diff --git a/BDNS_Abbreviations_Register.csv b/BDNS_Abbreviations_Register.csv
index 9e6f047..6f87d64 100644
--- a/BDNS_Abbreviations_Register.csv
+++ b/BDNS_Abbreviations_Register.csv
@@ -230,6 +230,7 @@ electric distribution - rectifier,REC,,IfcTransformerType,RECTIFIER,0
 electric distribution - rising busbar,RBB,,IfcCableSegment,BUSBARSEGMENT,0
 electric distribution - static transfer switch,STS,,IfcSwitchingDevice,NOTDEFINED,1
 electric distribution - switchgear (12kv typ),SWGR,,IfcElectricDistributionBoard,SWITCHBOARD,1
+electric distribution - unit substation,USS,ELECTRICAL/PANEL, IfcUnitaryEquipment,USERDEFINED,1
 electric distribution - ups panel / board,UPSB,ELECTRICAL/PANEL,IfcElectricDistributionBoard,DISTRIBUTIONBOARD,1
 electric protective device - circuit breaker,CB,,IfcProtectiveDevice,CIRCUITBREAKER,1
 electric protective device - disconnect fuse,DSCTF,,IfcProtectiveDevice,FUSEDISCONNECTOR,0