Indoor unit substations may be required under certain designs. Where used, these shall be three-phase units equipped with a loadbreak fused switches, with current limiting fuses. SF6 gas insulated equipment shall not be used unless approved by Engineering Services.
Taps, two at 2-1/2% and each alone and two at 2-1/2% each below normal shall be provided.
Where indoor transformer rooms are used, they must be adequately ventilated with powered ventilators, dampers, and a suitable control system.
26 12 00 MEDIUM-VOLTAGE TRANSFORMERS
.01 Distribution Transformers
This work is typically installed by PSU Utility Services. Discuss medium voltage pad-mount transformer project requirements with Engineering Services.
Provide transformer foundation for exterior locations. Ground per “Grounding” section below.
Indoor oil-filled transformer, when approved by Engineering Services, shall be FM approved (not just the oil itself). Contact Engineering Services for minimum efficiency requirements.
Where fuses are used, a complete set of spare fuses shall be provided.
Provide complete information, instructions, wiring diagrams and manuals for maintenance and servicing.
All electrical systems shall be suitably grounded, including all non-current carrying metallic components of all equipment and metallic conducts. Grounding shall be accomplished as required by the National Electric Code.
Provide minimum 2/0 AWG bare copper ground ring with at least two (2) 96” ground rods around transformer foundation. Exothermically weld rods and ring. Ring shall be a minimum of 24” from the edge of the foundation, buried between 18” and 24” deep. Rods shall be installed at opposite corners or at a distance of more than rod length apart. Extend cabling a minimum of 48” above grade for connection to transformer. Do not connect this ground ring to the building service.