Sizing this 80 A manual motor starter for the motor branch
The ABB MS165-80 is a manual motor starter rated 80 A at 400 V AC — the current rating sets the overload protection threshold for the motor branch, not the continuous carry current of the contacts. In AC-3 duty (starting and stopping squirrel-cage motors under load), the 80 A rating typically covers a motor full-load current up to roughly that value, though the actual trip setting is adjustable on the unit. This is a direct-acting thermal-magnetic device: the thermal bimetal handles overload protection (slow response to sustained overcurrent), while the magnetic trip clears short-circuit faults fast. No separate overload relay is needed in the branch — the MS165 combines disconnect, short-circuit, and overload protection in one DIN-rail footprint.
Where it lands in the panel
The MS165-80 snaps onto a standard 35 mm DIN rail inside a motor control centre or distribution panel. It serves as the primary branch protection for a single motor load — typically a pump, fan, conveyor, or compressor — and provides a local manual on/off/isolate handle at the starter itself. In a typical MCC bucket, the MS165 sits ahead of the contactor and downstream of the main bus. The 80 A rating at 400 V AC is common for moderate-sized three-phase induction motors in the 30–40 kW range, depending on the motor's full-load current and service factor.