For a long time, the German railways (DB) had a framework contract with Bombardier for the delivery of Traxx AC/AC1/AC2 locomotives for its passenger services. Over time, several tranches were ordered. Two tranches represent the Traxx AC2 platform:
DB Regio 146 201-247: delivered to DB Regio 07.2005 - 10.2006
DB Regio 146 251-282: delivered to DB Regio in 2015 (251 built in 2013, 252 in 2014)
The 146 201-247 were delivered initially for services around Stuttgart, Ludwigshafen, Freiburg, and Nurnberg. There were different sub batches: 201-222, 240-247 and no. 223-239 that came last. Officially, 146 229 was the 100th 146s series locomotive being delivered to the DB (after 146 001-031 and 146 101-132).
146 228 is also a curious machine, as it was taken out of the ongoing production of 185.2 series machines for DB Schenker. Being an experiment, the planned 185 400 was delivered in 2006 to DB Regio, numbered as 146 228! By doing this Bombardier could demonstrate the flexibility of the Traxx 2 platform.
Internally, DB Regio refers to 146 251-282 as sub series 146.3.