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Allen-Bradley MPL-B680F-SJ24AA Servo Motor — Detailed Product Specifications, Introduction, Applications, Advantages, and Model Comparison

1. Product Overview

The Allen-Bradley MPL-B680F-SJ24AA is a large-frame, low-inertia AC rotary servo motor in the MP-Series MPL low-inertia brushless servo motor family. It is designed for industrial motion-control systems that require high torque, fast dynamic response, accurate position feedback, and dependable mechanical holding capability.

This model uses a 215 mm frame, an approximately 203.2 mm (8.0 in.) magnetic stack, and a 3000 rpm rated-speed class. It combines approximately 60 N·m continuous stall torque with approximately 108.5 N·m peak stall torque, making it suitable for relatively demanding servo axes.

One of the most important characteristics of the MPL-B680F-SJ24AA is its single-turn high-resolution absolute encoder together with an integral 24 V DC brake. The keyed shaft and right-angle connector configuration also make it well suited to conventional industrial mechanical transmission systems.

The motor is intended to operate as part of a closed-loop servo system. In a typical installation, the servo drive regulates current and torque while receiving feedback from the motor encoder. The motion controller then uses this information to control speed, position, acceleration, deceleration, and overall machine movement.

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2. Basic Product Information

The specifications above describe the standard configuration class of the model. Actual installation characteristics can vary with product revision, connector arrangement, sealing configuration, cables, and machine installation conditions.

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3. Brand and Product Series

Brand

Allen-Bradley

Product Series

MP-Series

Motor Family

MPL Low-Inertia Brushless Servo Motors

The MPL series is built for applications where precise closed-loop motion is more important than simply providing continuous rotational power.

The motor is designed around a permanent-magnet brushless servo construction. This type of motor is well suited to applications requiring controlled acceleration, rapid deceleration, repeatable positioning, and accurate speed regulation.

The MPL-B680F-SJ24AA belongs to the larger end of the MPL family. Its 215 mm frame and 203.2 mm stack provide considerably more torque capability than the shorter B640F and B660F configurations.

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4. Model Number Interpretation

The model designation MPL-B680F-SJ24AA can be broadly understood as follows.

The most important configuration features are therefore:

3000 rpm + single-turn absolute feedback + keyed shaft + 24 V DC holding brake.

This combination is especially useful when the machine needs accurate absolute position within one motor revolution and also requires a motor-mounted holding brake.

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5. Detailed Technical Specifications

The 60.0 N·m continuous and 108.5 N·m peak torque values are consistent with the MPL-B680F motor family.

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6. Dimensions

The physical size of the MPL-B680F-SJ24AA is an important consideration because this is a large industrial servo motor.

The 215 mm frame dimension and 203.2 mm stack length describe the principal motor size. They should not be considered the complete machine installation envelope.

Additional space is required for the shaft coupling, connector, cables, cable bend radius, mounting hardware, and maintenance access.

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7. Weight

The motor itself is approximately 40.4 kg class, while packaging or shipping weight can be substantially higher.

For machine installation, the actual motor weight should be considered rather than the shipping weight.

Because the motor is relatively heavy, a suitable lifting and installation procedure should be used, particularly for vertical or overhead mounting.

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8. Torque Performance

The MPL-B680F-SJ24AA provides approximately 60 N·m of continuous stall torque and approximately 108.5 N·m of peak stall torque.

The continuous torque rating represents the motor’s sustained torque capability under appropriate operating and thermal conditions.

The peak torque rating is more relevant to short-duration events such as rapid acceleration, deceleration, indexing, and correction of transient load disturbances.

For example, a large rotary mechanism may require high torque while accelerating from zero to operating speed but require much less torque once the mechanism is rotating steadily.

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9. Speed and Power

The MPL-B680F-SJ24AA is a 3000 rpm-class servo motor with approximately 7.5 kW continuous rated output.

The 3000 rpm rating makes the motor suitable for applications where both substantial torque and relatively high rotational speed are required.

Compared with the 2000 rpm B680D family, the B680F is more suitable when machine speed is an important requirement.

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10. Single-Turn Absolute Feedback

The S configuration indicates single-turn absolute feedback.

The encoder provides high-resolution position information within one revolution of the motor shaft.

Single-turn absolute feedback is particularly useful for applications where the position within each motor revolution is important and the machine does not depend on multi-turn absolute position information.

Typical examples include:

• Rotary indexing.
• Servo-driven rollers.
• Rotary positioning.
• Machine-tool mechanisms.
• Packaging equipment.
• Printing and converting.
• Automated assembly.
• High-speed positioning axes.

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11. Single-Turn vs. Multi-Turn

When choosing between different MPL models, the difference between single-turn and multi-turn feedback can be very important.

