Product Description:

B & R Automation produces the 8MSA3S.R0-K4 as part of its 8MS Three Phase Synchronous Motors series. The unit is a three-phase permanent-magnet servo motor intended for position and velocity control in compact machinery where low load inertia and high rotational speeds are required. Self-cooling lets it operate without external airflow, and the S length combined with size 3 stator laminations keeps the housing compact for tight installation spaces. Its compact format suits small axes that need accurate motion without taking up much room.

The motor delivers a rated shaft speed of 6000 rpm while supplying 0.55 Nm of continuous torque, producing 0.35 kW of mechanical output at its nominal point. That operating point draws 0.83 A from the drive, which helps limit cable and inverter loading. When short bursts are demanded, the rotor can develop a peak torque of 2.6 Nm, and it can hold 0.65 Nm at stall without exceeding thermal limits. The electrical time constant is only 1.2 ms, so current settles quickly and supports responsive torque modulation during dynamic index moves. Installation tolerates up to 200 N of axial force on the shaft, and a resolver with BRX electronics supplies feedback; its nonlinearity is ±1 angular minute and its precision window is ±10 angular minutes, which supports accurate commutation. A rotor inertia of 0.39 kg cm² also supports fast acceleration on lightweight pick-and-place axes.

The stator resistance is 37.6 Ω, and the inductance is 45 mH, which set the electrical load seen by the drive. The torque constant is 0.71 Nm/A, linking commanded current to produced torque for current-loop tuning. The back-EMF voltage constant is 43 V/1000 rpm, so the motor returns voltage to the inverter during regeneration at higher speeds. These electrical values also affect how quickly current can rise in the windings during rapid speed changes.