
Specifications: 3½ LCD with max. reading 1999 counts +
symbol and decimal point
6.2. ENVIRONMENT
6.2.1. Environmental conditions
Reference temperature: 23 ± 5°C; 73 ± 41°F
Working temperature: -5 ÷ 40°C; 23 ÷ 104°F
Relative humidity: <80% HR
Storage temperature: -10 ÷ 60°C; 14 ÷ 140°F
Storage humidity: <70% HR
This product conforms to the prescriptions of the European directive on low voltage
2006/95/EEC (LVD) and to EMC directive 2004/108/EEC.
6.3. ACCESSORIES
6.3.1. Standard accessories
Test leads
Batteries
B80: carrying case
User manual
6.3.2. Optional accessories
Couple of test leads Cod. 4413-2
Adapter for connection type K probe (HT322 only) Cod. T10
K-type probe for air and gas temperature (HT322 only) Cod. TK107
K-type probe for semisolid substance temperature (HT322 only) Cod. TK108
K-type probe for liquid substance temperature (HT322 only) Cod. TK109
K-type probe for surface temperature (HT322 only) Cod. TK110
K-type probe for surface temperature with 90° tip (HT322 only) Cod. TK111

HT321 - HT322
EN - 15
7. SERVICE
7.1. WARRANTY CONDITIONS
This instrument is guaranteed against material or production defects, in accordance with
our general sales conditions. During the warranty period the manufacturer reserves the
right to decide either to repair or replace the product.
Should you need for any reason to return back the instrument for repair or replacement
take prior agreements with the local distributor from whom you bought it. Do not forget to
enclose a report describing the reasons for returning (detected fault). Use only original
packaging. Any damage occurred in transit due to non original packaging will be charged
anyhow to the customer.
The manufacturer will not be responsible for any damage to persons or things.
The warranty doesn’t apply to:
Accessories and batteries (not covered by warranty).
Repairs made necessary by improper use (including adaptation to particular
applications not foreseen in the instructions manual) or improper combination with
incompatible accessories or equipment.
Repairs made necessary by improper shipping material causing damages in transit.
Repairs made necessary by previous attempts for repair carried out by non skilled or
unauthorized personnel.
Instruments for whatever reason modified by the customer himself without explicit
authorization of our Technical Dept.
The contents of this manual may not be reproduced in any form whatsoever without the
manufacturer’s authorization.
Our products are patented and our logotypes registered. We reserve the right to
modify specifications and prices in view of technological improvements or
developments which might be necessary.
7.2. AFTER-SALE SERVICE
Shouldn’t the instrument work properly, before contacting your distributor make sure that
batteries are correctly installed and working, check the test leads and replace them if
necessary. Make sure that your operating procedure corresponds to the one described in
this manual.
Should you need for any reason to return back the instrument for repair or replacement
take prior agreements with the local distributor from whom you bought it. Do not forget to
enclose a report describing the reasons for returning (detected fault). Use only original
packaging. Any damage occurred in transit due to not original packaging will be charged
anyhow to the customer.
The manufacturer will not be responsible for any damage to persons or things.