PMK 880-102-501, Инструкция по эксплуатации

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Measurement
Category III Definition: MEASUREMENT CATEGORY III is applicable to test and measuring
circuits connected to the distribution part of the building’s low-volta-
ge mains installation. To avoid risks caused by the HAZARDS arising
from these higher short-circuit currents, additional insulation and ot-
her provisions are required.
CAT III
Examples: Measurements on distribution boards (including secondary meters),
photovoltaic panels, circuitbreakers, wiring, including cables, bus-
bars, junction boxes, switches, socket-outlets in the fixed installation,
and equipment for industrial use and some other equipment such as
stationary motors with permanent connection to the fixed installation.
Measurement
Category II
Definition: MEASUREMENT CATEGORY II is applicable to test and measuring
circuits connected directly to utilization points (socket outlets and si-
milar points) of the low-voltage mains installation.
Examples: Measurements on MAINS CIRCUITS of household appliances, por-
table tools and similar equipment, and on the consumer side only of
socket-outlets in the fixed installation.
No Measurement
Category
Definition: Many types of test and measuring circuits are not intended not in
CAT II, III or IV to be directly connected to the mains supply. Some of
these measuring circuits are intended for very low energy applicati-
ons, but others of these measuring circuits may experience very high
amounts of available energy because of high short-circuit currents
or high open-circuit voltages. There are no standard transient levels
defined for these circuits. An analysis of the WORKING VOLTAGES,
loop impedances, temporary overvoltages, and transient overvolta-
ges in these circuits is necessary to determine the insulation require-
ments and short-circuit current requirements.
not in CAT II, III or IV
Examples: Thermocouple measuring circuits, high-frequency measuring circuits,
automotive testers, and testers used to characterize the mains instal-
lation before the installation is connected to the mains supply.
IEC Measurement Categories
Definitions and Examples
Measurement
Category IV
Definition: MEASUREMENT CATEGORY IV is applicable to test and measuring
circuits connected at the source of the building’s low-voltage mains ins-
tallation. Due to these high short-circuit currents which can be followed
by a high energy level, measurements made within these locations are
extremely dangerous. Great precautions shall be made to avoid any
chance of a short circuit.
CAT IV
Examples: Measurements on devices installed before the main fuse or circuit
breaker in the building installation.