HT Instruments HT25N User manual

Copyright HT ITALIA 2017 Release EN 2.01 - 06/09/2017
ENGLISH
User manual

HT25N
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.Storage.............................................................................................................................. 4
4.NOMENCLATURE........................................................................................................5
4.1.Instrument description....................................................................................................... 5
4.2.Description of function keys .............................................................................................. 5
4.2.1.HOLD key................................................................................................................................... 5
4.2.2.Backlight key ......................................................................................................................... 5
5.OPERATING INSTRUCTIONS.....................................................................................6
5.1.DC Voltage measurement................................................................................................. 6
5.2.AC Voltage measurement................................................................................................. 7
5.3.DC Current measurement................................................................................................. 8
5.4.Resistance measurement.................................................................................................. 9
5.5.Continuity test and Diode test ......................................................................................... 10
5.6.Battery test...................................................................................................................... 11
6.MAINTENANCE .........................................................................................................12
6.1.Battery and fuses replacement........................................................................................ 12
6.2.Cleaning.......................................................................................................................... 12
6.3.End of life ........................................................................................................................ 12
7.TECHNICAL SPECIFICATIONS ................................................................................13
7.1.Technical features...........................................................................................................13
7.1.1.Reference standards................................................................................................................ 14
7.1.2.General data............................................................................................................................. 14
7.2.Environment.................................................................................................................... 14
7.2.1.Environmental conditions ......................................................................................................... 14
7.3.Accessories..................................................................................................................... 14
7.3.1.Standard accessories............................................................................................................... 14
8.SERVICE....................................................................................................................15
8.1.Warranty conditions......................................................................................................... 15
8.2.After-sale service............................................................................................................. 15

HT25N
EN - 2
1. SAFETY PRECAUTIONS AND PROCEDURES
This meter is in compliance with IEC/EN61010-1 guideline 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 risk of
electrical shocks.
The following symbols are used on the instrument and in the manual:
CAUTION - refer to the instruction manual - an improper use may damage the
instrument or its components.
Double insulated meter.
AC Voltage
DC Voltage or Current
Ground reference
1.1. PRELIMINARY
This instrument has been designed for use in environments of pollution degree 2.
It can be used for VOLTAGE and DC CURRENT measurements on installations of
CAT III 600V measurement
This instrument is not suitable for measurements of not sine wave voltage.
When using the instrument always respect the usual safety regulations aimed at
protecting you against the dangerous electric currents and protecting the instrument
against incorrect operations.
Only the leads supplied with the instrument guarantee compliance with the safety
standards in force. They must be in good conditions and, if necessary, replaced with
identical ones.
Do not test or connect to any circuit exceeding the specified overload protection.
Do not effect measurements under environmental conditions exceeding the limits
indicated in § 6.2.1
Make sure that batteries are properly 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

HT25N
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.

HT25N
EN - 4
2. GENERAL DESCRIPTION
This instrument performs the below listed measurements:
DC Voltage
AC sine wave Voltage
DC Current
Resistance
Continuity test
Diode test
9V and 1.5V battery test
All function is selectable by means of a rotary selector. In addition there are the HOLD key
to hold the displayed value and the key for activated/disable LCD backlight.
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 § 7.3.1 are included. Should you
have to return back the instrument for any reason please follow the instructions mentioned
in § 8.
3.2. SUPPLY VOLTAGE
The instrument is supplied by 1x9V battery type IEC 6F22. When battery are low, a low
battery indication “ ” is displayed. To replace/insert battery please refer to § 6.1.
3.3. STORAGE
After a period of storage under extreme environmental conditions exceeding the limits
mentioned in § 7.2.1 let the instrument resume normal measuring conditions before using
it.

HT25N
EN - 5
4. NOMENCLATURE
4.1. INSTRUMENT DESCRIPTION
CAPTION:
1. LCD display
2. HOLD key
3. Backlight key
4. Function selector
5. Input terminal 10A
6. Input terminal
VmAA
7. Input terminal COM
Fig. 1: Instrument description
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. Press again HOLD to disable this function and resume normal operation.
4.2.2. Backlight key
By pressing key it’s possible to activate/disabled the backlight function on the display.

