HT HT7 User manual

Copyright HT ITALIA 2014 Release EN 1.05 - 21/03/2019
ENGLISH
User manual

HT7
EN - 1
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. 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
4.2. Description of symbols at display.....................................................................................5
4.3. Initial autotest..................................................................................................................5
4.4. DC Voltage measurement ...............................................................................................6
4.5. AC Voltage measurement................................................................................................7
4.6. AC Voltage measurement with low input impedance.......................................................8
4.7. 1-wire AC Voltage Detection (polarity).............................................................................9
4.8. Phase sequence indication............................................................................................10
4.9. Continuity test................................................................................................................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 characteristics ...............................................................................................13
6.1.1. Electrical characteristics .......................................................................................................13
6.1.2. Reference guidelines............................................................................................................13
6.1.3. General specifications...........................................................................................................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. Service..........................................................................................................................15

HT7
EN - 2
1. SAFETY PRECAUTIONS AND PROCEDURES
This instrument complies with IEC/EN61010-1 relative 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 measuring in humid or wet places.
Make sure that humidity is within the limits indicated in section “environmental
conditions”.
Avoid measuring in presence of explosive gas, combustible gas, steam or excessive
dust.
Do not touch exposed metal (conductive) parts such as test lead ends, sockets, fixing
objects, circuits etc.
Avoid measuring if you note anomalous conditions such as breakages, deformations,
fractures, strange substances, blind display etc.
Avoid measuring voltages higher than 20V as you may risk 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 electrical shocks
Double insulated instrument
AC voltage
DC voltage
1.1. PRELIMINARY
This instrument has been designed for use in environments with pollution degree 2.
It can be used for VOLTAGE measurements on installations of CAT IV 600V or CAT III
1000V.
When using the instrument always respect the usual safety regulations aimed at
protecting you against dangerous electric currents as well as the instrument against
incorrect operations.
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 § 6.2.1.
Make sure that batteries are properly installed.

HT7
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 the instrument is connected to circuits never touch an unused terminal.
When measuring resistors do not add any voltage. Although there is a protection
circuit, excessive voltage would still cause malfunction.
1.3. AFTER USE
If you expect not to use the instrument for a long period remove batteries.
1.4. OVERVOLTAGE CATEGORIES - DEFINITIONS
IEC/EN61010-1 (Safety requirements for electrical equipment for measurement, control
and laboratory use, Part 1: General requirements) defines what a measurement category
(usually called “overvoltage category”) is. At § 6.7.4: Measuring circuits it quotes:
(OMISSIS)
Circuits are divided into the following measurement categories:
Measurement category IV is for measurements performed at the source of low
voltage installations.
Examples are electricity instruments and measurements on primary overcurrent
protection devices and ripple control units
Measurement category III is for measurements performed in the building installations.
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 installations.
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 withstanding capability of
the equipment is made known to the user.

HT7
EN - 4
2. GENERAL DESCRIPTION
HT7 performs the following measurements:
DC voltage with 2-wire method
AC voltage with 2-wire method
AC voltage with 1-wire method (polarity detection)
Phase sequence indication
Continuity test with buzzer
Voltage measurement with low impedance input
The measure is displayed with indication of measurement unit both in numerical mode and
as bargraph. A white LED enabled by key is also available to illuminate dark
environments.
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 under perfect
conditions. Notwithstanding we suggest you to check it rapidly (any damage may have
occurred during transport).
Make sure that all standard accessories mentioned in § 6.3 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 powered by 2x1.5V alkaline batteries type AAA LR03. When batteries
are low, a low battery indication “ ”is displayed. To replace batteries follow the
instructions of § 5.2
3.3. CALIBRATION
The instrument complies with the technical specifications contained in this manual.
Considering its extremely friendly use, the instrument does not need any calibration.
3.4. STORAGE
After a period of storage under extreme environmental conditions exceeding the limits
mentioned in § 6.2.1, let the instrument restore normal measuring conditions before use.

HT7
EN - 5
4. OPERATING INSTRUCTIONS
4.1. INSTRUMENT DESCRIPTION
CAPTION:
1. L1 detachable probe
2. L2 fixed probe
3. White LED illuminator
4. LCD display
5. Voltage measurements
warning LED
6. Low impedance test LED
7. Continuity test LED
8. Low impedance switch (L2)
9. key to activate white LED
illuminator
10.Battery cover
11.Low impedance switch (L1)
Fig. 1: Instrument description
4.2. DESCRIPTION OF SYMBOLS AT DISPLAY
The following symbols can be displayed on HT7:
Symbol Description
DC
DC voltage measurement
AC
AC voltage measurement
Negative polarity on DC voltage measurement
This symbol is lighted up whenever the voltage between the probes
exceeds 50V, even if the batteries are low or have been removed
Continuity test
Clockwise phase sequence
Counterclockwise phase sequence
Detection voltage necessary to perform measurements
Low battery indication
4.3. INITIAL AUTOTEST
Before start any measurements perform the following checks:
Use the instrument on a known voltage source.
The " " symbol is lighted up whenever the voltage between the probes exceeds 50V,
even if the batteries are low or have been removed.
Short the L1 and L2 probes. The indicator lights, the buzzer sounds and the LEDs for
the continuity test light up. The LEDs for the low impedance test and the single-phase
voltage do not light up.

