HT instruments HT39 User Manual

ENGLISH

User’s manual

© Copyright HT ITALIA 2008 Release EN 1.03 - 04/02/2008

HT37 - HT39

Content:

1. SAFETY PRECAUTIONS AND PROCEDURES..........................................................3

1.1. Preliminary.............................................................................................................3

1.2. During use.............................................................................................................4

1.3. After use................................................................................................................4

1.4. Measuring (overvoltage) categories definitions .....................................................5

2. GENERAL DESCRIPTION...........................................................................................6

2.1. Mean value and TRMS: definition..........................................................................6

2.2. True root mean square value and crest factor: definition.......................................6

3. PREPARATION FOR USE...........................................................................................7

3.1. Initial......................................................................................................................7

3.2. Supply Voltage ......................................................................................................7

3.3. Calibration .............................................................................................................7

3.4. Storage..................................................................................................................7

4. OPERATING INSTRUCTIONS.....................................................................................8

4.1. Instrument Description...........................................................................................8

4.1.1. Front panel................................................................................................................... 8

4.2. FUNCTION Keys...................................................................................................9

4.2.1. MIN MAX...................................................................................................................... 9

4.2.2. PEAK/∆ ........................................................................................................................ 9

4.2.3. RANGE ........................................................................................................................ 9

4.2.4. HOLD........................................................................................................................... 9

4.2.5. RS-232 for connection to PC (HT39 only).................................................................. 10

4.2.6. BACKLIGHT

4.2.7. Disable AutoPowerOFF ............................................................................................. 10

(HT39 only)..................................................................................... 10

4.3. Measurements.....................................................................................................11

4.3.1. DC Voltage measurement.......................................................................................... 11

4.3.2. AC Voltage measurement.......................................................................................... 12

4.3.3. DC Current measurement.......................................................................................... 13

4.3.4. AC Current Measurement.......................................................................................... 14

4.3.5. Frequency measurement........................................................................................... 15

4.3.6. Resistance measurement .......................................................................................... 16

4.3.7. Diode test and continuity test..................................................................................... 17

4.3.8. Capacitance measurement........................................................................................ 18

5. MAINTENANCE..........................................................................................................19

5.1. General Information.............................................................................................19

5.2. Battery Replacement...........................................................................................19

5.3. Fuse Replacement ..............................................................................................20

5.4. Cleaning ..............................................................................................................20

5.5. End of life ............................................................................................................ 20

6. TECHNICAL SPECIFICATIONS................................................................................. 21

6.1. Technical Features..............................................................................................21

6.1.1. Electrical specifications.............................................................................................. 22

6.1.2. Safety......................................................................................................................... 22

6.1.3. General data .............................................................................................................. 23

6.2. Environment ........................................................................................................23

6.2.1. Environmental conditions........................................................................................... 23

6.2.2. EMC and LVD............................................................................................................ 23

6.3. Accessories.........................................................................................................23

7. SERVICE....................................................................................................................24

7.1. Warranty Conditions............................................................................................24

7.2. Service ................................................................................................................ 24

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1. SAFETY PRECAUTIONS AND PROCEDURES

This instrument conforms with safety Standard EN 61010-1 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 shock.

Double insulated meter.

AC voltage or current.
DC voltage or current.

1.1. PRELIMINARY

• This instrument has been designed for use in environments of pollution degree 2.

• It can be used for VOLTAGE and CURRENT measurements on installations of

overvoltage category III 1000V and IV 600V.

• When using the instrument always respect the usual safety regulations aimed at:
♦ Protecting you against the dangerous electric currents.
♦ 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 paragraph 6.2.1.

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• Make sure that batteries are properly installed.

• Before connecting the test probes to the installation, make sure that the function

selector is positioned on the required measurement.

• Make sure that LCD and function selector indicate the same function.

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.

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1.4. MEASURING (OVERVOLTAGE) CATEGORIES DEFINITIONS

The norm EN 61010-1: Safety requirements for electrical equipment for measurement,
control and laboratory use, Part 1: General requirements, defines what measuring
category, usually called overvoltage category, is. On paragraph 6.7.4: Measuring circuits, it
says:

(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

This instrument performs the following measurements:

• DC and AC TRMS Voltage.

• DC and AC TRMS Current.

• Resistance and Continuity test.

• Diode test.

• Frequency.

• Capacitance.

All selectable by means of a 10-position function selector (including OFF position).
FUNCTION keys are also available (see chapter 4.2). An analogical bargraph is also
available. 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 pressure on keys or rotation of selector. To resume
normal operation turn the selector on OFF and switch it on again.

2.1. MEAN VALUE AND TRMS: DEFINITION

Safety testers for AC quantities are divided in two big families:

• MEAN VALUE instruments, measuring only the value of the wave at the fundamental

frequency (50 or 60 Hz).

• TRUE ROOT MEAN SQUARE (or “TRMS”) instruments, measuring the true root mean

square value of the quantity under test.
In presence of a perfectly sinusoidal wave, both families provide identical results. While in
presence of distorted waves, readings are different. Mean value instruments provide only
the value of the fundamental wave while TRMS instruments provide the value of the entire
wave, including harmonics (within the passband of the instrument). Accordingly, if the
same quantity is measured with both kinds of instruments, the measured values are
identical only if the wave is purely sinusoidal. Should it be distorted, TRMS instruments
provide higher values than MEAN VALUE instruments.

2.2. TRUE ROOT MEAN SQUARE VALUE AND CREST FACTOR: DEFINITION

The effective current value is defined as follows: “In an interval of time equivalent to a
period, an alternate current with effective value having an intensity of 1A, by passing on a
resistor, disperses the same energy which would be dispersed in the same period of time
by a direct current having an intensity of 1A”. From this definition comes the numerical

+Tt

0

1

expression: G=

T

The Crest Factor is defined as the ratio between the Peak Value of a signal and its
effective value: CF (G)=

for a purely sinusoidal wave it’s worth
assumes higher values as long as the wave distortion is higher.

2

dttg

)(

∫

t

0

The effective value is indicated as RMS (root mean square).

G

p

. This value varies according to the waveform of the signal,

G

RMS

2

=1.41. In presence of distortions the Crest Factor

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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 paragraph 6.3 are included.
Should you have to return back the instrument for any reason please follow the

instructions mentioned in paragraph 7.

3.2. SUPPLY VOLTAGE

The instrument is powered by batteries mod. 9V NEDA1604, JIS006P, IEC6F22 included
in the packaging. Battery life is approx. 300 hours.

When batteries are low the symbol "
instructions indicated in paragraph 5.2.

3.3. CALIBRATION

The instrument complies with the technical specifications contained in this manual and
such compliance is guaranteed for 12 months.

3.4. STORAGE

After a period of storage in extreme environmental conditions exceeding the limits
mentioned in paragraph 6.2.1 let the instrument resume normal operating conditions
before using it.

" is displayed. To replace/insert batteries follow the

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4. OPERATING INSTRUCTIONS

4.1. INSTRUMENT DESCRIPTION

4.1.1. Front panel

LEGEND:

1. LCD display.

2. Functions keys (RS-232
and

keys for HT39

only).

3. Rotary selector.

4. A input for AC/DC
current measurements.

5.

HzVΩµA input for

other measurements.

6. COM input.

Fig. 1: Instrument description

EN - 7