HT25N
EN - 6
5. OPERATING INSTRUCTIONS
5.1. 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. Selecting the position 200mV , 2000mV , 20V , 200V or 600V
2. Insert the test leads into the jacks, the red plug into VmAAjack and black plug
into COM jack
3. 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
4. If the message "OL" is displayed select a higher range.
5. The symbol "-" on the instrument display indicates that voltage has opposite direction
with regard to the connection.
6. For HOLD function refer to § 4.2.1

HT25N
EN - 7
5.2. 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. Selecting the position 200Vor 600V
2. Insert the test leads into the jacks, the red plug into VmAAjack and black plug
into COM jack
3. Connect the test leads to the circuit under test (see Fig. 3). The voltage value is
displayed
4. If the message "OL" is displayed select a higher range.
5. For HOLD function refer to § 4.2.1

HT25N
EN - 8
5.3. DC CURRENT MEASUREMENT
CAUTION
The maximum input for DC current is 10A (10A input) or 200mA
(VmAAinput). Do not attempt to measure higher currents to avoid
electrical shocks or damages to the instrument.
Fig. 4: Using the instrument for DC Current measurement
1. Power off the circuit under test
2. Selecting the position 2000A, 20mA , 200mA or 10A
3. Insert the test leads into the jacks, the red plug into 10A jack or VmAAjack
and black plug into COM jack
4. Connect the red and the black plugs in series with the circuit whose current is to be
measured respecting the polarities (see Fig. 4)
5. Energize the circuit under test. The current value will be displayed.
6. The message "OL" means that the detected current exceeds the limits.
7. The symbol "-" on the instrument display indicates that voltage has opposite direction
with regard to the connection.
8. For HOLD function refer to § 4.2.1

HT25N
EN - 9
5.4. RESISTANCE MEASUREMENT
CAUTION
Before taking resistance measurements on the circuit remove power from
the circuit being tested and discharge all capacitors.
Fig. 5: Using the instrument for Resistance measurement
1. Selecting the position 200, 2000, 20k, 200kor 2000k
2. Insert the test leads into the jack, the red plug into VmAAjack and black plug
into COM jack
3. Connect the test leads to the circuit under test (see Fig. 5). The resistance value is
displayed
4. If the message "OL” is displayed a higher range must be selected
5. For HOLD function refer to § 4.2.1

HT25N
EN - 10
5.5. CONTINUITY TEST AND DIODE TEST
CAUTION
Before taking resistance measurements on the circuit remove power from
the circuit being tested and discharge all capacitors.
Fig. 6: Using the instrument for Continuity test and Diode test
1. Selecting the position
2. Insert the test leads into the jacks, the red plug into VmAAjack and black plug
into COM jack
Continuity test
3. Connect the test leads to the circuit under test (see Fig. 6 – left part)
4. The resistance value (just indicative) is displayed and the instrument emits a sound
signal if the resistance value results to be <60
Diode test
5. Connect the test leads to the diode under test observing the proper polarities (see Fig. 6 –
right part)
6. The threshold voltage value of direct polarization, expressed in mV is shown at display
7. If the threshold voltage value is 0V the diode P-N junction is shorted circuit
8. If the message “OL" is displayed the diode terminals are reversed, the diode P-N
junction is damaged

HT25N
EN - 11
5.6. BATTERY TEST
Fig. 7: Using the instrument for Battery test
1. Selecting the position 1.5V (1.5V battery test) or 9V (9V battery test)
2. Insert the test leads into the jacks, the red plug into VmAAjack, and black plug
into COM jack
3. Connect the red and black test leads to the positive and negative poles of the battery
under test respectively (see Fig. 7). The battery voltage value is displayed
4. For HOLD function refer to § 4.2.1

