Electrical Transformation Centers: Components and Functionality

Posted on Mar 1, 2025 in Geology

Electrical Transformation Centers (CT) provide the installation of transformers, reducing high to low tension, complemented by switchgear for precise work. Their function is to distribute electrical energy at different voltages while allowing connection to the line at any point.

CT Classification:

  • Feeding: (in a point and in step)
  • Property: (company-owned, subscriber/customer-owned)
  • Location: (outdoor or indoor)
  • Construction: (aerial, underground, conventional, prefabricated compact)

CT Feeding Types:

  • Feeding in a Point: Disposes of one feeding line and referral, connected to the core network, the endpoint constitutes a DIXA network.
  • Feeding in Step: There is one input line and one output line towards another center.

CT Ownership:

  • Company CT: Properties of the supplier company.
  • Subscriber or Customer CT: Customer properties, and the feeding tension is conditioned by the network supplying the company.

CT Location:

  • Weather or Air CT: Normally constituted by one transformer not exceeding 160kVA, protected by fuses and sitting.
  • Internal CT: Located in closed areas with two variants:
    • Surface: Has a level of access to the street, possibly part of a building.
    • Underground: Not installed under the public highway.
  • CT with Aerial Assault
  • CT with Underground Assault
  • Conventional CT: Located inside enclosures constructed of bricks, stone, or concrete.
  • CT Panel: Meets the needs of small sizes, easily transportable and installed, with maximum atmospheric resistance to agents. Can be surface or underground.

Modular Cell Types:

  • CML-d cell: Line cell
  • CMP-F cell: Protecting and fuses cell
  • CMP-to cell: Automatic switch cell
  • CMIP cell: Switch passing cell
  • CMM-d cell: Media cell
  • WRC cell: Lift cell

Transformers

Two types of low voltage: B1 (231/133V), B2 (420/242V).

EBT Constitution:

  • Medium Tension Bushings: Responsible for the interconnections of the transformer windings and the arrival of the medium tension network.
  • Low Tension Bushings: Responsible for the interconnections of the transformer windings with the BT network output.
  • Cuba: The deposit contains refrigerant liquid where the nucleus and transformer windings are immersed. It closes with an upper lid perimeter screwed to Cuba, serving to support the active part of the transformer.
  • Expansion Deposit: Located in the upper part of Cuba and communicating with it, to safeguard the inundation of Cuba, while serving as an expansion chamber for oil due to temperature variations.
  • Oil Level Indicator: A window to observe the oil level, placed on both sides of the expansion tank.
  • Desiccator: Located in the communication line with the atmosphere and has the mission of ensuring that the air entering the transformer is dry, as the oil level diminishes. This can be produced either by lowering temperature or an oil leak. It is formed by a recipient containing silica gel gravel.
  • Thermostat: They can be column type (indicate only the temperature of the transformer oil) or sphere type (which, in addition to the above, have adjustable contacts for any desired value to cause fire alarms or transformer shutdown).

Internal Constitution:

  • Magnetic Core: Constitutes the road which establishes magnetic flow and is formed by sheets of ferromagnetikas steel alloy 0.35 mm thick at the base of silicium between 3 and 5% and isolated electrically from each other.
  • Windings: Constituted by copper coils of rectangular or circular aluminum section.

General Characteristics:

  • Primary Tension: The feeding tension of the transformer.
  • Maximum Service Tension: The level is greater than the tension produced by the transformer and operating in steady state (24kV-36kV).
  • Rated Secondary Network Tension: B1-230/127V; B2-400/230V.
  • Primary Rated: The intensity that the creek runs through the transformer primary when it is supplying rated power.
  • Voltage Short Circuit: The voltage that must be applied to the transformer primary circuit so that, on the short side booth, it circles on its rated current.
  • Rated Secondary: The intensity that runs the transformer secondary streams when it provides the nominal power.
  • Orario Index: Defines the angle between the primary and secondary voltages. This number corresponds to the number indicated by the small hand on a clock.
    • 0 degrees gap, orario index: 0
    • 330 degrees gap, orario index: 11
    • 180 degrees gap, orario index: 6
    • 150 degrees gap, orario Index: 5