The MPL-B680F-SJ24AA is therefore particularly attractive when the machine’s positioning requirement can be handled with single-turn absolute feedback.

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12. Integral 24 V DC Brake

One of the most important features of the MPL-B680F-SJ24AA is its integral 24 V DC holding brake.

The brake can be especially useful when the machine must prevent the motor shaft from moving after servo torque is removed.

This makes the model attractive for:

• Vertical servo axes.
• Z-axis mechanisms.
• Lifting equipment.
• Elevating platforms.
• Gravity-loaded mechanisms.
• Vertical transfer systems.
• Machines requiring controlled holding after shutdown.

The brake should not be considered a complete machine safety system by itself. The actual machine safety design needs to consider the load, gravity, emergency-stop requirements, mechanical energy, and required safe-state behavior.

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13. Brake Operating Considerations

The integrated brake is primarily intended for holding.

In normal operation, the servo drive should generally control acceleration and deceleration rather than using the mechanical brake as the primary dynamic stopping device.

A typical application therefore uses the servo system to bring the axis to the required position and then uses the brake when mechanical holding is required.

Important engineering considerations include:

• Brake release timing.
• Brake engagement timing.
• Servo torque during brake release.
• Vertical load.
• Mechanical inertia.
• Emergency-stop sequence.
• Brake wear.
• Brake control voltage.
• Machine safety requirements.

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14. Keyed Shaft

The MPL-B680F-SJ24AA uses a keyed shaft extension.

This is a conventional industrial mechanical interface that can be used with many types of power-transmission components.

Typical applications include:

• Flexible couplings.
• Gearboxes.
• Pulleys.
• Belt drives.
• Rollers.
• Ball-screw transmissions.
• Rotary indexing mechanisms.
• Mechanical transmission assemblies.

Correct shaft alignment is important. Misalignment can create excessive radial or axial forces and may reduce bearing life.

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15. Connector Configuration

The motor uses a circular bayonet connector configuration with a right-angle arrangement.

The connector configuration is designed to provide flexibility in industrial machine installation.

A right-angle connector can be useful when the motor is mounted close to:

• Machine frames.
• Guarding.
• Cabinet walls.
• Structural members.
• Other motors.
• Mechanical transmission components.

Cable routing should still allow adequate bending radius and maintenance access.

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16. IEC Metric Mounting

The MPL-B680F-SJ24AA uses IEC metric flange mounting.

A rigid mounting structure is particularly important for a high-performance servo motor.

During rapid acceleration and deceleration, the motor can generate fast torque changes. A flexible mounting structure can result in vibration, resonance, mechanical movement, or difficulty tuning the servo loop.

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17. Low-Inertia Construction

The MPL-B680F-SJ24AA is part of the low-inertia MPL family.

Its rotor inertia is approximately 0.00775 kg·m².

Low rotor inertia can be advantageous when a machine performs frequent acceleration and deceleration.

Typical motion patterns include:

Accelerate → position → stop → reverse → accelerate again.

A low-inertia motor can provide a responsive motor-side dynamic characteristic when it is properly matched to the mechanical load.

However, motor inertia is only one part of the system. Load inertia, gearbox ratio, coupling stiffness, friction, backlash, and transmission characteristics also affect servo performance.

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18. Main Product Advantages

18.1 High Continuous Torque

The approximately 60 N·m continuous torque class gives the MPL-B680F-SJ24AA enough capability for substantial industrial servo loads.

This makes it suitable for larger machine axes where smaller MPL motors may not provide enough continuous torque.

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18.2 Strong Peak Torque

The approximately 108.5 N·m peak torque capability provides useful short-duration torque reserve.

This can help during:

• Rapid acceleration.
• Rapid deceleration.
• Indexing.
• Direction reversal.
• Position correction.
• Load disturbance recovery.

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18.3 3000 rpm Speed Class

The 3000 rpm rating gives the motor useful speed capability without moving into an extremely high-speed motor class.

It is a practical choice for machines requiring both substantial torque and relatively fast rotational movement.

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18.4 Single-Turn Absolute Feedback

The high-resolution single-turn absolute encoder provides accurate position information within one motor revolution.

This is particularly useful for rotary positioning and indexing applications.

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18.5 Integral 24 V DC Brake

The built-in brake is one of the strongest reasons to choose the SJ24AA configuration.

It provides a motor-mounted holding function that is particularly useful for vertical or gravity-loaded mechanisms.

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18.6 Low-Inertia Rotor

The low-inertia construction supports responsive servo behavior when the motor is correctly matched to the load.

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18.7 Keyed Shaft

The keyed shaft provides a familiar mechanical interface for industrial power transmission systems.

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18.8 Large 215 mm Frame

The large frame provides the physical size required to achieve high torque output.