HT7
EN - 6
4.4. DC VOLTAGE MEASUREMENT
CAUTION

The maximum input for DC voltage is 690V. Do not measure higher
voltages to avoid risks of electrical shocks or serious damages to the
instrument.
symbol is lighted up whenever the voltage between the probes
exceeds 50V, even if the batteries are low or have been removed.
Fig. 2: DC voltage measurement
1. Perform the preliminary Autotest (see § 4.3).
2. Connect the L1 and L2 probes to the object
under test (see Fig. 2)
3. The instrument turns automatically on and the
measured DC voltage value is displayed both
in numerical and bargraph modes. DC symbol
is displayed. Always keep the instrument in
vertical position for an optimal display reading.
4. The symbol "-", if displayed, indicates that the
measured voltage is negative.
5. The instrument turns automatically off as soon
as the probes are disconnected from the object
under test. If the measured voltage is lower
than 4.5V DC the instrument turns
automatically off.
6. Press the key to switch on the white LED
illuminator to perform measurements in dark
environments.

HT7
EN - 7
4.5. AC VOLTAGE MEASUREMENT
CAUTION

The maximum input for AC voltage is 690V. Do not measure higher
voltages to avoid risks of electrical shocks or serious damages to the
instrument.
symbol is lighted up whenever the voltage between the probes
exceeds 50V, even if the batteries are low or have been removed.
Fig. 3: AC voltage measurement
1. Perform the preliminary Autotest (see § 4.3)
2. Connect the L1 and L2 probes to the object
under test (see Fig. 3). The measurement is
performed only when probes are in contact
to live conductors.
3. The instrument turns automatically on and the
measured AC voltage value is displayed both
in numerical and bargraph modes. AC symbol
is displayed. Always keep the instrument in
vertical position for an optimal display
reading.
4. The symbol is lighted up for AC voltage
measurements from 100V to 690V, 50/60Hz.
5. The instrument turns automatically off as
soon as the probes are disconnected from the
object under test. If the measured voltage is
lower than 3.0V AC the instrument turns
automatically off.
6. While taking measurements in single-phase
installations, the symbols or can be
displayed. This is not a malfunction.
7. Press the key to switch on the white LED
illuminator to perform measurements in dark
environments.

HT7
EN - 8
4.6. AC VOLTAGE MEASUREMENT WITH LOW INPUT IMPEDANCE
CAUTION

The maximum input for AC voltage is 690V. Do not measure higher
voltages to avoid risks of electrical shocks or serious damages to the
instrument.
symbol is lighted up whenever the voltage between the probes
exceeds 50V, even if the batteries are low or have been removed.
This function is particularly useful for testing installations. Thanks to the low input
impedance, voltage due to stray capacitance coupling is nulled. The reading shows the
voltage applied. Similarly, measuring line to earth voltage (VL-PE) may trigger residual
current circuit breakers (RCD). This measuring procedure can be used for
measurements above 12V.
Fig. 4: AC voltage measurement with
low impedance
1. Perform the preliminary Autotest (see § 4.3)
2. Connect the L1 and L2 probes to the object
under test (see Fig. 3). The measurement is
performed only when probes are in contact
to live conductors.
3. The instrument turns automatically on and the
measured AC voltage value is displayed both
in numerical and bargraph modes. AC symbol
is displayed. Always keep the instrument in
vertical position for an optimal display
reading.
4. The symbol is lighted up for AC voltage
measurements from 100V to 690V, 50/60Hz.
5. Press the two switches (see Fig. 1 part 8
and 11) simultaneously. The applied
voltage is displayed on the LCD.
6. The low impedance LED indicates the low
input impedance voltage measurement
(load connection).
7. Press the key to switch on the white LED
illuminator to perform measurements in dark
environments.
CAUTION

The maximum allowed use of low input impedance measurement is 5
seconds for voltages up to 250V and 3 seconds for voltages up to 690V.
Afterwards, please wait 10 minutes before taking further measurements.
The single-wire test is not suitable to measure voltage. For this purpose,
the two-wire voltage testing is necessary.

