Guide Switch Gear Siemens
Introduction This guide covers three subchapters: High voltage substations, Medium voltage substations and Low voltage substations. Low voltage main distribution Low voltage distribution switchgear max. 7 000 A – SIVACON S8 When selecting a low voltage main distribution system, the prerequisite for its efficient sizing is knowing about its use, availability and future options for extension.
The requirements for power distribution are extremely diverse. Normally, frequent switching operations need not be considered in the planning of power distribution for commercial, institutional and industrial building projects, and extensions are generally not to be expected. For these reasons, a performance-optimized technology with high component density can be used.
In these cases, Siemens mainly uses circuit-breaker protected equipment in fixed-mounted design. When planning a power distribution system for a production plant, however, system availability, extendibility, control and the visualization of status information and control functions are important issues related to keeping plant downtimes as short as possible. The use of circuit-breaker protected technology in withdrawable design is important.
Selectivity is also of great importance for reliable power supply. Between these two extremes there is a great design variety that should be optimally matched to customer requirements.
Guide Switch Gear Siemens Lv
The prevention of personal injury and damage to equipment must however, be the first priority in any case. When selecting appropriate switchgear, it must be ensured that it is a design verified switchgear assembly ( in compliance with AC 61439-2, VDE 0660-600-2), with extended testing of behavior in the event of an internal arc fault ( IEC 61641, VDE 0660-500, Addendum 2). Low voltage main distribution systems should be chosen among those featuring a total supply power up to 3 MVA. Up to this rating, the equipment and distribution systems are relatively inexpensive due to the maximum short-circuit currents to be encountered. For rated currents up to 32006, power distribution via busbars is usually sufficient if the arrangement of the incomingloutgoing feeder panels and coupler panels has been selected in a perfor-mance-related way.
Ambient air temperatures, load on individual feeders and the maximum power loss per panel have a decisive impact on the devices to be integrated and the number of panels required, as well as their component density (number of devices per panel). Low voltage switchgear example (SIVACON S8, busbar position at rear HxWxD: 2200x4800x600 mm). Active protection measures such as the high-quality insulation of live parts (e.g. Busbars), standardized and simple operation, prevent arcing faults and the associated personal injuries. Passive protections increase personal and system safety many times over. These include: hinge and locking systems with arc resistance, the safe operation of withdrawable units or circuit breakers behind a closed door and patented swing check valves behind venitlation openings on the front, arcing fault barriers or arcing fault detection system combined with the rapid disconnection of arcing faults.
It depends among other things on the ambient temperature of the switchgear assembly, the heat flow via enclosures, if any, and/or air conditioning, the method of installation of devices (mutual heating, heat abduction, formation of hotspots), wiring (heat-flow via conductors) and last but not least the dissipated heat (load losses) of the devices. Temperature rise limit values The relevant standards such as IEC 60947-1 (low voltage switchgear) and IEC 60439-1 (Low voltage switchgear assemblies) define upper limits for the temperatures of the relevant constructive parts. IEC 60204 (Safety of machinery – Electrical equipment of machines) refers to IEC 60439-1. The high temperature of the connection point itself is permissible as after only a short distance, the conductor temperature starts to decrease due to the heat flow from the terminal point via the connected line. The conductor material (cable, busbar etc.) acts as a thermal aerial assisting in the heat dissipation process. Experience gained over many decades and with billions of terminal points confirms the correct choice of the limit values.
Typical decrease in conductor temperature with increasing distance from the terminal Decisive for the functional reliability of devices, their life span or the risk of accidents, is not the temperature-rise but the absolute temperature. The standards define temperature-rise limits for practical reasons so that tests can be performed in a laboratory environment. The reference ambient temperature in accordance with standards is 35 °C as an average over 24 hours with a maximum value of 40 °C. If the ambient temperature around the devices exceeds these values in actual service – for example because they are installed in a switching cabinet – then their load must be reduced correspondingly so that the permissible absolute temperature values are observed.
Ge Switchgear
The normal temperature range for devices in accordance with IEC 60947 is identical with the normal temperature range for switchgear assemblies in accordance with IEC 60439, in which the devices are installed. This especially affects the temperatures of internal parts of devices in respect of the thermal stability of the materials used. For reduction factors, see manufacturers documentation.