During field balancing the rotor that must be balanced is mounted on its own bearings and driven at its normal operating speed. The rotor does not have to be removed from the housing. Removal can cause a considerable amount of downtime. Field balancing usually results in lower vibration levels because the balancing process is executed at the final operating speed, with the machines own bearings and drive system. Some on-site factors such as aerodynamics, misalignment and structural effects are also accommodated.
Field balancing is suitable for rotors with complete access to planes and switching motor on or off is available. The drawback is that it is less convenient for the person doing the balancing because the balancing machine must be transported to the site. Furthermore, there are risks involved, such as loose balancing weights being thrown from a high speed rotor.