8LT torque motors
High-torque 8LT motors
Three-phase synchronous motors from the 8LT 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.
- NdFeB permanent magnets
- Sinusoidal commutation with high resolution EnDat encoders as the feedback unit
- Now available with functional safety encoders
- Three-phase winding with star connection
- No elasticity in the power transmission system
- Minimum moment of inertia because of favorable rotor construction results in very good dynamic properties
- High overload capability/peak torque
- Low torque ripple
- No mechanical transfer elements that are subject to wear in the power transmission system, therefore high level of availability
- 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 50 Nm to 1020 Nm
- Connection using two SpeedTEC circular plugs
- Energy savings by reducing mechanical losses
- Control via ACOPOS servo drives or ACOPOSmulti drive systems
8LT 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 the 8LT 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 only has to optimize the speed and position controller. The integrated start-up environment in B&R Automation StudioTM provides assistance.
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
8LT three-phase synchronous motors with cooling type / construction A are self-cooling and are equipped with a ISO output flange. The motors must be installed on the cooling surface (flange).
8LT three-phase synchronous motors with cooling type / construction J are based on motors with cooling type A and are liquid-cooled. The liquid-cooling increases the rated torque (MN), rated current (IN), stall torque (M0) and stall current (I0) by 70% as compared to the respective motors with cooling type A.
8LT three-phase synchronous motors with cooling type / construction Q are self-cooling and have a shaft with a blind hole. The motors must be installed on the cooling surface (flange).
8LT three-phase synchronous motors with cooling type / construction S are based on motors with cooling type Q and are liquid-cooled. The liquid-cooling increases the rated torque (MN), rated current (IN), stall torque (M0) and stall current (I0) by 70% as compared to the respective motors with cooling type Q.
8LT three-phase synchronous motors are available in up to six different lengths. They have different power ratings with identical flange dimensions. The various lengths can be differentiated by a number (d) in the model number (3, 4, 5, 6, 7, 8).
- LengthAvailable for size9C3YesYes4YesYes5YesYes6YesYes7YesYes8---Yes
Feedback systems specified to meet your needs
8LT three-phase synchronous motors are equipped with high resolution EnDat Heidenhain encoders. A model is also available with multi-turn encoder. 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.
Load capacity of the shaft end and bearings
8LT three-phase synchronous motors are equipped with grooved ball bearings which are sealed on both sides and greased. The radial and axial forces (Fr , Fa) that occur on the shaft end during operation and installation must be within the specifications listed below. The bearing elements are not to be subjected to shocks or impacts! Incorrect handling will cause the lifespan of the bearings to be reduced or the bearing to be damaged.
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]Cooling type A, J, Q, S914500C31000
The radial force, Fr, on the shaft end is made up of the installation forces (e.g. belt tension on pulleys) and operational forces (e.g. load torque on the pinion). The maximum radial force Fr depends on the shaft end type, bearing type, average speed, position where the radial force is applied and the desired lifespan of the bearings.
Axial force, shift in shaft position caused by axial force
The axial force Fa on the shaft end is made up of the installation forces (e.g. stress caused by installation) and operational forces (e.g. thrust caused by slanted tooth pinions). The maximum axial force Fa depends on the bearing type and the desired lifespan 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.
Determining permissible values for Fr and Fa
Information to determine permissible values of Fr and Fa can be taken from the motor data for the respective three-phase synchronous motors. Permissible values are based on a bearing lifespan of 20,000 h (bearing lifespan calculation based on DIN ISO 281).
Depending on the cooling type and size, the 8LT three-phase synchronous motors are available
- with various rated speeds
- with or without oil seal
- with two different connection directions for the motor plug
The rated speed is indicated in the model number in the form of a 3-digit code (nnn). The code represents the rates speed divided by 100. If the rated speed is below 100 min-1, the "rated speed" part of the order code has an "A" as the first character and then the rated speed is listed like this: 800Umin-1 is shown in the code as A08.
The respective combination of other motor options is indicated in the model number in the form of a 2-digit code (ff).