HT Instruments HT4011 Manual De Instrucciones página 27

1.2. DURING USE
Please carefully read the following recommendations and instructions:
Failure to comply with the Caution notes 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 under test, do not touch any unused
terminal.
• Avoid measuring resistance if external voltages are present. Even if the instrument is
protected, excessive voltage could cause a malfunction of the clamp.
• When measuring current with the clamp jaws, first remove the test leads from the
instruments input jacks.
• During current measurement, any other current near the clamp may affect
measurement precision.
• When measuring current, always put the conductor as near 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 being measured remain
unchanged, check if the HOLD function is enabled.
1.3. AFTER USE
• When measurement is complete, switch OFF the instrument.
• If you expect not to use the instrument for a long period, remove the battery.
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 what measurement
category is. § 6.7.4: Measured circuits, reads:
(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 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 installation.
• Measurement category II is for measurements performed on circuits directly
connected to the low-voltage installation.
Examples are measurements on household appliances 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.
CAUTION
EN – 3
HT4011