HT Instruments EQUITEST Manual De Instrucciones página 23

1.3. DEFINITION OF MEASUREMENT CATEGORY
Standard ""IEC/EN61010-1: Safety requirements for electrical
equipment for measurement, control and laboratory use, Part 1:
General requirements" defines what measurement
commonly called overvoltage category, is. § 6.7.4: Measured
circuits, reads: circuits are divided into the following measurement
categories:
•
Measurement category IV is for measurements performed at
the source of a 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 fixed installation, and equipment for
industrial use and some other equipment, for example,
stationary motors
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 standard requires that the transient withstand
capability of the equipment is made known to the user
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