ENGLISH
User manual
Copyright HT ITALIA 2010 Release EN 1.01 - 19/01/2011
HT21
Table of Content:
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. Hz% key ...................................................................................................................................... 6
4.2.3. REL key ...................................................................................................................................... 6
4.2.4. MODE key ...................................................................................................................... ............ 6
4.2.5. 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 and Continuity Test measurements ......................................................................... 9
4.3.4. Diode test.................................................................................................................................. 10
4.3.5. Frequency and Duty Cycle measurements .............................................................................. 11
4.3.6. Capacitance measurement ...................................................................................................... 12
5. MAINTENANCE .......................................................................................................... 13
5.1. General information ......................................................................................................... 13
5.2. Battery replacement ........................................................................................................ 13
5.3. Cleaning .......................................................................................................................... 13
5.4. End of life ........................................................................................................................ 13
6. TECHNICAL SPECIFICATIONS ................................................................................. 14
6.1. Technical features ........................................................................................................... 14
6.1.1. Safety ........................................................................................................................................ 15
6.1.2. General data ............................................................................................................................. 15
6.2. Environment .................................................................................................................... 15
6.2.1. Environmental conditions ......................................................................................................... 15
6.3. Accessories ..................................................................................................................... 15
6.3.1. Standard accessories ............................................................................................................... 15
7. SERVICE .................................................................................................................... 16
7.1. Warranty conditions......................................................................................................... 16
7.2. After-sale service............................................................................................................. 16
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HT21
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
Ground reference
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 600V
This instrument can perform only AC sinusoidal voltage measurements
You must comply with the usual safety regulations aimed at protecting you against the
dangerous electric current and protecting the instrument against an incorrect operation
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 battery is 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
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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
EN 61010-1: 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
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2. GENERAL DESCRIPTION
The HT21 meter performs, in completely Autorange, the herewith measurements:
DC Voltage
AC sine voltage
Resistance and Continuity test
Capacitance
Frequency
Duty cycle
Diode test
All selectable by means of a 5 position rotary selector (including OFF position). Also are
available the HOLD/ key to hold the displayed value and enable/disable backlight
feature, the Hz% key for manual selection of frequency and duty cycle measurements, the
REL key for Relative measures and the MODE key for selection of different features which
are common to the same position of rotary selector. 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 30 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 1x9V battery type IEC 1604 NEDA 6F22. When battery is
low, a “ ” low battery indication is displayed. To replace/insert battery 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.
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4. OPERATING INSTRUCTIONS
4.1. INSTRUMENT DESCRIPTION
4.1.1. Front panel description
LEGEND:
1. LCD
2. Rotary selector
3. COM input jack
4. VHz%
5. MODE key
6. Hz% key
7. HOLD/
8. REL key
9. Battery cover
CAP input jack
key
Fig. 1: Instrument description
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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. By pressing the key at least 1 second the enable/disable of backlight feature
can be performed. This feature is active for any position of rotary selector.
4.2.2. Hz% key
By pressing Hz% key the selection of frequency and duty cycle measurements on Hz%
and Hz% positions of selector is performed. The frequency range is different in this two
positions.
4.2.3. REL key
By pressing REL the relative measure is activated. The meter sets the display to zero and
saves the actual value as reference. The “REL” symbol is shown at display. This function
is not active on Hz, duty cycle, continuity test and diode test measurements. Pressing
again the key to exit from this function
4.2.4. MODE key
By pressing MODE key the selection of a double measured functions which are present at
display is performed. In particular this key is active only in / CAP position to select
among Diode Test, Continuity Test and Resistance measurements
4.2.5. Auto power Off
The instrument automatically turns off 30 minutes after last pressure of keys or last
selector rotation. To resume operation turn the selector on OFF and turn on the instrument
again.
