IEEE C37.121-2020

$36.83

IEEE Guide for Switchgear–Unit Substation–Requirements

Published By	Publication Date	Number of Pages
IEEE	2020

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Description

Revision Standard – Active. 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.

PDF Catalog

PDF Pages	PDF Title
1	IEEE Std C37.121™-2020 Front cover
2	Title page
4	Important Notices and Disclaimers Concerning IEEE Standards Documents
8	Participants
9	Introduction
10	Contents
12	1. Overview 1.1 Scope 1.2 Purpose
13	1.3 Word usage 2. Normative references
14	3. Definitions
15	4. Service conditions 4.1 General 4.2 Usual service conditions
16	4.3 Unusual service conditions 5. Transformer section 5.1 General
18	5.2 Primary unit substation transformers 5.3 Secondary unit substation transformers
19	6. Incoming section 6.1 General 6.2 High-voltage (or primary) bushings on the transformer cover 6.3 Primary terminal chamber on the transformer 6.4 Metal-enclosed bus 6.5 Metal-clad or metal-enclosed switchgear
21	6.6 Metal-enclosed interrupter switchgear
22	6.7 Cutout, fuse, or fuse link 6.8 Metal-enclosed switchgear incorporating gas insulation systems 7. Outgoing section 7.1 General 7.2 Metal-clad switchgear
23	7.3 Metal-enclosed interrupter switchgear 7.4 Metal-enclosed bus 7.5 Metal-enclosed, low-voltage, power circuit breaker switchgear 7.6 Switchboards 7.7 Motor control centers 8. Ratings 8.1 General 8.2 Rated power frequency 8.3 Rated kVA
24	8.4 Rated high voltage (or primary voltage) and rated low voltage (or secondary voltage) 8.5 Rated continuous current 8.6 Rated short-time withstand current 8.7 Rated momentary withstand current 8.8 Rated power frequency withstand voltages
25	8.9 Rated lightning impulse withstand voltage (BIL) 9. Construction 9.1 General 9.2 Phase and polarity arrangements 9.3 Phase sequence 9.4 Metal barriers 9.5 Interlocks
26	9.6 Grounding 9.7 Nameplates 9.8 Drawings, diagrams, instructions 9.9 Coordination
27	10. Typical arrangements 10.1 General 10.2 Primary unit substations
29	10.3 Secondary unit substations
32	11. Guide for selection, application, installation, and maintenance of unit substations 11.1 Application considerations 11.2 Unusual service conditions
33	11.3 System conditions 11.4 Transformer selection
34	11.5 Load requirements 11.6 Miscellaneous design considerations
36	11.7 Installation, field-testing, operation, and maintenance
38	Annex A (informative) Bibliography
40	Back cover