IEEE C37.121-1989 pdf free.American National Standardfor Switchgear—Unit Substations—Requirements.
IEEE C37.121 standards are listed for information only, and are not essential for the completion of the requirements ofthis standard.
ANSIIEEE C37.122-1989,Gas-Insulated Substations,Standards,Recommended Practices and Guides
ANSIC57.12.22-1989, Requirements for Pad-Mounted,Compartmental-Type, Self-Cooled, Three-Phase DistributionTransformers with High-Voltage,34 500 GrdY/19 920 Volts and below; 2500 kVA and Smaller
ANSI C57.12.24-1989,Requirements for Underground-Type Three-Phase Distribution Transformers, 2500 kVA andSmaller;High-Voltage 24,940GrdY/14,400 Volts and below; Low-Voltage 480 Volts and below
ANSIC57.12.26-1987,Requirements for Pad-Mounted,Compartmental-Type, Self-Cooled, Three-Phase DistributionTransformers with High-Voltage Bushings; High-Voltage, 34 500 GrdY/19 920 Volts and below; 2500 kVA andSmaller
ANSI C57.12.27-1982，Conformance Requirements for Liquid-Filled Distribution Transformers Used in Pad-Mounted Installations, Including Unit Substations
ANSI C57.12.40-1982,Requirements for Secondary Network Transformers，Subway and Vault Types (LiquidImmersed)
ANSIC57.12.57-1989,Transformers —Ventilated Dry-Type Network Transformers 2500 kVA and Below,Three-Phase, with High-Voltage 34 500 Volts and below, Low-Voltage 216Y/125 and 480Y/277 Volts —Requirements.
The definitions of terms contained in this standard or in other standards referenced in this standard are not intended toembrace all legitimate meanings of the terms, but are applicable only to the subject treated in this standard.Fordefinitions not given in this section, refer to ANSIIEEE C37.100-1981 and C37.100b-1985,ANSIIEEE C57.12.80-1978, and ANSL/IEEE 100-1988.
Substation: An assemblage of equipment for purposes other than generation or utilization, through which electrenergy in bulk is passed for the purpose of switching or modifying its characteristics (definition excerpted from ANSIEEE100-1988).
Unit Substation: A substation consisting primarily of one or more transformers that are mechanically andelectrically connected to, and coordinated in design with, incoming and outgoing equipment.
NOTE — For this standard, the term “unit substation” shall be limited to mean“articulated unit substation”only.
Transformer Section:A three-phase power transformer used for stepdown operation, that includes necessarymechanical and electrical connecting parts for coordination in a unit substation. Types of transformer sections aredescribed in Section 5.
Incoming Section: Equipment that includes necessary mechanical and electrical connecting parts for coordinatioin a unit substation on the high-voltage (or primary) side of a transformer section. Types of incoming sections aredescribed in Section 6.
Outgoing Section: Equipment that includes necessary mechanical and electrical connecting parts for coordinationinto a unit substation on the low-voltage (or secondary) side of a transformer section.Types of outgoing sections aredescribed in Section 7.
Transition (Throat) Section: A mechanical, electrical, and coordinated connection between a transformer sectioand an incoming section, or betweena transformer section and an outgoing section, or between different types ofincoming sections, or between different types of outgoing sections. A transition (throat) section may be (1) integralparts of two adjacent sections, or (2) an integral part of one section, or (3) a separate section.
Primary Unit Substation: A unit substation in which the low-voltage section is rated above 1000 volts.3.8 Secondary Unit Substation: A unit substation in which the low-voltage section is rated 1000 volts and below.3.9Articulated Unit Substation: A unit substation that is designed, coordinated, and assembled as multiple self-enclosed pieces of equipment intended for connection in the field.IEEE C37.121 pdf download.