Rigging
Inrush — Chain Motors
01 — Definition
Electric chain hoists swallow a very high inrush current at start-up — typically 6 to 10× full-load current for a fraction of a second. A 0.5T single-speed hoist drawing 4 A at full load can climb past 30 A on launch, and running several motors at once multiplies the inrush. Before any lift, the total inrush is always checked against the rating of the distribution circuit.
02 — In the field
A motor distribution system that trips its MCB at start-up? It is almost always inrush. Stagger the start commands where you can, and fit motor circuits with Type D MCBs — instantaneous trip at 10 to 20× rated current — so they absorb the inrush without tripping while still protecting against fault current.