8LS synchronous motors
8LS three-phase synchronous motors
Three-phase synchronous motors from the 8LS series are permanently excited, electronically commutated synchronous motors for applications that require excellent dynamic characteristics and positioning precision as well as compact size and reduced weight.
- Sinusoidal commutation with EnDat encoder or resolver as feedback unit
- Now available with functional safety encoders
- Three-phase winding with star connection
- Compact sizes result in low weight
- Minimum moment of inertia because of favorable rotor construction results in very good dynamic properties
- High overload capability/peak torque
- Optimized torque ripple
- High dynamic torque at high speeds
- Long life-span, all motor parts except for bearings are free of wear
- Power dissipation generated in the stator diverted directly to the flange via the housing
- Preloaded, grooved ball bearings which are sealed on both sides and greased
- Complete motor system with stall torque ranging from 0.2 Nm to 115 Nm
- Connection using two SpeedTEC circular plugs
- Control via ACOPOS servo drives or ACOPOSmulti drive systems
8LS three-phase synchronous motors are not allowed to be connected directly to the power mains; they are only allowed to be operated in combination with ACOPOS servo drives or ACOPOSmulti drive systems!
Embedded parameter chip
All relevant mechanical and electrical information and data is stored in the EnDat encoder used for 8LS three-phase synchronous motors. This means that the user doesn't have to configure settings on the servo drive in the field. As soon as the encoder is connected to the servo drive and the power is applied to the electronics, the motor is automatically identified. The motor sends its rated parameters and limit parameters to the servo drive. The drive then automatically determines the current limits and current control parameters required for optimal control of the motor. The user things that the user has to optimize are the speed and position controllers. The integrated commissioning environment in B&R Automation StudioTM provides all necessary support.
In addition to assistance during commissioning, routine service work is also simplified, and motors can be exchanged without having to take extra time to set parameters.
Cooling / construction type
Cooling type A
8LS three-phase synchronous motors with cooling type A are self-cooling and have a long, slim design. The motors must be installed on the cooling surface (flange).
Cooling type C
8LS three-phase synchronous motors with cooling type C are based on motors with cooling type A.
They are separately cooled and the only difference is a fan module mounted in the area of the B-side bearing.
The motors must be installed on the cooling surface (flange). The fan module increases the nominal torque (MN), nominal current (IN), stall torque (M0) and stall current (I0) by 30 % as compared to the respective motors with cooling type A.
8LS three-phase synchronous motors are available in seven different sizes (2 through 8). They have different dimensions (especially flange dimensions) and power ratings. These different sizes are indicated by a number represented by (c) in the model number. The larger the number, the larger the flange dimensions and power rating for the respective motor.
Cooling typeAvailable sizes2345678AYesYesYesYesYesYesYesC--YesYesYesYesYes
8LS three-phase synchronous motors are available in up to eight different lengths. They have different power ratings with identical flange dimensions. These different lengths are indicated by a number represented by (d) in the model number.
1)Only for cooling type C
Feedback systems specified to meet your needs
8LS three-phase synchronous motors are available with different encoder systems. As standard, they come equipped with Heidenhain EnDat encoders. Depending on the needs of the application, customers can select between normal and high-resolution encoders. Both types are also available as multi-turn encoders. They allow operation without requiring homing procedures or additional measurement systems on the workpiece. The absolute encoder functions without a battery and is therefore absolutely maintenance-free. For machines with lower precision and speed requirements, the 8LS three-phase synchronous motors are also available with resolvers.
Load capacity of the shaft end and bearings
8LS three-phase synchronous motors are equipped with grooved ball bearings which are sealed on both sides and greased. Radial and axial forces (Fr, Fa) applied to the shaft end during operation and installation must be within the specifications listed below. Bearing elements may not be subjected to shocks or impacts! Incorrect handling will reduce the service life and result in damage to the bearings.
The axial forces Fa permitted during the installation of pinion gears, couplings, etc. depend on the motor size and can be found in the following table:
Motor sizePermissible axial force Fa [N]Standard bearingSpecial motor option "Reinforced A side bearing"2850---31400---4230050505250095006250095007550095008950018700
The radial force Fr on the shaft end is a function of the loads during installation (e.g. belt tension on pulleys) and operation (e.g. load torque on the pinion). The maximum radial force Fr depends on the shaft end type, bearing type, average speed, the position where the radial force is applied and the desired service life of the bearings.
Axial force, shift in shaft position caused by axial force
The axial force Fa on the shaft end is a function of the loads during installation (e.g. stress caused by mounting) and operation (e.g. thrust caused by slanted tooth pinions). The maximum axial force Fa depends on the bearing type and the desired service life of the bearings. The fixed bearing is secured on the A flange with a retaining ring. The floating bearing is preloaded on the B flange with a spring in the direction of the A flange. Axial forces in the direction of the B flange can cause the spring bias to be overcome, which shifts the shaft by the amount of axial backlash in the bearing (approx. 0.1 - 0.2 mm). This shift can cause problems on motors with holding brakes or motors with EnDat encoders (EA and EB). As a result, no axial force is permitted in the direction of the B flange when using these motors.
Axial loads are not permitted on shaft ends of motors with holding brakes. It is especially important to prevent axial forces in the direction of the B flange since these forces can cause the brake to fail!
Determining permissible values for Fr and Fa
Information for determining permissible values of Fr and Fa can be found in the motor data for the respective three-phase synchronous motor. Permissible values are based on a bearing service life of 20,000 h (bearing service life calculation based on DIN ISO 281).
Depending on the cooling type, size and length, the 8LS three-phase synchronous motors can be delivered
- With various rated speeds
- With or without an oil seal
- With or without a holding brake
- with a reinforced holding brake
- With a smooth or keyed shaft
- With two different connection directions
The rated speed is listed as part of the model number in the form of a 3-digit code (nnn). This code represents the nominal speed divided by 100. The respective combination of other motor options is listed in the form of a 2-digit code (ff) as part of the model number.
Special motor options
8LS three-phase synchronous motors can be delivered with special motor option "reinforced A side bearing" depending on the cooling type, size and length: Other special motor options must be arranged with B&R.
The respective special motor option is listed as part of the model number in the form of a 2-digit code (gg).
8LS three-phase synchronous motors with special motor option "reinforced A side bearing" can handle increased radial and axial forces (Fr , Fa) on the end of the shaft. Information for determining permissible values of Fr and Fa can be found in the motor data for the respective 8LS three-phase synchronous motor.
Motors with special motor option "reinforced A side bearing" have increased values (in relation to motors with standard bearings) for the dimensions of the motor shaft, including the total length. The exact dimensions can be found in the motor data for the respective 8LS three-phase synchronous motors.