Transformer Winding Connection Attributes

The ArcFM UN models every conductive object and every connection between conductive objects that exists in an electric distribution system. This includes three-phase and two-phase transformer banks connected to the conductors of their primary and secondary circuits.

For integrated applications, like ADMS, that require detailed information about transformer winding connections, the ArcFM UN uses attributes to capture the details because the information can increase the management and size of complex data. GIS users can find it much easier and faster to use attribute domains, or pick-lists, to enter accurate information about winding connections rather than use complex editing tools to visualize and edit the large set of point-to-point connections that may be involved. This action lowers the total cost of ownership when managing GIS data, without eliminating any information needed for detailed modeling and analysis. This approach supports data requirements of applications like ADMS that simulate the electrical behavior of transformers in some detail.

Recommended Configuration

The ArcFM UN configuration of a transformer bank offers one, two, or three phase-specific paths, with unit objects, between one pair of terminals on the bank, that supports a model of phase propagation through the transformer.
Four descriptive fields, taken together, can specify connectivity in a way that supports the construction of a detailed topological model of each point-to-point connection among all available physical terminals on the transformer equipment (including center taps) and the available primary, secondary and neutral conductors, by applications that require that level of detail in the GIS data.
- The PrimaryConnectionType and SecondaryConnectionType attributes of the transformer bank feature (in the Device feature class) are used to specify the overall wiring strategy for the bank. Each contains an integer code value that indicates a choice from a list, such as Wye, Delta, Grounded-Wye and Open Delta. Additional codes can be used to capture additional connection strategies.
- The PrimaryWindingConnection and SecondaryWindingConnection attributes on each of the transformer unit records allow each unit to indicate the specific role that it plays in the overall wiring strategy for the bank. The suggested coded-value domain for each of these fields consists of two values. A value of LL to indicates that the winding is connected line-to-line (phase-to-phase), and a value LG to indicate a winding that is connected line-to-ground (phase-to neutral or phase-to-ground), in relation to the circuit to which the winding is connected (primary or secondary). Some configurations may choose to include named-phase entries in the domain, AB, AC, BC (specific line-to-line connections), AN, BN, CN (specific line-to-ground connections).

Transformer Network Categories

Network Category Name	Applicable tables	Description
E:Transformer	Device JunctionObject	Applies to all device asset groups and asset types that represent a transformer bank or all JunctionObject asset groups and asset types that represent a contained phase-associated unit (which may be a single-phase unit or a three-phase unit) of a transformer bank.
E:Transformer - Tap	Device JunctionObject	Applies to all types within the transformer category that follow the tap connection style for transformers in the ArcFM UN electric model. This category may be used by editing tools.
E:Transformer - Inline	Device JunctionObject	Applies to all types within the transformer category that follow the in-line connection style for transformers in the ArcFM UN electric model. This category may be used by editing tools.
E: Transformer - Three Winding	Device JunctionObject	Applies to all types within the transformer category that possess a tertiary winding. This category may be used by editing tools.
E:Transformer - Open Delta	Device JunctionObject	Applies to all device asset groups and asset types that represent an open delta transformer bank. This category may be useful for specifying conditions used by trace configurations and propagators in the UN, and it may also be used by applications that need to identify transformer banks that use the open delta connection pattern.
E:Transformer – Open Wye	Device JunctionObject	Applies to all device asset groups and asset types that represent an open delta transformer bank. This category may be useful for specifying conditions used by trace configurations and propagators in the UN, and it may also be used by applications that need to identify transformer banks that use the open wye connection pattern.
E:Has Connected Units (Unbalanced)	Device	The purpose of this category is to identify a type of device or conductor that requires units, in the bank/unit containment pattern, to carry phase-specific attributes and/or indicate continuity of a named phase through the device or conductor.
E:Has Disconnected Units (Balanced)	Device	Phase-Specific attributes carried at the device level only.
E:Overhead	Device JunctionObject	Used to denote which transformers are installed on overhead poles
E:Underground	Device JunctionObject	Used to denote which transformers are installed for underground equipment
E:Submersible	Device JunctionObject	Used to denote which are designed for underwater connections
E:Unit	JunctionObject	Applies to all JunctionObjects that are contained within a bank that has the E:Has Connected Units or E:Has Disconnected Units category

Transformer Bank Attributes (Unbalanced)

These attributes are implied by the Transformer network category, and so they may be found on both the device feature class and the JunctionObject table, since a transformer bank can be a spatial or a non-spatial entity in the ArcFM UN model.

Name	Data Type	Description	Sample Data
PhasesNormal	Short or Long Integer	Domain coded value. Value should reflect the combination of the phases that are covered by the contained transformer units.
RatedKVA	Floating Point	Total kVA rating for the bank (adding up kVA ratings of the units)	25 50 300
VoltageGroup	Short or Long Integer	Domain coded value. Indicates the operating voltage at the primary terminal of the transformer, and should match the VoltageGroup code of each external feature, not counting the units, that is connected to the primary terminal.
PrimaryConnectionType	Short or Long Integer	Domain coded value. Indicates a connection strategy for the primary winding of each transformer unit in the bank.	1 = “Y” 2 = “Delta” 3= “Open Delta” 4= “Open Y”
SecondaryConnectionType	Short or Long Integer	Domain coded value. Indicates a connection strategy for the secondary winding of each transformer unit in the bank.	1 = “Y” 2 = “Delta” 3=”Open Delta” 4= “Open Y”
TertiaryConnectionType	Short or Long Integer	Domain coded value. Indicates a connection strategy for the tertiary winding of each transformer unit in the bank.	1 = “Y” 2 = “Delta” 3= “Open Delta” 4= “Open Y”

Transformer Bank Attributes (Balanced)

Name	Data Type	Description	Sample Data
VoltageGroup	Short or Long Integer	Describes the voltage(s) going into the transformer’s primary winding.
LowSideVoltageGroup	Short or Long Integer	Describes the voltage available at the transformer’s secondary winding.

Transformer Unit Attributes

These attributes are implied by the combined assignment of the E:Transformer and E:Unit network categories, and found on the ElectricJunctionObject table. These attributes are found on the ElectricJunctionObject table and are used by the rows in that table that represent units belonging to a transformer bank.

Transformer Unit Attributes

These attributes are implied by the combined assignment of the E:Transformer and E:Unit network categories. They are found in the ElectricJunctionObject table and are used by the rows in that table that represent units belonging to a transformer bank.

Name	Data Type	Description	Sample Data
PhasesNormal	Short or Long Integer	Domain coded value. Value should be a single phase, except when the unit represents a symmetrical 3-phase transformer
RatedKVA	Floating Point	kVA rating of the transformer unit (total kVA rating for the bank if this is a symmetrical 3-phase unit)
VoltageGroup	Short or Long Integer	Domain coded value. Describes the voltage(s) going into the transformer’s primary winding.
LowSideVoltageGroup	Short or Long Integer	Domain coded value. Should match the VoltageGroup of each feature connected to the Secondary terminal of the parent transformer. This is the one that propagates, if using a voltage propagator.
PrimaryWindingConnection	Short or Long Integer	Domain coded value.	1 = “LG” 2 = “LL”
SecondaryWindingConnection	Short or Long Integer	Domain coded value.	1 = “LG” 2 = “LL”