During Use; After Use; Measuring (Overvoltage) Categories Definitions - Refco X-475 Instructions

1.2 During use

improper use may damage the instrument
An
and/or its components or injure the operator.
•
When changing the range, first disconnect the test leads from the circuit under test in order to
avoid any accident.
•
When the instrument is connected to measuring circuits never touch any unused terminal.
•
When measuring resistors do not add any voltage. Although there is a protection circuit,
excessive voltage could cause malfunctioning.
•
If during measurement the displayed values remain constant check whether the HOLD function
is active.

1.3 After use

•
After using the instrument turn it off.
•
If you expect not to use the instrument for a long period remove the battery to avoid leakages
of battery liquids which may damage its inner components.

1.4 Measuring (overvoltage) categories definitions

EN 61010-1: Safety requirements for electrical equipment for measurement, control and laboratory
use, Part 1: General requirements, gives a definition of measuring category, usually called
overvoltage category. Paragraph 6.7.4: Measuring circuits:
(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.
WARNING
EN-3