Mitsubishi HF75S Servo Motor: Complete Technical Guide for Industrial Automation

What this delivery is: a Mitsubishi HF75S-A51 AC servo motor — the 750 W low-inertia HF-S series frame, with the built-in brake that the -A51 suffix carries — brand new in its factory carton, received stock uploaded 2025-11-25. Three markings agree on the type: the carton label reads G NAME HF75S-A51, a white sticker on the rear housing prints HF75S-A51, and the nameplate's short form HF75S sits above the full rating block. The nameplate carries INPUT 3AC 181V 3.1A, OUTPUT 0.75KW per IEC60034-1:99, 4000 r/min, IP67, insulation Class F, and 2.5 kg — which settles the delivery tag's own contradiction (its weight field said 15 kg while its text said 2.5 kg; the nameplate and carton both say 2.5 kg, so 15 kg was a data-entry slip we report and correct).

Reading the motor

The HF75S is the 750 W member of Mitsubishi's HF-SN low-inertia family in the 80 mm square flange class. The built-in brake is the visible difference: the rear housing extends into a plain black cylinder — the brake assembly — ahead of the connector panel, and it holds the shaft stationary when the amplifier removes enable, which is why this variant is the one for vertical axes and Z motions. Wiring is a pair of round connectors on the housing flank: a heavy four-pin power receptacle with a threaded shell for the gland nut, and a smaller multi-pin encoder connector below it; both arrived sealed with red CAPLUGS EC-18 caps, and a yellow triangle warning sticker marks the hot-surface case. The front flange seats an O-ring in its groove with the four corner bolts, the front cover is finned, and the keywayed shaft came wrapped in kraft paper under orange tape. The carton label completes the record: M CODE OHG30112072701, G CODE OHG301ZZ2L737, L NO A31251124 — matching the nameplate serial A31251124 199 — dated 2019/09/27, 2.5 kg, MADE IN JAPAN.

Fitment notes

The 181 V three-phase input line pairs with Mitsubishi amplifiers of the 220 V class run from a 200–230 V supply; match the drive's rating table before ordering, and note that a brake motor wants an amplifier whose brake-output terminal drives the brake coil — wiring the brake across the motor supply is how brake rectifiers die young. Keep the CAPLUGS caps on until the connectors are crimped, since an open IP67 receptacle that has been sitting in a storeroom is no longer IP67 at the pins. For a braking comparison inside the same brand, the 60 mm-frame HC-MFS43 record from this series shows the brake-less small-frame approach, and the MR-J2S-100A amplifier article covers the classic pairing for this class.

Photos

Inspection video.

Related products on KOEED

Same family on the storefront: MITSUBISHI HF75S servo motor and the brake-less HF75S-A42 variant. Related reads: the HC-MFS43 servo motor and MR-J2S-100A amplifier records.