This makes the motor more suitable for demanding machinery than compact automation axes.

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18.9 Flexible Connector Arrangement

The right-angle connector arrangement can simplify cable routing and reduce installation-space problems.

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19. Typical Product Applications

Packaging Machinery

The motor is suitable for larger packaging-machine axes that require high torque, accurate positioning, and controlled acceleration.

Possible uses include:

• Heavy indexing axes.
• Feeding mechanisms.
• Large rotary positioning units.
• Packaging conveyors.
• Product transfer mechanisms.
• Film handling.

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Automated Assembly

Automated assembly systems can require fast and repeatable movement.

The motor can be used for large servo axes where high torque and accurate position feedback are necessary.

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Material Handling

The motor can be considered for demanding material-handling equipment.

Examples include:

• Heavy transfer axes.
• Conveyor systems.
• Positioning mechanisms.
• Automated storage equipment.
• Large indexing systems.

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Vertical Servo Axes

The integral brake makes the MPL-B680F-SJ24AA particularly attractive for vertical applications.

Potential uses include:

• Z-axis mechanisms.
• Lifting platforms.
• Vertical transfer equipment.
• Elevating machinery.
• Gravity-loaded positioning systems.

The actual brake sizing and safety arrangement should be evaluated against the load and machine design.

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Machine Tools

The motor can be used for certain machine-tool axes where 3000 rpm, approximately 60 N·m continuous torque, and single-turn absolute feedback are appropriate.

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Printing and Converting

Printing, coating, converting, and material-processing equipment often requires accurate servo control and stable speed regulation.

The 3000 rpm class gives the motor useful flexibility for rotary processing axes.

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Rotary Indexing

Rotary indexing machines can benefit from the motor’s high peak torque capability.

The motor can accelerate a large mechanism, position it accurately, and use the integral brake where holding capability is required.

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20. Application Suitability

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21. Five Closely Related MPL Models

The following models are useful comparisons because they belong to the same MPL family or share a very similar motor configuration.

The MPL-B680F-SJ72AA is the closest no-brake counterpart.

The MPL-B680F-MJ24AA is a useful comparison when the machine requires multi-turn absolute feedback instead of single-turn feedback.

The MPL-B680D-SJ24AA is appropriate for comparing the same single-turn/brake concept at a lower 2000 rpm speed class.

The MPL-B680H-SJ24AA provides a comparison with the higher 3500 rpm speed class.

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22. Five Same-Brand Commonly Compared Models

These five models provide a useful comparison range from shorter-stack motors to the larger B680 family.

The B640F is the lighter and lower-torque option.

The B660F occupies the middle position.

The B680F provides the longest 203.2 mm stack in this comparison and approximately 60 N·m continuous torque class.

The B680D offers a lower speed but higher torque-oriented performance.

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23. B640F vs. B660F vs. B680F

The frame size is similar among these models, but the stack length changes substantially.

This provides a simple way to understand the physical and torque progression:

B640F → B660F → B680F

As the stack becomes longer, the motor becomes physically larger and heavier while offering greater torque capability.

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24. MPL-B680F-SJ24AA vs. MPL-B680F-SJ72AA

These are among the closest model comparisons.

The main difference is the integral brake.

If the machine requires motor-mounted holding capability, the MPL-B680F-SJ24AA is the more suitable configuration.

If no motor brake is required, the MPL-B680F-SJ72AA is the simpler configuration.

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25. MPL-B680F-SJ24AA vs. MPL-B680F-MJ24AA

These models are mechanically very similar but use different feedback configurations.

The selection is primarily based on the feedback requirement.

For a rotary mechanism where one-revolution absolute position is sufficient, the SJ24AA configuration can be a good fit.

For applications involving extensive multi-revolution travel, the multi-turn MJ24AA configuration can be more appropriate.

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26. MPL-B680F-SJ24AA vs. MPL-B680D-SJ24AA

These models share the single-turn feedback and brake configuration but have different speed classes.

The B680F is the better fit when 3000 rpm operation is important.

The B680D is more attractive when the application is torque-oriented and does not require the higher speed class.

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27. MPL-B680F-SJ24AA vs. MPL-B680H-SJ24AA

The H configuration moves toward higher rotational speed.

The F model offers a balanced 3000 rpm configuration.

The H model is more appropriate when the machine benefits from the higher 3500 rpm speed class.

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28. Why the MPL-B680F-SJ24AA Is Attractive for Vertical Axes

The combination of large-frame torque + 3000 rpm + single-turn absolute feedback + integral 24 V DC brake makes this model particularly interesting for vertical servo applications.

For example, consider a vertical positioning axis.

The motor may need enough continuous torque to support the mechanism during operation.

During acceleration, it may require additional peak torque.

The encoder provides the feedback required for servo positioning.

