Measurement category
The measurement category specifies the permissible areas of application for measuring and testing devices for electrical equipment and systems (e.g. voltage testers , multimeters , VDE testing devices) for use in the area of low-voltage networks . The classification of the measurement category is determined by IEC 61010-2-030 ( Safety regulations for electrical measuring, control, regulating and laboratory devices Part 2-030: Special regulations for test and measurement circuits ).
The category is of particular importance for the safety of measurements, since low-resistance circuits have higher short-circuit currents and / or disturbances in the form of load switching and other transients must be coped with by the measuring device without endangering the user with electric shocks , fire, sparks or explosions. Due to the low impedance of the public power supply network, short-circuit currents are greatest at the house feed . Within the house system, the maximum short-circuit currents are reduced by the series resistances of the system.
Technically, compliance with the category u. a. ensured by contact protection of plugs and sockets, insulation, sufficient air and creepage distances , strain relief and kink protection of cables as well as sufficient cable cross-sections.
The measurement category is indicated on the measurement devices with Roman numerals. If this information is missing, the device may only be used for category 1 (CAT I) measurements.
The following categories and uses are defined in IEC 61010-2-030:
| CAT I | Measurements on circuits that have no direct connection to the grid (battery operation), e.g. B. Protection class 3 devices (operation with safety extra-low voltage), battery-operated devices, conventional car electrics. |
|---|---|
| CAT II | Measurements on circuits that have a direct connection to the low-voltage network by means of a plug, e.g. B. household appliances, portable electrical appliances. |
| CAT III | Measurements within the building installation (stationary consumers with non-pluggable connections, distributor connections, permanently installed devices in the distributor), e.g. B. Sub-distribution. |
| CAT IV | Measurements at the source of the low voltage installation ( meter , main connection, primary overcurrent protection), e.g. B. meters, low voltage overhead lines, house connection boxes . |
The categories are also divided into the voltage levels 300 V / 600 V / 1000 V.
When testing devices, they are subjected to a test voltage that is significantly higher.
Individual evidence
- ↑ New safety standard IEC 61010-1 since January 1, 2004 .
- ↑ Measurement categories according to IEC 61010-1 (PDF; 4.2 MB); archived under [1] .