Number of MV/LV transformers: Difference between revisions

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For every MV/LV substation, the definition of the number of MV/LV transformers takes into account the following criteria:
Main characteristics to consider to determine the number of transformers:  
* Total power supplied by the substation
 
* Standardization of the rated power to reduce the number of spare transformers
*Surface of building or site
* Limit of the rated power. It is recommended to set this limit at 1250 kVA in order to facilitate the handling and the replacement of the transformers
*Total power of the installed loads
* Scalability of the installation
*Sensitivity of circuits to power interruptions
* Need to separate the loads having a high level of sensitivity to the electrical perturbations
*Sensitivity of circuits to disturbances
* Need to dedicate a transformer to the load generating a high level of perturbation such as voltage dips, harmonics, flicker
*Installation scalability
* Need for partial or total redundancy. When required, two transformers each sized for the full load and equipped with an automatic change-over are installed
 
* Loads requiring a dedicated neutral system. IT for example to ensure the continuity of operation in case of phase to earth fault
The basic preferred configuration comprises a single transformer supplying the total power of the installed loads. Certain factors contribute to increasing the number of transformers (&gt; 1), preferably of equal power:
 
*A high total installed power (&gt; 1250kVA): practical limit of unit power (standardization, ease of replacement, space requirement, etc),
*A large surface area (&gt; 5000m²): the setting up of several transformers as close as possible to the distributed loads allows the length of LV trunking to be reduced
*A need for partial redundancy (down-graded operation possible in the case of a transformer failure) or total redundancy (normal operation ensured in the case a transformer failure)
*Separating of sensitive and disturbing loads (e.g.: IT, motors)<br>
 
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Latest revision as of 09:49, 22 June 2022

For every MV/LV substation, the definition of the number of MV/LV transformers takes into account the following criteria:

  • Total power supplied by the substation
  • Standardization of the rated power to reduce the number of spare transformers
  • Limit of the rated power. It is recommended to set this limit at 1250 kVA in order to facilitate the handling and the replacement of the transformers
  • Scalability of the installation
  • Need to separate the loads having a high level of sensitivity to the electrical perturbations
  • Need to dedicate a transformer to the load generating a high level of perturbation such as voltage dips, harmonics, flicker
  • Need for partial or total redundancy. When required, two transformers each sized for the full load and equipped with an automatic change-over are installed
  • Loads requiring a dedicated neutral system. IT for example to ensure the continuity of operation in case of phase to earth fault
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