Waste heat is reduced as the efficiency is typically 91%. A low audible noise figure of 44.3dBA is achieved through the use of low speed fan cooling. This reduces operator fatigue during operation. The QM series meets EN55011 and EN55032 level B for both conducted and radiated noise, even with a low 300µA leakage current. A 5,000m altitude specification is achieved for both operational, storage and transportation conditions.