diff --git a/cimsparql/data_models.py b/cimsparql/data_models.py
index 17292525..f78d75af 100644
--- a/cimsparql/data_models.py
+++ b/cimsparql/data_models.py
@@ -160,7 +160,6 @@ class PhaseTapChangerSchema(JsonSchemaOut):
 
 class ConvertersSchema(NamedResourceSchema):
     alias: Series[str] = pa.Field(nullable=True)
-    substation_mrid: Series[str] = pa.Field()
     status: Series[bool] = pa.Field()
     node: Series[str] = pa.Field()
     p: Series[float] = pa.Field()
@@ -173,7 +172,6 @@ class ConvertersSchema(NamedResourceSchema):
     loss1: Series[float] = pa.Field()
     loss2: Series[float] = pa.Field()
     vdcn: Series[float] = pa.Field()
-    un: Series[float] = pa.Field()
 
 
 ConvertersDataFrame = DataFrame[ConvertersSchema]
diff --git a/cimsparql/sparql/converters.sparql b/cimsparql/sparql/converters.sparql
index d8e67637..74f12d5c 100644
--- a/cimsparql/sparql/converters.sparql
+++ b/cimsparql/sparql/converters.sparql
@@ -3,7 +3,7 @@ PREFIX cim:<${cim}>
 PREFIX xsd:<${xsd}>
 PREFIX SN:<${SN}>
 PREFIX ALG:<${ALG}>
-select ?mrid ?name ?alias ?p ?q ?substation_mrid ?status ?node ?connectivity_node ?controller ?controller_factor ?pole_loss ?loss0 ?loss1 ?loss2 ?vdcn ?un
+select ?mrid ?name ?alias ?p ?q ?status ?node ?connectivity_node ?controller ?controller_factor ?pole_loss ?loss0 ?loss1 ?loss2 ?vdcn
 where {
   {
     select * where {
@@ -30,10 +30,7 @@ where {
                   cim:Terminal.sequenceNumber|cim:ACDCTerminal.sequenceNumber 1 .
         ?con_node cim:IdentifiedObject.mRID ?connectivity_node;
 		  cim:ConnectivityNode.ConnectivityNodeContainer ?con_node_container.
-	?con_node_container cim:VoltageLevel.Substation ?substation;
-		      cim:VoltageLevel.BaseVoltage/cim:BaseVoltage.nominalVoltage ?un.
-        ?substation cim:IdentifiedObject.mRID ?substation_mrid;
-          cim:Substation.Region/cim:SubGeographicalRegion.Region/cim:IdentifiedObject.name ?area .
+	?con_node_container cim:VoltageLevel.Substation/cim:Substation.Region/cim:SubGeographicalRegion.Region/cim:IdentifiedObject.name ?area .
         optional {?converter SN:Equipment.networkAnalysisEnable ?_analysis_enabled .}
 	optional {
           ?converter ALG:VoltageSourceConverter.loss0 ?_loss0;