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.
- Also available with hollow shaft
- Sinusoidal commutation with high resolution EnDat encoders as the feedback unit
- 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
- When used as a direct drive: 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 993 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 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
8LT three-phase synchronous motors with cooling / construction type 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/construction type B are self-cooling hollow shaft motors.
8LT three-phase synchronous motors with cooling / construction type J are based on motors with cooling type A and are liquid-cooled. The liquid-cooling increases the nominal torque (MN), nominal 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 / construction type K are based on motors with cooling type B and are liquid-cooled.
8LT three-phase synchronous motors with cooling / construction type 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 / construction type S are based on motors with cooling type Q and are liquid-cooled. The liquid-cooling increases the nominal torque (MN), nominal 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 size9C1)3Yes1)Yes4YesYes5YesYes6YesYes7YesYes8---Yes
- 1)Not for 8LTB/8LTK
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. 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 correspond to the values in the "Shaft load" diagram (see "Technical data" section).
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.
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).
8LT three-phase synchronous motors can be delivered with the following options depending on the cooling type and size:
- With various rated speeds
- With or without an oil seal
- with two different connection directions for the motor connector
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. If the rated speed is below 100 rpm, the "rated speed" part of the order code has an "A" as the first character and then the rated speed is listed as follows. A speed of 80 rpm corresponds to A08.
The respective combination of other motor options is listed in the form of a 2-digit code (ff) as part of the model number.