When the axis reaches its required position, the holding brake can provide mechanical holding capability where the machine design calls for it.

This combination makes the model a practical candidate for:

• Vertical transfer machines.
• Z-axis positioning.
• Lifting mechanisms.
• Elevating platforms.
• Vertical indexing equipment.
• Gravity-loaded automation systems.

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29. Important Consideration: Single-Turn Feedback

The single-turn configuration is not necessarily a disadvantage.

It depends entirely on the machine.

For rotary applications where the important position information is the position within one revolution, single-turn absolute feedback can be perfectly appropriate.

Examples include:

• Rotary indexing.
• Servo rollers.
• Rotary tables.
• Positioning spindles.
• Packaging rollers.
• Rotary processing equipment.

For long-travel axes where the motor rotates many revolutions and absolute multi-turn position is important, a multi-turn MPL configuration may be a better choice.

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30. Installation Considerations

Because the motor weighs approximately 40.4 kg and has a 215 mm frame, mechanical installation should be planned carefully.

The mounting plate should have adequate stiffness.

The shaft coupling should be aligned accurately.

The motor should have sufficient clearance around the connector and cables.

The brake wiring should be routed separately and correctly according to the servo system design.

The motor should not be installed in an environment that exceeds its specified thermal conditions.

For vertical mounting, the machine structure should be capable of supporting the motor and load independently of servo torque.

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31. Servo Drive Matching

The motor should be paired with a compatible servo drive capable of handling:

• 460 V-class motor operation.
• Continuous motor current.
• Peak motor current.
• Encoder feedback.
• Brake control.
• Required speed.
• Required torque.
• Required acceleration.
• Required deceleration.

The approximate continuous stall current is 48 A, while the peak stall current is approximately 96 A for the B680F motor family.

Drive selection should be based on the actual operating duty rather than simply selecting a drive based on nominal motor horsepower.

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32. Load Inertia and Servo Tuning

The low-inertia design is valuable, but the motor must still be matched to the mechanical load.

Engineers should evaluate:

• Motor rotor inertia.
• Load inertia.
• Gear ratio.
• Screw ratio.
• Pulley ratio.
• Coupling stiffness.
• Mechanical friction.
• Backlash.
• Required acceleration.
• Required deceleration.
• Positioning accuracy.
• Settling time.

A large load with a relatively low-inertia motor can still produce a challenging servo-tuning problem.

The best servo performance normally comes from considering the complete mechanical system rather than selecting the motor solely from its torque rating.

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33. Maintenance

Routine maintenance should focus on the entire mechanical and electrical system.

Important inspection points include:

• Motor mounting bolts.
• Shaft coupling.
• Mechanical alignment.
• Cable condition.
• Connector condition.
• Encoder feedback.
• Motor temperature.
• Abnormal vibration.
• Bearing noise.
• Brake operation.
• Mechanical backlash.

The brake deserves additional attention because repeated engagement and release can gradually affect its mechanical condition.

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34. Recommended Selection Guide

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35. Final Technical Summary

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36. Overall Product Evaluation

The Allen-Bradley MPL-B680F-SJ24AA is a substantial industrial servo motor designed for demanding motion-control applications.

Its combination of 60 N·m continuous stall torque, 108.5 N·m peak stall torque, 7.5 kW rated output, 3000 rpm operation, low rotor inertia, single-turn high-resolution absolute feedback, keyed shaft, and integral 24 V DC brake gives it a well-balanced configuration for large servo axes.

The 215 mm frame and 203.2 mm stack place the motor in the larger MPL size range. This provides the torque capacity needed for heavy industrial mechanisms while maintaining the dynamic characteristics expected from a low-inertia servo motor.

The single-turn absolute encoder makes the model particularly suitable for rotary positioning and indexing applications. When the machine does not require multi-turn absolute position information, this configuration can be a straightforward and effective choice.

The 24 V DC integral brake is another major advantage. It makes the motor especially useful for vertical axes and other mechanisms where mechanical holding is required after the servo motor stops producing torque.

Compared with the MPL-B680F-SJ72AA, the SJ24AA adds the integral brake. Compared with the MPL-B680F-MJ24AA, it uses single-turn rather than multi-turn absolute feedback. Compared with the MPL-B680D-SJ24AA, it provides a higher 3000 rpm speed class while sacrificing some of the lower-speed model’s higher peak-torque capability.

Overall, the MPL-B680F-SJ24AA can be considered a large-frame, high-torque, 3000 rpm-class, single-turn absolute servo motor with an integral 24 V DC holding brake. It is particularly well suited to vertical positioning, rotary indexing, packaging machinery, material handling, machine tools, printing and converting equipment, and other industrial automation systems where substantial servo torque and mechanical holding capability are required.