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26 10 00 MEDIUM-VOLTAGE ELECTRICAL DISTRIBUTION

 

DocumentVersion DateDescription
Medium Voltage DistributionMarch 2022Medium Voltage Distribution

26 10 00 MEDIUM VOLTAGE DISTRIBUTION

.01 General
  1. The design professional shall be responsible for medium voltage equipment and infrastructure layouts and coordination plans for the transformer and/or any other ancillary medium voltage devices. PSU Engineering Services Electrical Group shall be apprised during the schematic design phase and no later than DD phase. This applies to all PSU campus locations.
  2. System Voltage
    1. At University Park, service shall be provided from the 12,470VAC distribution network. The 4,160VAC network is NOT to be used unless expressly approved by PSU Engineering Service Electrical Group, Utility Engineers.
    2. At other locations (Commonwealth Campuses or outside of University Park’s utility infrastructure), services may be provided by a local utility or the campus distribution network as appropriate. Details will be provided by PSU Engineering Services Electrical Group Utility Engineers as required.
    3. Note, other campus locations where PSU owns some level of MV distribution include Abington, Altoona, Brandywine, Erie, Greater Allegheny, Harrisburg, Mont Alto, Wilkes-Barre, and York
  3. Contacting the Electrical Utility Provider
    1. At University Park, the design professional shall contact PSU Engineering Services Electrical Group, Utility Engineers for any details pertaining to the University Electrical Utility system.
      1. Per Section 26 00 00 .01 9., any projects involving new buildings, major renovations, new electrical services or electrical service upgrades require the completion and submission of the Electrical Load Determination, or PSU Elec Load Information, document. This document should also be submitted for any electrical service removals.
    2. At Commonwealth locations, the design professional shall contact PSU Engineering Services Electrical Group Utility Engineers, prior to reaching out to any electrical utility provider.  Once initial contact is made with PSU, and after discussions with the local utility provider, the design team may contact the local utility directly, provided PSU Utility Engineer(s) are copied on all correspondence.
  4. University Park – District Emergency and Standby System
    1. Emergency and Standby power (backup power) is distributed throughout the campus and is available at certain buildings and locations on campus.  This distributive system is utilized as a backup power system, in lieu of individual local on-site generation.  Local on-site generation is NOT recommended, if the backup power system is readily available nearby.
    2. The backup power system is a network of 5000VAC, three phase circuits throughout the University Park campus.
    3. At University Park the design professional shall consider this system and determine if the utility is readily available in the project area. Confer with PSU Engineering Services Electrical Group, Utility Engineers on the requested amount of backup powered required and if the system can handle the expansion.
    4. The backup utility is a finite resource and great care must be taken to avoid unintended or erroneous loads being placed on the system. The design professional shall perform and submit load calculations regarding the emergency and Standby systems, to PSU Engineering Services Electrical Group, Utility Engineers for consideration.
  5. Medium Voltage System Design
    1. The Design Professional is responsible for providing PSU a complete medium voltage design, while conforming to PSU Design and Construction Standards outlined within Division 26.  The Design Professional shall keep PSU Engineering Services Electrical Group Utility Engineers continuously apprised throughout the design and construction phases until project completion.
    2. The Design professional shall utilize 15,000VAC rated equipment for all substations, selector switches and conductors regardless of actual system voltage, i.e., 15,000VAC rated conductors utilized on a 5,000VAC system.
    3. The Design Professional is responsible for performing and submitting load calculations for the building service, which shall be submitted to PSU Engineering Services Electrical Group, Utility Engineers for consideration in sizing the transformer.
    4. The Design Professional shall forward all medium voltage submittals to PSU for Approval. PSU shall be afforded two weeks minimum for all medium voltage submittal reviews.
    5. Cable sizing shall be done by PSU Engineering Services, Electrical Group – Utility Engineers. The Design professional shall utilize only the common cable sizing as listed

        1. 2 AWG
        2. 2/0 AWG
        3. 350 KCMIL
        4. 500 KCMIL

  6.                                                              ii.      Note, these common sizes are normally stocked or installed on the premises. Other cable sizes will not be permitted without the express and written approval of the PSU Engineering Services Electrical Group Utility Engineer.

