This Technical Specification covers requirements for electric pumps which generate the circulation of insulation liquid in traction transformers and reactors of rail vehicles and their associated cooling system. The pumps covered by this Technical Specification are rotodynamic pumps driven by a squirrel cage induction motor which is immersed in the insulating liquid. CLC/TS 50537-2 gives consideration to both technical and normative requirements of the railway environment and restricts the variety provided by industry-wide standards for pumps (for example EN 50216-7 and EN ISO 9906). It determines requirements and tests enabling the interchangeability especially regarding electrical, mechanical and hydraulic interfaces. Furthermore, service conditions are described.