HT7
EN - 9
4.7. 1-WIRE AC VOLTAGE DETECTION (POLARITY)
CAUTION

The maximum input for AC voltage is 690V. Do not measure higher
voltages to avoid risks of electrical shocks or serious damages to the
instrument.
The 1-wire AC voltage mode should be used as a quick voltage
detection test with no voltage value displaying.
symbol is lighted up whenever the voltage between the probes
exceeds 50V, even if the batteries are low or have been removed.
Fig. 5: 1-wire AC voltage detection
1. Perform the preliminary Autotest (see § 4.3).
2. Connect the L2 probe to the object under
test (see Fig. 5). The measurement is
performed only when probe is in contact
to live conductors.
3. The instrument turns automatically on along
with LEDs and for AC voltage
detected from 100V to 690V, 50/60Hz. The
display and bargraph values are not
significant in this test.
4. The instrument turns automatically off as
soon as the measured voltage is lower than
100V AC.
5. While taking measurements in single-phase
installations, the symbols or can be
displayed. This is not a malfunction.
6. Press the key to switch on the white
LED illuminator to perform measurements in
dark environments.

HT7
EN - 10
4.8. PHASE SEQUENCE INDICATION
CAUTION

The maximum input for AC voltage is 690V. Do not measure higher
voltages to avoid risks of electrical shocks or serious damages to the
instrument.
symbol is lighted up whenever the voltage between the probes
exceeds 50V, even if the batteries are low or have been removed.
Fig. 6: Phase sequence test
1. Perform the preliminary Autotest (see § 4.3).
2. Connect the L1 probe to phase 1 and the L2
probe to phase 2 of the three-phase system
under test (see Fig. 6). The measurement is
performed only when probes are in
contact to live conductors.
3. The instrument turns automatically on and
the measured AC voltage value is displayed
both in numerical and bargraph modes.
4. AC symbol is displayed. LEDs and
are lighted up for AC voltage measurements
from 100V to 690V, 50/60Hz.
5. symbol (clockwise) and symbol
(counterclockwise) are displayed according
to the phase sequence detected.
6. Connect the L1 probe to phase 2 and the L2
probe to phase 3 of the three-phase system
under test. symbol (clockwise) and
symbol (counterclockwise) are displayed
according to the phase sequence detected.
7. Connect the L1 probe to phase 2 and the L2
probe to phase 3 of the three-phase system
under test. symbol (clockwise) and
symbol (counterclockwise) are displayed
according to the phase sequence detected.
8. Press the key to switch on the white
LED illuminator to perform measurements in
dark environments.

HT7
EN - 11
4.9. CONTINUITY TEST
CAUTION
Before taking the continuity test, disconnect the circuit under test from any
power source and discharge all capacitors.
Fig. 7: Continuity test
1. Perform the preliminary Autotest (see § 4.3).
2. Connect the L1 and L2 probes to the object
under test (see Fig. 7)
3. Continuity test is active for resistance
<200k. The instrument turns automatically
on along with LED and the buzzer
indicating a positive test. The display and
bargraph values are not significant in this
test and do not indicate the resistance value
of the object under test.
4. The instrument automatically turns off when
the probes are separated from the object
under test or the applied voltage is lower
than 3V DC.
5. Press the key to switch on the white
LED illuminator to perform measurements in
dark environments.

HT7
EN - 12
5. MAINTENANCE
5.1. GENERAL INFORMATION
This instrument is a precision device. Whether in use or in storage, please do not exceed
the specification requirements to avoid possible damages or dangers. Do not place this
instrument at high temperatures or humidity, or expose it to direct sunlight. Be sure to turn
off the instrument after use. If you expect not to use the instrument for a long time, remove
the batteries in order to avoid leakages of battery liquid that would damage the internal
parts.
5.2. BATTERY REPLACEMENT
When the display shows the low battery symbol “ ” the batteries have to be replaced.
CAUTION
Only expert and trained technicians should perform this operation. Before
carrying out this operation, make sure you have disconnected all test leads
from any energized circuit to avoid risks of electrical shock.
Fig. 8: Battery replacement
1. Unscrew the screw on the bottom of the
instrument and remove the battery cover.
2. Remove the batteries from the battery
compartment.
3. Insert new batteries of the same kind (see §
6.1.3) respecting polarity signs (see Fig. 8).
4. Restore the battery compartment cover into
place and fasten it by mean of the relevant
screw.
5. To preserve the environment do not throw
used batteries. Dispose used batteries
properly.
5.3. CLEANING
To clean the instrument use a soft dry cloth. Never use wet cloths, solvents, water, etc.
5.4. END OF LIFE
CAUTION: this symbol on the instrument indicates that the equipment and its
accessories must be collected separately and correctly disposed of.

