Siemens 1FK7081-2AF71-1QB0 SIMOTICS S 1FK7-CT 2.7 kW 12 Nm Holding Brake Servo Motor

The Siemens 1FK7081-2AF71-1QB0 is a SIMOTICS S 1FK7-CT synchronous servo motor rated 2.7 kW with 12 Nm standstill torque at 100K and a 3,000 rpm rated speed, built with an integrated holding brake. It runs on a 600 V DC link, uses natural cooling, and carries an IP64 enclosure with an absolute 20-bit single-turn DRIVE-CLiQ encoder (AS20DQI).

Technical Specifications

Selection Notes

The holding brake adds rotor mass, so inertia rises from the brakeless variant's 20.000 kgcm² to 23.500 kgcm² and shaft torsional stiffness drops from 109,000 to 76,000 Nm/rad — factor that into servo tuning if the axis needs high bandwidth. Choose this variant for vertical or gravity-loaded axes, where the brake holds the 12 Nm standstill torque during an E-stop or power loss instead of relying on the drive's active current. Rated current, speed, and power stay identical to the non-brake motor, so drive sizing does not change.

Applications

Typical use: vertical Z-axes, lift stations, and any DRIVE-CLiQ servo axis on SINAMICS S120/S210 where the load must not drop when power is removed.