Product Description:

B & R Automation’s 8MSA4S.R0-X3 belongs to the 8MS Three Phase Synchronous Motors series and is used as a compact servo actuator in industrial automation systems that require repeatable positioning and speed control. The motor has size code 4 with length code S, uses self-cooling to dissipate heat without external blowers, and integrates a resolver for feedback so drives can maintain precise phase alignment during dynamic cycles. This combination makes it suitable for motion tasks that need stable response in a compact motor package.

Rated operation is based on a nominal power of 0.90 kW, delivered at a shaft speed of 4500 rpm, where the electromagnetic design produces 1.9 Nm of continuous torque while drawing 2.25 A from the inverter. When rapid acceleration is required, the electromagnetic circuit can reach a peak torque of 10.4 Nm, which gives the axis additional short-term torque for changes in load or inertia. These values match a motor intended for compact machine-tool, packaging, and material-handling axes where precise speed and position control are required.

Beyond the continuous operating range, the rotor can hold a load statically with 2.6 Nm of stall torque, and each ampere of phase current produces 0.94 Nm/A, which supports current-based torque control. The magnetic circuit supports speeds up to 12000 rpm, with the upper limit influenced by mechanical balance and resolver bandwidth. Internally, the copper windings have a stator resistance of 4.55 Ω, which affects current flow and heat generation during pulse-width-modulated drive operation. A voltage constant of 57 V/1000 rpm provides the back EMF value used by the inverter, while the BRX resolver has ±1 angular minute nonlinearity and ±10 angular minutes of overall precision for rotor position feedback.