                                                               iii.      Design Professional shall utilize Division 26 05 13 – Medium Voltage Cables and Terminations Guide Specification.

    1. PSU will be responsible for sizing and procurement of building transformers at University Park and certain commonwealth locations. The Design professional shall coordinate with PSU Architects and Engineering Services Electrical Group, Utility Engineers to come to an agreement on site location. However, transformer location shall not be more than 150 feet away from the building with a voltage drop of no more than 2%. Design Professional shall reference Division 26 05 43 for transformer vault details.  Transformers shall be installed on vaults only, concrete pads are not acceptable.
    2. The Design Professional shall inform PSU Engineering Services, Electrical Group – Utility Engineers on the intended placement of the building transformer within the timeline of SD & DD phases of the project. The location of the transformer directly correlates with how the transformer will be specified and purchased.
    3. Any medium voltage switches that will be required as part of the project or that are required by PSU shall be the responsibility of the Design Professional to capture in the design phase.  Design professional shall include any additional components or controls for integration into the PSU Medium Voltage SCADA system, PSU will coordinate appropriate specifications.  For switch site location and coordination utilize and reference Division 26 05 43 for switch vault details.

                                                                   i.      Reference Division 26.13.16.13. Switches rated maximum 5.5kV, 200A shall be procured and installed by the project. These are typically indoor rated to provide emergency and/or standby service disconnect. Basis of design is Eaton Mini MVS Switch and Square D MiniBreak.

                                                                 ii.      PSU will procure pad mounted MV switches (S&C Vista, PMH) for UP (University Park) campus distribution.  Consult PSU Engineering Services Electrical Group for MV switch type and configuration, however basis of design shall be either S&C Vista or PMH models.

                                                               iii.      All MV switches shall be installed on a vault, concrete pads are not acceptable.

    1. The Design Professional is responsible for ductbank routing from a predetermined PSU manhole and respective circuit to power the project. During Schematic Design PSU will evaluate manhole and circuitry availability, with a determination no later than the 50% Design Development. The Design Professional is responsible for the ductbank construction as referenced in Division 26 05 43.
    2. Medium voltage Emergency and Standby transformers shall be included in the design of emergency/standby electrical rooms. The design professional shall coordinate with PSU for the size of the transforms. PSU will size the emergency and transformers; design professional shall ensure proper location and physical size constraints are met. Emergency and Standby transformers that are smaller than 150kVA, are required to be indoor dry type transformers, reference Division 26 12 16; 150kVA and larger are required to be outdoor rated oil filled, of which PSU will procure these transformers.  Design consultant shall coordinate will PSU on transformer sizing and site location.
    3. Medium voltage shall be isolated from low voltage conductors and shall be installed in Rigid Metal Conduit or Electric Metallic Tubing, when exposed in the interior of buildings, facilities and/or utility plants.
    4. Identify any medium voltage (1000V and greater) raceway system(s) within a building, by painting raceway system(s) RED, in its entirety and stenciling the nominal phase-to-phase voltage in WHITE paint, at least once and no more than 20ft apart between markings.

 

26 11 00 SUBSTATIONS

26 11 16 Secondary Unit Substations

.01 General
  1. 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.
  2. Taps, two at 2-1/2% and each alone and two at 2-1/2% each below normal shall be provided.
  3. 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
  1. This work is typically installed by PSU Utility Services.  Discuss medium voltage pad-mount transformer project requirements with Engineering Services.
  2. Provide transformer foundation for exterior locations.  Ground per “Grounding” section below.
  3. 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.
  4. Where fuses are used, a complete set of spare fuses shall be provided.
  5. Provide complete information, instructions, wiring diagrams and manuals for maintenance and servicing.

.02 Grounding
  1. 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.
  2. 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.

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