HT HT9020, User Manual

Page: 5 / 52

HT9020
EN - 3
1.2. DURING USE
Please carefully read the following recommendations and instructions:
CAUTION
Failure to comply with the Caution notes and/or Instructions may damage
the instrument and/or its components or be a source of danger for the
operator.

Before activating the switch, remove the conductor from the clamp jaw or disconnect
the test leads from the circuit under test.

When the instrument is connected to the circuit, do not touch any unused terminal.

Keep your hands always under the hand protection. This protection is always located in
a suitable position to guarantee a correct safety distance from possible exposed or live
parts (see Fig. 3)

Avoid measuring resistance if external voltages are present. Even if the instrument is
protected, excessive voltage could cause a malfunction of the clamp.

During current measurement, any other current near the clamp may affect
measurement accuracy.

When measuring current, always put the conductor as close as possible to the middle
of the clamp jaw, to obtain the most accurate reading.

While measuring, if the value or the sign of the quantity under test remain unchanged,
check if the HOLD function is enabled.
1.3. AFTER USE

When measurement is complete, switch
OFF
the instrument.

If the instrument is not to be used for a long time, remove the batteries
1.4. DEFINITION OF MEASUREMENT (OVERVOLTAGE) CATEGORY
Standard IEC/EN61010-1: “Safety requirements for electrical equipment for measurement,
control and laboratory use, Part 1: General requirements” defines measurement category,
commonly called overvoltage category. In § 6.7.4: Measured circuits, circuits are divided
into the following measurement categories:
(OMISSIS)

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 on installations inside
buildings.
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 installations.

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 standard requires that the transient withstand capability of the equipment is made
known to the user.