حفظ کوتاه مدت میدان مغناطیسی پس از shutdown واحد، بمنظور ایجاد گشتاور ترمزی توسط تلفات القایی روی سیم پیچی ژنراتور و ترانسفورماتور متصل به آن انجام می شود.
A similar scenario could occur during shutdown. Units are often allowed to coast down under manual regulator control after being taken offline. The manual regulator is set to maintain field current at a value that would produce rated voltage at no load and rated frequency (V/Hz = 1.0).
This mode of operation uses generator and transformer losses to aid in braking during the coast down period. If the automatic regulator is mistakenly placed in service during this coast down period, overexcitation will again occur as the regulator increases excitation to maintain the voltage setpoint.