Iec 60034-9 Pdf [2025]

At no load, magnetic noise (often dominant in induction motors) is present, but fan noise may be lower if the motor is self-cooled? Actually, fan noise is speed-dependent, not load-dependent. For TEFC motors, the internal fan runs at same speed regardless of load. But aerodynamic noise from rotor surface may change. Full load often adds 1–3 dB due to load-dependent magnetic forces.

Encourage manufacturers to design quieter cooling systems and magnetic circuits. Key Technical Specifications iec 60034-9 pdf