Number of MV/LV transformers
From Electrical Installation Guide
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
