Automatic Voltage Regulator (AVR)

The AVR regulates the 110V supply used by the ancillary equipment on the locomotive, such as air, compressors, vacuum exhausters, traction control management and safety systems, it also charges the locomotive’s batteries. If the voltage is too low or too high, this equipment might fail to operate correctly or over time be damaged. Battery life can be affected by incorrect charging voltage. The voltage output of a dc generator with a constant field excitation will increase or decrease in relation to the speed with which it is rotated (in our case by the diesel set). The AVR constantly monitors and regulates the excitation to the auxiliary generator to ensure the output voltage remains at 110V. The original carbon pile AVRs from Newtons, were slow to respond to changes in generator speed, resulting in the connected equipment experiencing non-ideal voltages on a regular basis. The new electronic AVR designed by an ex-BR engineer, is now fitted to all our locomotives. This responds much more quickly to changing generator output, regulating almost instantly, to keep the auxiliary voltage steady at 110V at all times