IEEE Std C37.121-2020 pdf download

IEEE Std C37.121-2020 pdf download.IEEE Guide for Switch gear-Unit Substation- Requirements.
9.6 Grounding
The ground bus for each section of the unit substation should have a provision for connection to a station
ground by suitable conductors.
9.7 Nameplates
Each incoming. outgoing, and transformer section shall have a rating nameplate in accordance with its applicable standard. The nameplate should be mounted w here it is visible after normal installation.
9.8 Drawings, diagrams, instructions
The draw ings, diagrams. and instructions suppied with each unit substation should include. as applicable.
all or a combination of the following drawings or instruetions. depending on the type and complexity of the equipment:5
a) General arrangement (outline) and foundation plan
b) One-line and or three-ine diagram
c) Schemaic clementary diagram
)Conncction/ wiring diagram
e) Interconnection diagram
0 Terminal diagram
g) Control-metering-relay pancl arrangement and bills of material
1 Instruction books containing information about reeiving, handling. storage. installation, operating.
and maintenance cowering all sections and all devices mounted on or w ithin the substation
9.9 Coordination
9.9.1 Mechanical coordination and connection
If the transition (throat) section is connected to a metal-enclosed bus, it should be the responsibility of the manufacturer of the metal-enclosed bus to match the termination facilitis prov ided by the manufacturers of the transformer and incoming or outgoing section, unless otherw ise mually predetermined by the fleeted manufacturers, with the approval of the purchaser.
If the transition (throat) section consists of a close-coupled throat arrangement. it should be the responsibility
of the transformer manufacturer to match the termination facilities provided by the manufacturers of the incoming and outgoing sections unless otherw ise mutually predetermined by the afcted manufacturers, with the approval of the purchaser.
If the transition (throat) section is a compartment between equipment, such as low-voltage metal-enclosed
switchgear. metal-clad sw itchgear. or metal-nelosed-interrupter sw itchgear. the responsibility for matching
should be mually predetermined by the afected manufacturers of this equipment. with the approval of the purchaser.
Flexible conneetions should be provided for the connection between the incoming. outgoing. or transition
(throat) sctions and the bushings of the transformer cxcept for exposed cover mounted transformer bushings.
9.9.2 Secondary and control wire interconnections between sections
For adjacent and close-coupled sections. w iring and ncessary details should be provided, and wire should be isolated from power circuits rated over 600 V ac, nominal. Isolation should be by grounded metal enclosures,
metal barriers, metal conduit, electrical mallie tubing. or other approved means, except for short lengths of wire at, for example, instrument transformer terminals, temperature-measuring terminals, secondary devices, and fan-control equipment.
For remote sections, each section should be provided with terminal blocks and termial-block details for user’s extermal interconmections.
10. Typical arrangements
10.1 General
Because of the varied ratings and types of equipment, there are many possible arrangements for unit
substations. These arangements are listed in 10.2 and 10 3 and ilustrated in Figure 11 throughFiguro 23.
10.2 Primary unit substations
A primary unit substation is usually one of the following types.
a) Radial type (see igur11)
b) Distributed network type (see Figure 12)
c) Spot network type (see Figoe 13)
d) Secondary sletive lype (sce Figne 14)
e) Duplex type (see Figu 15)
Two-transformer unit substation – (aternate arangements)(see Figure 16).