Npower provides a full range of medium voltage solutions for the utility, industrial and commercial customers with safe, reliable and smart technologies for the distribution of electricity.
The extensive global offering includes distribution automation products, switching, limiting, measuring and sensing devices, switchgear, modular substation packages and related services.
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Medium Voltage Panels Types
Each switchgear unit consists of three power compartments: circuit-breaker, busbars and cables; please refer to figure on next page. Each unit is fitted with a low voltage compartment, where all the auxiliary instruments are housed. Arc-proof switchgear is normally provided with a duct for evacuation of the gases produced by an arc; different types of gas ducts are available. All the compartments are accessible from the front and maintenance operations can correctly carried out with the switchgear installed up against a wall. The compartments are segregated from each other by metallic partitions.
The cable compartment contains the branch system for connection of the power cables to the lower contacts of the circuit-breaker. The feeder connections are made of electrolytic. Copper and they are flat busbars for the whole range of currents. For 17.5 and 24 kV they are covered with insulating material.
The earthing busbar is made of electrolytic copper and it runs longitudinally throughout the switchgear, thereby guaranteeing maximum personnel and installation safety.
Single and three-core cables up to a maximum of twelve per phase can be used depending on the rated voltage, the unit dimensions and the cable crosses section.
The switchgear can be back to wall installed, as the cables are easily accessible from the front.
The busbar compartment contains the main busbar system connected to the upper isolating contacts of the circuit-breaker by means of branch connections. The main busbars are made of electrolytic copper. For ratings up to 2 500 A, the busbars are flat bars; while for currents between 3 150 A and 4 000 A, a special D-shape busbar is used.
The busbars are covered with insulating material. There is a single busbar compartment along the whole length of the switchgear up to 31.5 kA, which optionally can be divided into compartments. For 40/50 kA these bushings are a standard feature.
Cable compartment can be fitted with an earthing switch for cable earthing. The same device can also be used to earth the busbar system (measurements and bus-tie units). It can also be installed directly on the main busbar system in a dedicated compartment (busbar applications). The earthing switch has short-circuit making capacity. Control of the earthing switch is from the front of the switchgear with manual operation, and optionally, can also be motor operated. The position of the earthing switch can be seen from the front of the switchgear by means of a mechanical coupled indicator.
Insulating Bushings and Shutters
The insulating bushings in the circuit-breaker compartment contain the contacts for connection of the circuit-breaker with the busbar compartment and cable compartment respectively.
The insulating bushings are of single-pole type and are made of epoxy resin. The shutters are metallic and are activated automatically during movement of the circuit-breaker from the racked-out position to the operation position and vice versa.