Cat I; Measurement Categories Cat - Hameg Instruments HM5510 Manual

It is prohibited to disconnect the safety earth eit-
her within the instrument or externally!
– Before operation check whether the mains voltage cor-
responds to the mains voltage selector setting of the
instrument.
– This instrument may only be opened by qualifi ed person-
nel.
– Prior to opening the instrumjent must be disconnected
from the mains and all other signals.
In any of the following cases do not use the instrument any
more and store it in a secure place:
– Visible damage
– Damaged mains cord
– Damaged fuse holder
– Loose parts inside the instrument
– Does not function any more.
– After prolonged storage under unfavourable conditions
such as humidity, or in the open.
– Excessive abuse during transport.
Most electron tubes generate gamma rays. With
this instrument the ion dose remains far below the
allowed limit of 36 pA/kg.
This measuring instrument must only be used
by personnel familiar with the risks and dangers
associated with the measurement of electrical
signals.
This instrument may only be operated from a
mains outlet conforming to the applicable safety
standards. It is prohibited to disconnect the safety
earth. The mains plug must be inserted prior to
connecting any signals to the instrument.
Overhead lines
CAT IV
Premises Permanently installed
In-house machinery, distribution sites,
installation power conductors, mains
outlets close to the CAT IV
installation
CAT III

CAT I

The following remarks concern only the safety of the user.
Other aspects e.g. the maximum input voltage etc. are cove-
red in the Specifi cations section of this manual and are to be
observed as well.
This measuring instrument is destined for measurements in
circuits which are not connected in any way with the mains,
i.e. battery operated resp. galvanically isolated circuits. Direct
measurements (i.e. without galvanic isolation) in circuits of
measurement categories II, II, and IV are prohibited. Galvanic
isolation is ensured by an isolation transformer of Safety Class
II or a transducer such as a current probe of Safety Class II,
using any of these allows at least indirect measurements. In
any case the measurement category of the transducer must
be checked.

Measurement categories CAT

The measurement categories were created with respect to the
different kind of transients incurred in practice. Transients are
short, fast, and fast-rise changes of voltage or current, they
may be periodic or non-periodic. The amplitudes of transients
increase with decreasing distance from their source.
CAT IV: Measurements at the source of a low voltage supply,
e.g. at electricity meters.
CAT III: Measurements inside a building, e.g. at distribution
sites, power switches, permanently installed mains
outlets, permanently mounted motors etc.
CAT II: Measurements in circuits which are directly con-
nected with the low voltage supply, e.g. household
appliances, portable tools etc.
CAT I: Electronic instruments and circuits which contain
circuit breakers resp. fuses.
Mains outlets for
household appliances,
portable tools, PC,
refrigerator etc.
I m p o r t a n t h i n t s
CAT II
Subject to change without notice
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