User Manual

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IEC Measurement Categories Definitions and Examples (Clause 6.5.2 ) PHV1000
Measurement Category I Definition: Measurement category I is for measurements
performed on circuits not directly connected to a
mains supply.
Examples: Measurements in circuits not derived from a mains
supply and specially protected ( internal ) circuits
derived from a mains supply. In the latter case,
transient stresses are variable; for that reason requires
that the transient withstand capability of the equipment
is made known to the user.
Measurement Category II Definition: Measurement category II is for measurements
CAT II performed on circuits directly connected to the
low voltage installation.
Examples: Household appliances, portable tools and similar
equipment.
Measurement Category III Definition: Measurement category III is for measurements
CAT III performed in the building installation.
Examples: 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 like for example
stationary motors with permanent connection to the
fixed installation.
Measurement Category IV Definition: Measurement category IV is for measurements
CAT IV performed at the source of the low-voltage installation.
Examples: Electricity meters and measurements on primary over
current protection devices and and ripple control units.