HT 1009740, User Manual

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HT7
EN - 3
1.3. AFTER USE
If you expect not to use the instrument for a long period remove batteries.
1.4. OVERVOLTAGE CATEGORIES - DEFINITIONS
IEC/EN61010-1 (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 § 6.7.4: Measuring circuits it quotes:
(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 instruments and measurements on primary overcurrent
protection devices and ripple control units

Measurement category III is for measurements performed in the building installations.
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 installations.
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 withstanding capability of
the equipment is made known to the user.