HT instruments FULLTEST3 User Manual
Page 6
FULLTEST
3
EN - 5
Do not measure resistance in presence of external voltages; although the instrument is protected,
an excessive voltage may cause malfunctioning.
Do not open the instrument! Dangerous voltages inside!
Connecting one terminal to the test object and working with one probe or holding both probes in
one hand is prohibited.
Use safety probes with protection against contact or with two-hand operation only. Always hold
only one probe in one hand.
It is prohibited to touch the unit under test during the test. If need be, additional measures must be
taken (e.g. cover made of insulating mats) to protect the person performing the test against
inadvertent contact with the unit under test.
1.3. AFTER USE
Disconnect all test leads from the circuit under test and switch off the instrument.
1.4. OVERVOLTAGE CATEGORIES - DEFINITIONS
Standard EN61010-1 (Safety requirements for electrical equipment for measurement, control and
laboratory use, Part 1: General requirements) defines what a measurement category (usually called as
Overvoltage Category) is. At 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.