Cabinet Cooling

The drive power of the high performance AC locomotive is provided by a traction current converter, which is installed in the main converter cabinet. The locomotive is also equipped with two independent auxiliary power converter cabinets. The auxiliary power converters supply power to the ancillary units such as cooling fan, water and oil pump, air conditioning unit, main compressor as well as battery chargers, heating units and other additional equipment. The auxiliary power converters are operated redundantly: one converter in normal operation and one in standby mode. With such a large number of connected loads, the fault-free operation of the locomotive largely depends on the function of the converters and the cabinets in which they are installed.

The temperature in the control cabinet rises the longer the converters are in operation. The cabinets are therefore equipped with an active air cooling system in order to remove the resulting heat. The air circulation must be monitored constantly in order to ensure that permanent cooling continues without interruption. The specialists building the locomotive went in search of a sensor solution that provided a steady output signal when the flow was constant, irrespective of any temperature changes. It also required a solution that could be installed in the restricted space of the converter cabinet without any problems.

Turck solution: Aligned fitting

Turck's M18 flow sensors for gaseous media proved to be the sensor solution that could meet all the locomotive manufacturer's requirements. The FCS-M18-LIX is a compact flow sensor in a cylindrical housing with a male thread that enables it to be mounted even in restricted spaces. Although the calorimetric measuring principle used here is susceptible to temperature changes, the Turck sensor compensates for this with its special sensor design and a so-called aligned fitting: The measuring resistor and the heatable measuring resistor have to be positioned parallel to the flow direction. The aligned fitting enables the full precision potential of the sensors to be used. If the sensor was incorrectly fitted, the heated air could also cause the measurement to be incorrectly interpreted as a change in flow. With aligned fitting on the other hand, the sensor cannot be affected by temperature changes of the passing air current.

Once the FCS-M18-LIX, specially designed for gaseous media, is correctly aligned, it now reliably monitors the flow with the electric locomotives in continuous operation – even when the temperature increases. The Turck sensor therefore also helps to keep the maintenance times of the locomotive to a minimum and to improve its efficiency. Turck's flow sensor also fulfills the second customer requirement on account of its compact design which combines sensor, probe and processing unit in a single housing. Sensors with a larger housing style or with separate processor units could not be installed in the conditions at hand.