After Use; Definition Of Measurement (Overvoltage) Category - T.I.S. INSTRUMENTS MFT-PRO Quick Reference Manual

1.2.

AFTER USE


When measurements are completed, switch off the instrument by pressing the ON/OFF key.

If the instrument is not to be used for a long time, follow the instructions for storage described in § 3.4 of
the user manual.
For detailed information, please read the instrument's user manual provided on CD-ROM
before each use.
1.3.

DEFINITION OF MEASUREMENT (OVERVOLTAGE) CATEGORY

Standard "IEC/EN61010-1: Safety requirements for electrical equipment for measurement, control and
laboratory use, Part 1: General requirements" defines what measurement category, 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 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 on installations inside buildings.
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 standard
requires that the transient withstand capability of the equipment is made known to the user.
CAUTION
EN – 3
MFT-PRO
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