Ht-instruments HT4010 Manuel d'utilisateur télécharger pdf (Page 25)

HT4010

EN - 4

1.4 MEASURING (OVERVOLTAGE) CATEGORIES DEFINITIONS

The norm IEC/EN61010-1: Safety requirements for electrical equipment for measurement,

control and laboratory use, Part 1: General requirements, defines what measuring

category, usually called overvoltage category, is. On 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

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Ht-instruments HT4010 Manuel d'utilisateur Page 25