2.16 SCHALTGERÄTE Wissenswertes von A-Z Know How from A - Z Group switch The group switch is a sub-category of step switches. Whereas step switches make and break contacts separately per step, group switches allow maintaining the make for several switch steps. E.g. the light-bands in production halls are switched according to the illumination situation. IP Rating Relative to suitability for various ambient conditions electrical devices are classified in different degrees of protection, so-called IP-codes. The abbreviation IP according to DIN stands for „International Protection“, anyhow English speaking countries translate it as „Ingress Protection“. They are listed in the DIN EN 60529 with the header „Degrees of protection by means of enclosures (IP-code)“. See table on page 2.23 Isolating function Function for complete power supply disconnection of a facility or part of it, whereas the facility must be completely separated from any source of energy for safety reasons. The position of the main contacts must be clearly and effectively displayed. The switch disconnector must be lockable in the OFF-position according to IEC/EN 60204-1. Increased requirements for actuators stability are based on IEC/EN 60947-3 in order to avoid, that the actuator can be moved to the OFF-position in case of welded contacts. IEC/EN 60947-3; 8.1.7 Line and cable entry points Line and cable entry points in housings and average values for the sealing zones of cable glands. See table on page 2.23 Main switch DIN VDE 0113 part 1 resp. IEC/EN60204-1 is applicable for the safety and electrical equipment of machinery. The application of these normatives serves as well to achieve the safety aims of the EC machinery directive. A manually operated main switch has to be provided for every mains supply. As switch-disconnector it must comply with utilisation category AC-23 and fulfil following requirements: - disconnecting the electric device of the mains, showing a single ON and OFF position each only, clearly marked with 0 and 1. In addition a triggered position is admissible. - visible isolating distance or position indicator showing the OFF position only in case all contacts are opened in fact and a sufficient clearance according to the normatives is achieved. In case the main switch is not used as an emergency-off switch at the same time, red is excluded as its handle colour. Than black or grey are recommended colours. - It has to be lockable in OFF-Position (e.g. by padlocks) - All active conductors have to be disconnected of the mains. In TN net systems it is admissible to separate or not to separate the N-conductor. - The rated breaking capacity has to be sufficient to break the current of the biggest motor in blocked state together with the sum of all operational currents of all other motors/consumers. However, the admitted rated thermal current has not to be exceeded! - The handle of the main switch must be easily accessible and must be situated in a height between 0,6 and 1,9 m of the floor level. Metering switch Colloquially called voltmeter and ammeter selector switches, offered for the most different types of mains networks. The range MERZ offers with switches of series MN covers all possible variations.
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