HT instruments XL422 - Manual (Page 4)

XL421 - XL422
1.2 DURING USE
Carefully read the following recommendations and instructions:
WARNING
Non compliance with warnings and/or instructions may cause damage to
the tester or its components or injure the operator.
) During a current measurement keep the clamp as far as possible from cables not
involved in measurement.
) During a current measurement keep the cable under test in the very middle of the jaws.
1.3 AFTER
USE
) If you expect not to use the instrument for a long period of time remove the batteries
and strictly follow the indications at paragraph 9.2.
1.4 OVERVOLTAGE
CATEGORIES - DEFINITIONS
EN 61010-1 (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 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 low
voltage installations.
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.
EN - 3