The basis for the coordination of equipment in unit substations by assisting in the selection of components is intended as the use of this guide. A variety of designs for unit substations are possible using various combinations of incoming sections, transformer sections, outgoing sections, and transition sections. It is intended that the incoming, outgoing, transformer, and transition sections included in a unit substation meet the basic requirements of applicable industry standards for those sections. This guide covers three-phase unit substations for stepdown operation in the range of 112.5 kVA or greater at primary voltages of 601 V through 38 kV.
- Standard Committee
- PE/SWG - Switchgear
- Status
- Superseded Standard
- PAR Approval
- 2011-09-10
- Superseded by
- C37.121-2020
- Superseding
- C37.121-1989
- Board Approval
- 2012-12-05
- History
-
- ANSI Approved:
- 2014-10-28
- Published:
- 2013-02-22
Working Group Details
- Society
- IEEE Power and Energy Society
- Standard Committee
- PE/SWG - Switchgear
- Working Group
-
SA/C37.121 - C37.121 - Guide for Switchgear-Unit Substation--Requirements
- IEEE Program Manager
- Jennifer Santulli
Contact Jennifer Santulli
Other Activities From This Working Group
Current projects that have been authorized by the IEEE SA Standards Board to develop a standard.
No Active Projects
Standards approved by the IEEE SA Standards Board that are within the 10-year lifecycle.
C37.121-2020
IEEE Guide for Switchgear--Unit Substation--Requirements
The basis for the coordination of equipment in unit substations by assisting in the selection of components is intended as the use of this guide. A variety of designs for unit substations are possible using various combinations of incoming sections, transformer sections, outgoing sections, and transition sections. It is intended that the incoming, outgoing, transformer, and transition sections included in a unit substation meet the basic requirements of applicable industry standards for those sections. This guide covers three-phase unit substations for step-down operation in the range of 112.5 kVA or greater at primary voltages of 601 V through 52 kV.
These standards have been replaced with a revised version of the standard, or by a compilation of the original active standard and all its existing amendments, corrigenda, and errata.
C37.121-1989
American National Standard for Switchgear - Unit Substations - Requirements
This standard covers the requirements for three-phase unit substations for step-down operation in the range of 112.5 kVA through 10 000 kVA at primary voltages of 601 volts through 38 kilovolts. The standard is intended for use as the basis for the coordination of equipment by assisting in the selection of components. A variety of designs for unit substations are possible using various combinations of incoming sections, transformer sections, outgoing sections, and transition (throat) sections. Since the transformer section determines the kVA and voltage capabilities of a unit substation, the ratings of the various types of unit substations are described in terms of transformer capability.
These standards have been removed from active status through a ballot where the standard is made inactive as a consensus decision of a balloting group.
No Inactive-Withdrawn Standards
These standards are removed from active status through an administrative process for standards that have not undergone a revision process within 10 years.
No Inactive-Reserved Standards