Asynchronous modes and self-excitation of synchronous machines

In the practice of synchronous machines, there are cases where individual machines fall out of sync and their rotors begin to rotate relative to the field of the armature (stator) asynchronous, with some sliding s. This is due to overloading of machines, a significant drop in voltage in the network and loss of excitation as a result of any faults in the excitation system or erroneous operation of the field blanking machine. Although a non-excited explicit pole machine can develop a certain power in synchronous mode due to the reactive moment, this power is usually insufficient to cover the load, and so clearly pole machines most often also fall out of sync when the excitation is lost.