HT25N
EN - 12
6. MAINTENANCE
CAUTION
Only skilled technicians can open the instrument and replace batteries.
Before removing batteries disconnect the test leads from the input
terminals to avoid electrical shocks
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 its inner components
6.1. BATTERY AND FUSES REPLACEMENT
When the low battery indication " " is shown the battery is to be replaced.
Battery replacement
1. Turn off the instrument
2. Disconnect the test leads from the input terminals.
3. Remove the fixing screw from the battery cover and detach it.
4. Remove the battery replacing it with new one of the same type (see § 7.1.2) respecting
the polarity signs.
5. Replace the battery cover and screw
6. Use the appropriate battery disposal methods for your area.
Fuses replacement
1. Turn OFF the meter and disconnect the test leads from the input terminals
2. Unscrew the four fixing screws of the back holster and remove it
3. Remove the defective fuse and install a new fuse of the same size and rating (see §
7.1.2) Make sure the new fuse is centered in the fuse holder. Re-screw the back
holster
6.2. CLEANING
To clean the instrument use a soft dry cloth. Never use a wet cloth, solvents or water.
6.3. END OF LIFE
CAUTION: this symbol indicates that equipment and its accessories shall be
subject to a separate collection and correct disposal.

HT25N
EN - 13
7. TECHNICAL SPECIFICATIONS
7.1. TECHNICAL FEATURES
Accuracy is calculated as [%rdg + (num. digits*resolution)] at 18°C 28°C, < 75%HR
DC Voltage
Range Resolution Accuracy Input impedance Overload
protection
200.0mV 0.1mV
(0.7%rdg + 3dgt) >1M
200Vrms
2000mV 1mV
600V DC/AC
20.00V 0.01V
200.0V 0.1V (1.0%rdg + 3dgt)
600V 1V
AC Voltage
Range Resolution Accuracy
(5060Hz) Input impedance Overload
protection
200.0V 0.1V (1.5%rdg + 12dgt) >1M600V DC/AC
600V 1V
DC Current
Range Resolution Accuracy Internalvoltagedrop Overload
protection
2000A 1A
(1.5%rdg + 3dgt) 200mV
Fast fuse
200mA / 600V
20.00mA 0.01mA
200.0mA 0.1mA
10.00A 0.01A (2.5%rdg + 2dgt) Fast fuse
10A / 600V
Resistance and Continuity test
Range Resolution Accuracy Buzzer Overload
protection
200.00.1
(1.2%rdg + 4dgt) <60250Vrms <15sec
20001
20.00k0.01k
200.0k0.1k
2000k1k(1.5%rdg + 2dgt)
Diode test
Function Test current Max open circuit voltage
approx 1mA circa 1.2V
Battery test
Range Resolution Accuracy Test current
1.5V 1mV
(1.5%rdg + 3dgt) 100mA
9V 10mV 6mA

HT25N
EN - 14
7.1.1. Reference standards
Safety: IEC/EN61010-1
EMC: IEC/EN61326-1
Insulation: double insulation
Pollution degree: 2
Measurement category: CAT III 600V
Max height of use: 2000m (6561ft)
7.1.2. General data
Mechanical characteristics
Dimensions (L x W x H): 150 x 70 x 48mm (6 x 3 x 2in)
Weight (including battery): 255g (9 ounces)
Mechanical protection: IP40
Power supply
Battery type: 1x9V battery type NEDA 1604 IEC 6F22
Battery life: ca 30h (backlight ON), ca 130h (backlight OFF)
Low battery indication: symbol " " is displayed
Fuses: F10A/600V, 5 x 20mm (10A input)
F200mA/600V, 5 x 20mm (mAAinput)
Display
Specifications: 3½ LCD with max. reading 2000 counts + sign
and decimal point, backlight
7.2. ENVIRONMENT
7.2.1. Environmental conditions
Reference temperature: 18°C 28°C (64°F ± 82°F)
Working temperature: 0°C ÷ 50°C (32°F ÷ 122°F)
Relative humidity: <70%HR
Storage temperature: -20°C ÷ 60°C (-4°F ÷ 140°F)
Storage humidity: <80%HR
This instrument satisfies the requirements of Low Voltage Directive 2014/35/EU
(LVD) and of EMC Directive 2014/30/EU
This instrument satisfies the requirements of 2011/65/EU (RoHS) directive and
2012/19/EU (WEEE) directive
7.3. ACCESSORIES
7.3.1. Standard accessories
Test leads
User manual
Battery

HT25N
EN - 15
8. SERVICE
8.1. 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 no 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 provided 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 unskilled or
unauthorized personnel.
Instruments for whatever reason modified by the customer himself without explicit
authorization of our Technical Dept.
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.
8.2. 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.