VFD With Evaporative Liquid Cooling for Extreme Conditions in Oil and Gas Installations

Large electric motors and variable frequency drives (VFDs), also known as adjustable speed drives (ASDs), rated 5 MW and above, are now widely used in the Oil and Gas industry for their reliability, efficiency, and operational flexibility. A proper selection of the electric motor and VFD technologies is paramount to meet the desired performance, optimize capital expenditure and guarantee reliability with the lowest possible operational cost. The offshore and onshore oil and gas industry is always targeting more efficient systems to optimize production platforms, refineries, and processes related to this industry. Use of high-power VFDs becomes attractive in this scenario, as losses decrease and the impact of transient conditions is minimized during startup of large motors or short circuit condition and speed control. VFD technologies typically require controlled ambient conditions, affecting the electric room HVAC (Heating, Ventilation, and Air Conditioning) system. Therefore, these applications focus on electric equipment as small and efficient as possible to minimize the impact on the layout and utility systems. These opposing necessities directly relate to the efficiency of the VFD cooling system. This paper will propose possible solution based on the evaporative liquid heatsink, where the results obtained from a 5.6 MW VFD case study demonstrates better thermal performance and an optimized design for oil and gas requirements.