Complex sentence: When a transformer is first energized a transient current up to 10 to 50 times larger than the rated transformer current can flow for several cycles, using less copper for the same power handling, typically toroidal transformers can have up to 60 times inrush to running current.
Split into simpler sentences: When a transformer is first energized, a transient current up to 10 to 50 times larger than the rated transformer current can flow for several cycles. Toroidal transformers, using less copper for the same power handling, can have up to 60 times inrush to running current.