GE’s project is a result of the Dash-9 to C4 conversion that BNSF and GE first tested in 2014. To provide a converted locomotive to BNSF for evaluation, GE modified C44-9W No. 616 from a six-motor DC traction locomotive to a four-motor A1A trucked AC traction engine last year.
Internally, the converted locomotives have essentially the same traction and control systems as new ES44C4/ET44C4s BNSF has been receiving new from GE since 2009. The locomotives are being converted in GE’s San Luis Potosi, Mexico, facility and use the AC44C4M model when complete.
EMD’s program is designed to convert older SD70MACs in BNSF’s fleet to modern AC equipment found on BNSFs newer SD70ACes. BNSF’s SD70MAC fleet is currently equipped with Siemens inverter equipment which uses older gate turn-off thyristor technology as part of a more complex system. EMD’s program replaces the Siemens equipment with a Mitsubishi inverter system which features newer integrated gate bipolar transistors technology.
Each inverter on a rebuilt SD70MAC consists of three phase modules that control the power supplied to the traction motors by using integrated gate bipolar transistors to create the desired electrical voltage and frequency needed by the traction motors to achieve a specific locomotive speed. The SD70MACs are being rebuilt at Progress Rail’s Tacoma, Wash., facility.
The first locomotive to be released from San Luis Potosi was AC44C4M No. 616, arriving in the United States late last month. The locomotive was moved to Southwest Research in San Antonio for emissions testing prior to being released for service. BNSF No. 9717 departed Tacoma in late August headed to the Transportation Technology Center near Pueblo, Colo., for emissions testing as well. All 32 locomotives from both programs are expected to be delivered to BNSF by the end of the year.
Glad to see tear drop window EMDs stickin around longer, my favorite EMDs after F40Cs and F40ph of course! Yes, F40ph doesn't have tear drop windows but its my no. 1
Tier 4 standards is breathing new life into older locomotives!