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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 . “DC” symbol is displayed
2. Insert the test leads into the jacks, the red plug into VHz% CAP jack and black
plug into COM jack (see Fig. 2)
3. Connect the red and black test leads to the positive and negative poles of the circuit
under test respectively. The voltage value is displayed
4. If the message "O.L" is displayed the higher range is reached
5. The symbol "-" on the instrument display indicates that voltage has opposite direction
with regard to the connection of Fig. 2
6. For HOLD function and Relative measurement please refer to § 4.2
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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 Hz%. “AC” symbol is displayed
2. Insert the test leads into the jacks, the red plug into VHz% CAP jack and black
plug into COM jack (see Fig. 3)
3. Connect the test leads to the circuit under test; the voltage value is displayed
4. If the message "O.L" is displayed the higher range is reached
5. Pressing the Hz% key until the symbols “Hz” or “%” are shown at display to meaning
the readings of frequency or duty cycle associated to voltage AC value
6. For HOLD function and Relative measurement please refer to § 4.2
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4.3.3. Resistance and Continuity Test measurements
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 and continuity test measurements
1. Switch on CAP. “” symbol is displayed
2. Insert the test leads into the jacks, the red plug into VHz% CAP jack and black
plug into COM jack (see Fig. 4)
3. Connect the test leads to the circuit under test. The resistance value is displayed
4. If the message "O.L" is displayed the higher range is reached
5. Pressing the MODE key until the symbol is shown at display to meaning the
Continuity test and connect the meter as resistance measurement. Buzzer emits sound
if the measured resistance value is <150
6. For HOLD function please refer to § 4.2
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4.3.4. Diode test
CAUTION
Before taking diode test 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 CAP
2. Pressing the MODE key until the symbol is shown at display to meaning the diode
test
3. Insert the test leads into the jacks, the red plug into VHz% CAP jack and black
plug into COM jack (see Fig. 5)
4. 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
5. If the threshold voltage value is 0V the diode P-N junction is shorted circuit
6. If the message "O.L" is displayed the diode terminals are reversed, the diode P-N
junction is damaged
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4.3.5. Frequency and Duty Cycle measurements
CAUTION
The maximum input for AC voltage is 250V. Do not attempt to measure
higher voltages to avoid electrical shocks or damages to the instrument.
Fig. 6: Using the instrument for frequency and duty cycle measurements
1. Switch on Hz%. “Hz” symbol is displayed
2. Insert the test leads into the jacks, the red plug into VHz%
CAP jack and black
plug into COM jack (see Fig. 6)
3. Connect the test leads to the circuit under test. The frequency value, with kHz or MHz
units, is displayed
4. If the message "O.L" is displayed the higher range is reached
5. Pressing the Hz% key until the “%” symbol is shown at display to meaning the Duty
Cycle test and connect the meter as frequency measurement. The measured value is
displayed
6. For HOLD function please refer to § 4.2
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4.3.6. Capacitance measurement
CAUTION
Before taking capacitance measurement in circuit remove power from the
circuit being tested and discharge all capacitors. Connect the test capacitor
to the inputs respecting the polarity connections when required.
Fig. 7: Using the instrument for capacitance measurement
1. Switch on CAP
2. Pressing the MODE key until the “nF” symbol is shown at display to meaning the
capacitance measurement
3. Insert the test leads into the jacks, the red plug into VHz% CAP jack and black
plug into COM jack (see Fig. 7)
4. Press the REL key before start the measurement
5. Connect the red and black test clamps to the capacitor terminals respecting if
necessary the proper polarities. The capacitance value is shown on display
6. If the message "O.L" is displayed the higher range is reached
7. For HOLD function and Relative measurement please refer to § 4.2
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HT21
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 (refer to § 6.1.2) is displayed the battery is to be
replaced.
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 § 6.1.2) 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
CAUTION: this symbol indicates that equipment, the battery and its accessories
shall be subject to a separate collection and correct disposal.
