Create a template configured to trace a subnetwork, remove containers, and loop on a set of reduction rules. The rules will reduce all system and miscellaneous junctions that are connected to 0, 1, or 2 other junctions, reduce all distribution devices except circuit breakers and switches that are connected to 0, 1, or 2 other junctions, and reduce all system and miscellaneous junctions that are connected to 3 or more other junctions.
import arcpy
input_Network = "D:/MyProjectLocation/MyDatabaseConnection.sde/MyDatabase.MAP.Electric/MyDatabase.MAP.Electric"
input_DiagramTemplate = "Template1"
input_StructureJunction = "D:/MyProjectLocation/MyDatabaseConnection.sde/MyDatabase.MAP.Electric/MyDatabase.MAP.StructureJunction"
input_DistributionAssembly = "D:/MyProjectLocation/MyDatabaseConnection.sde/MyDatabase.MAP.Electric/MyDatabase.MAP.ElectricDistributionAssembly"
input_DistributionDevice = "D:/MyProjectLocation/MyDatabaseConnection.sde/MyDatabase.MAP.Electric/MyDatabase.MAP.ElectricDistributionDevice"
input_MiscJunction = "D:/MyProjectLocation/MyDatabaseConnection.sde/MyDatabase.MAP.Electric/MyDatabase.MAP.ElectricDistributionJunction"
input_SystemJunctions = "D:/MyProjectLocation/MyDatabaseConnection.sde/MyDatabase.MAP.Electric/MyDatabase.MAP.UN_112_SystemJunctions"
arcpy.nd.AddDiagramTemplate(input_Network, input_DiagramTemplate)
arcpy.nd.AddTraceRule(input_Network, input_DiagramTemplate, "ACTIVE",
"SUBNETWORK", "ElectricDistribution", "Medium Voltage",
"Low Voltage Mesh")
arcpy.nd.AddRemoveFeatureRule(input_Network, input_DiagramTemplate,
'ACTIVE', 'INCLUDE_SOURCE_CLASSES',
input_StructureJunction + ";" + input_DistributionAssembly)
arcpy.nd.AddStartIterationRule(input_Network, input_DiagramTemplate,
'ACTIVE')
arcpy.nd.AddReduceJunctionRule(input_Network, input_DiagramTemplate,
'ACTIVE', 'INCLUDE_SOURCE_CLASSES',
input_SystemJunctions + ";" + input_MiscJunction,
"MAX_2_CONNECTED_JUNCTIONS",
"REDUCE_UNCONNECTED_JCT",
"REDUCE_JCT_TO_1JCT", "REDUCE_JCT_TO_2JCTS")
arcpy.nd.AddReduceJunctionByAttributesRule(input_Network,
input_DiagramTemplate, 'ACTIVE', "",
input_DistributionDevice,
"ASSETGROUP NOT IN (4, 15)",
"MAX_2_CONNECTED_JUNCTIONS",
"REDUCE_UNCONNECTED_JCT",
"REDUCE_JCT_TO_1JCT",
"REDUCE_JCT_TO_2JCTS")
arcpy.nd.AddReduceJunctionRule(input_Network, input_DiagramTemplate,
'ACTIVE', 'INCLUDE_SOURCE_CLASSES',
input_SystemJunctions + ";" + input_MiscJunction,
"MIN_3_CONNECTED_JUNCTIONS")
arcpy.nd.AddStopIterationRule(input_Network, input_DiagramTemplate,
'ACTIVE')