HT7
EN - 13
6. TECHNICAL SPECIFICATIONS
6.1. TECHNICAL CHARACTERISTICS
Accuracy is indicated as [%reading + (no. of digits) * resolution] at 23°C±5°C, <70%RH
AC/DC Voltage
Range
Resolution
Accuracy
Input impedance
Overloadprotection
6, 12, 24, 50, 120,
230, 400, 690V 1V

(1.0

rdg+3dgt)
(DC voltage) 1M690VAC/DC

(1.5

rdg+5dgt)
(AC voltage)
Max output current: <1mA (400VAC); <1.5mA (690VDC)
Detection AC/DC voltage: automatic
Measuring range selection: automatic
Frequency range: 50/60Hz
Minimum detected voltage: ≥3V AC/DC
AC Voltage with low internal impedance
Range
Resolution
Measuring time
Input impedance
Overloadprotection
12 230V 1V max 5s < 250V < 6k3s <400VAC ,
690VDC
Max output current: Is ≤200mA @690V, max 30s (ca. 48mA @ 230V)
Detection AC voltage: automatic from 12V
Measuring range selection: automatic
Frequency range: 50/60Hz
Minimum detected voltage: 12VAC
1-wire AC voltage detection (polarity)
Voltage range: 100 690V AC
Frequency range: 50/60Hz
Continuity test
Range
Buzzer
Testcurrent
Overloadprotection
<200kΩ<1

A 690VDC/400VAC
Phase sequence indication
Voltage range: 100 400VAC
Frequency range: 50/60Hz
Measurement method: 2-wire with contact to live parts
6.1.1. Electrical characteristics
Conversion: average value
Sampling frequency: 2-3 times for second
6.1.2. Reference guidelines
Safety: IEC/EN61010-1
Insulation: double insulation
Pollution degree: 2
Measurement category: CAT III 1000V, CAT IV 600V
Max height of use: 2000m (6561ft)

HT7
EN - 14
6.1.3. General specifications
Mechanical characteristics
Dimensions (L x W x H): 240 x 78 x 40mm (9.4 x 3.1 x 1.6in)
Weight (including batteries): 240g (7.7ounces)
Power supply
Battery type: 2x1.5V batteries type AAA LR03
Indication of low batteries: " "is displayed
Auto power off / on fixed
Display
Type: 3½ digits LCD, max. 1999 counts + sign,
bargraph and backlight
6.2. ENVIRONMENT
6.2.1. Environmental conditions
Reference temperature of calibration: 23 ± 5°C (73 ± 41°F)
Operating temperature: -10 ÷ 55°C (14 ÷ 131°F)
Allowable relative humidity: <85%RH
Storage temperature: -10 ÷ 60°C (14 ÷ 140°F)
Storage humidity: <85%RH
This instrument complies with the
European Directive on low voltage
2006/95/CE
(LVD) and with EMC 2004/108/CE
6.3. ACCESSORIES
6.3.1. Standard accessories
Plastic protection of metal probes
4mm metal sleeves with internal thread, 2x
Batteries, 2x 1,5V AAA
User manual
6.3.2. Optional accessories
Carrying bag B71

HT7
EN - 15
7. SERVICE
7.1. WARRANTY CONDITIONS
This instrument is guaranteed for one year 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 warranty shall not apply to:
Accessories and battery are not included in warranty.
Repairs following unsuitable use of the equipment or by combining the latter with
incompatible equipment.
Repairs resulting from a not correct shipping.
Repairs resulting from servicing carried out by a person not approved by the company.
Modifications to the equipment without explicit authorization from our technical
department.
Adaptation to a particular application not provided for by the definition of the equipment
or by the instruction manual.
The content of this manual cannot be reproduced in any form without the manufacturer’s
authorization.
Our products are patented and our trademarks are registered. The manufacturer
reserves the right to make changes in the specifications and prices if this is due to
improvements in technology.
7.2. SERVICE
If the instrument does not operate properly, before contacting the After-sales Service,
please check the conditions of batteries and cables and replace them, if necessary. Should
the instrument still operate improperly, check that the product is operated according to the
instructions given in this manual. Should the instrument be returned to the After-sales
Service or to a Dealer, transport will be at the Customer's charge. However, shipment will
be agreed in advance. A report will always be enclosed to a shipment, stating the reasons
for the products return. Only use original packaging for shipment; any damage due to the
use of non-original packaging material will be charged to the Customer.