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6. TECHNICAL SPECIFICATIONS
6.1. TECHNICAL FEATURES
The accuracy is calculated as [%reading + (number of digits)*resolution]. It is referred to
the following environmental conditions: temperature 18°C28°C (64°F82°F), <70%RH
DC Voltage (Autorange)
Range Resolution Accuracy Input impedance Overload protection
4.000V 0.001V
40.00V 0.01V
400.0V 0.1V
600V 1V
AC Voltage (Autorange except for 400mV range)
Range Resolution
4.000V 0.001V
40.00V 0.01V
400.0V 0.1V
600V 1V
Frequency range: 50Hz 400Hz
Resistance (Autorange)
Range Resolution Accuracy Overload protection
400.0 0.1 (1.2%rdg + 4dgt)
4.000k 0.001k (1.0%rdg + 2dgt)
40.00k 0.01k
400.0k 0.1k
4.000M 0.001M
40.00M 0.01M (2.0%rdg + 3dgt)
Diode Test
Feature Resolution Accuracy Max open voltage Overload protection
1mV
Continuity test
Feature Buzzer Test current Overload protection
Frequency (Autorange)
Range Resolution Accuracy Sensitivity Overload protection
5.000Hz 0.001Hz
50.00Hz 0.01Hz
500.0Hz 0.1Hz
5.000kHz 10Hz
50.00kHz 10Hz
500.0kHz 100Hz
5.000MHz 1kHz
10.00MHz 10kHz
(1.2%rdg+2dgt)
(1.5%rdg+2dgt)
Accuracy
(50 400Hz)
(1.2%rdg+4dgt)
(1.5%rdg+3dgt)
(2.0%rdg+4dgt)
(1.2%rdg + 2dgt)
(10%rdg + 5dgt)
<150
(1.5%rdg + 5dgt)
(1.2%rdg + 3dgt)
(1.5%rdg + 4dgt)
7.8M
Input impedance Overload protection
7.8M
250VDC/ACrms
circa 1.5VDC 250VDC/ACrms
<0.3mA 250VDC/ACrms
>8Vrms 250VDC/ACrms
600VDC/ACrms
600VDC/ACrms
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Duty cycle (Autorange)
Range Resolution Accuracy Sensibilità Overload protection
0.1%-99% 0.1%
100s< pulse width <100ms ; Frequency range: 5Hz 150kHz
(1.2%rdg + 2dgt)
>8Vrms 250VDC/ACrms
Capacitance (Autorange)
Range Resolution Accuracy Overload protection
40.00nF 0.01nF
400.0nF 0.1nF
4.000F 0.001F
40.00F 0.01F
100.0F 0.1F (5.0%rdg +5dgt)
(5.0%rdg + 7dgt)
(3.0%rdg + 5dgt)
250VDC/ACrms
6.1.1. Safety
The instrument complies with: IEC/EN61010-1
Insulation: double insulation
Pollution degree: 2
Measurement category: CAT III 600V
Max height of use: 2000m (6.562 ft)
6.1.2. General data
Mechanical characteristics
Dimensions (LxWxH): 138 x 68 x 37mm ; 5.4 x 2.7 x 1.5 inches
Weight (including battery): 210g (7 ounces)
Power supply
Battery type: 1x9V battery NEDA 1604 IEC 6F22
Indication of low battery: symbol “ ” is displayed
Auto Power OFF: after 30 minutes of idleness
Display
Specifications: 4 LCD, 4000 points + symbol and decimal point
Sample rate: 2times/s
6.2. ENVIRONMENT
6.2.1. Environmental conditions
Reference temperature: 18°C 28°C ; (64°F 82°F)
Working temperature: 0°C ÷ 50°C ; (32°F 22°F)
Relative humidity: <70%HR
Storage temperature: -20°C÷ 60°C ; (-4°F 140°F)
Storage humidity: <80%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
HT21 meter
Test leads - Cod. KIT4000A
Battery
Carrying case
User manual
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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
Faults due to adaptation to a particular application not provided for by the definition of
the equipment or by the instruction manual
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 non original packaging will be charged
anyhow to the customer.
The manufacturer will not be responsible for any damage to persons or things.
EN - 16
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