HT HT21 User manual

Copyright HT ITALIA 2010 Release EN 1.01 - 19/01/2011
ENGLISH
User manual

HT21
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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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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. VHz% CAP input jack
5. MODE key
6. Hz% key
7. HOLD/ key
8. REL key
9. Battery cover
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 VHz% 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 VHz% 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 VHz% 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