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Allen-Bradley MPL-B320P-RJ72AA Servo Motor – Detailed Specifications, Applications, Advantages and Related Models
1. Product Introduction
The Allen-Bradley MPL-B320P-RJ72AA is a low-inertia brushless AC rotary servo motor designed for high-speed industrial motion-control applications. It belongs to the MP-Series MPL family and uses a 100 mm frame, 50.8 mm magnetic stack, 5000 RPM speed rating, resolver feedback, keyed shaft, SpeedTEC DIN right-angle connector, and no integral brake.
This motor is intended for machinery that requires controlled acceleration, accurate positioning, repeatable motion, and reliable closed-loop speed and torque control. Its low-inertia design allows the motor to respond quickly to changes in the commanded motion profile.
The RJ72AA configuration is particularly useful when a machine requires a keyed shaft and resolver feedback without an integrated holding brake. This configuration is therefore different from the closely related MJ72AA model, which uses multi-turn high-resolution absolute feedback, and from RJ74AA, which adds a 24 V DC brake.
The motor has a rated output of approximately 1.5 kW, a rated speed of 5000 RPM, and approximately 3.05 N·m continuous torque. The B320P motor family has approximately 7.91 N·m peak torque and a rotor inertia of approximately 0.000078 kg·m².
2. Basic Product Parameters
| Parameter | Specification |
|---|---|
| Model | MPL-B320P-RJ72AA |
| Brand | Allen-Bradley |
| Product Type | AC Rotary Servo Motor |
| Motor Type | Low-Inertia Brushless Servo Motor |
| Product Series | MP-Series MPL |
| Voltage Class | 460 V AC class |
| Product Supply Rating | 480 V AC |
| Rated Power | 1.5 kW |
| Rated Speed | 5000 RPM |
| Maximum Speed | 5000 RPM |
| Continuous Torque | 3.05 N·m |
| Peak Torque | 7.91 N·m |
| Frame Size | 100 mm |
| Magnet Stack Length | 50.8 mm |
| Feedback | Resolver |
| Shaft Type | Keyed Shaft Extension |
| Shaft Seal | No Shaft Seal |
| Brake | No Integral Brake |
| Connector | SpeedTEC DIN |
| Connector Style | Right-Angle |
| Connector Rotation | 180° Rotatable |
| Mounting | IEC Metric Flange |
| Mounting Holes | Free Mounting Holes, Type FF |
| Rotor Inertia | Approx. 0.000078 kg·m² |
| Duty | S1 |
| Approx. Dimensions | 42.799 × 21.692 × 26.01 cm |
| Approx. Weight | 3.85 kg |
The exact product description identifies the RJ72AA as a 460 V-class, 100 mm-frame, 50.8 mm-stack, 5000 RPM servo motor using resolver feedback, a keyed shaft extension, SpeedTEC DIN right-angle connector, and no brake.
The published weight is around 3.85 kg, while broader B320P motor-family data lists approximately 3.7 kg. For catalog-level product identification, approximately 3.85 kg is a practical reference for the RJ72AA configuration.
3. Brand
Brand: Allen-Bradley
The MPL-B320P-RJ72AA is an Allen-Bradley industrial servo motor intended for integration into automated machinery and motion-control systems.
The product is part of the Allen-Bradley MP-Series motion-control product family.
4. Product Series
Series: MP-Series MPL Low-Inertia Brushless Servo Motors
The MPL series is designed for industrial applications requiring fast dynamic response, accurate motion control, and repeatable positioning.
The low-inertia design is especially useful for machines that repeatedly accelerate, decelerate, stop, reverse, and reposition.
The B320P configuration belongs to the 5000 RPM class and provides approximately 1.5 kW output, 3.05 N·m continuous torque, and 7.91 N·m peak torque.
5. Model Number Explanation
The model number contains several configuration identifiers.
| Model Code | Meaning |
|---|---|
| MPL | Low-inertia brushless servo motor family |
| B | 460 V-class motor family |
| 3 | 100 mm frame class |
| 20 | 50.8 mm magnet stack |
| P | 5000 RPM speed class |
| R | Resolver feedback |
| J | Keyed shaft extension |
| 7 | SpeedTEC DIN right-angle connector, 180° rotatable |
| 2 | No integral brake |
| AA | Standard catalog configuration |
The model code is useful when comparing closely related MPL motors.
For example, the RJ72AA uses resolver feedback, a keyed shaft, and no brake.
An RJ74AA uses the same general resolver/keyed configuration but adds a 24 V DC brake.
An RK72AA changes the shaft from keyed to keyless while retaining resolver feedback and no brake.
6. Detailed Technical Specifications
| Technical Parameter | Specification |
|---|---|
| Model | MPL-B320P-RJ72AA |
| Product Category | Servo Motor |
| Motor Construction | Low-Inertia Brushless |
| Motor Type | Rotary AC Servo |
| Voltage Class | 460 V AC |
| Product Rating | 480 V AC |
| Rated Output | 1.5 kW |
| Rated Speed | 5000 RPM |
| Maximum Speed | 5000 RPM |
| Continuous Torque | 3.05 N·m |
| Peak Torque | 7.91 N·m |
| Frame Size | 100 mm |
| Stack Length | 50.8 mm |
| Feedback | Resolver |
| Shaft | Keyed |
| Brake | None |
| Connector | SpeedTEC DIN |
| Connector Position | Right-angle |
| Connector Rotation | 180° |
| Mounting | IEC Metric |
| Mounting Holes | Type FF, Free Mounting Holes |
| Rotor Inertia | Approx. 0.000078 kg·m² |
| Duty Cycle | S1 |
| Operating Temperature Reference | 0–40 °C |
| Approx. Dimensions | 42.799 × 21.692 × 26.01 cm |
| Approx. Weight | 3.85 kg |
The 1.5 kW, 5000 RPM and 3.05 N·m ratings are consistent with the B320P motor family specifications.
7. Motor Power
The MPL-B320P-RJ72AA provides approximately 1.5 kW of rated motor output.
This power level places the motor in a useful range for medium-duty industrial motion applications.
Unlike a conventional fixed-speed AC motor, the servo motor is intended to operate as part of a closed-loop motion system.
The servo drive controls the motor according to the required position, velocity, acceleration, and torque profile.
This makes the motor suitable for applications where simple continuous rotation is not enough and the machine requires controlled dynamic movement.
8. 5000 RPM High-Speed Operation
The MPL-B320P-RJ72AA has a 5000 RPM rated speed and a 5000 RPM maximum speed.
This makes it suitable for machinery that requires rapid rotary movement.
High-speed operation can be useful for:
- High-cycle packaging machines
- Rotary indexing systems
- Conveyor positioning
- Feeding mechanisms
- Printing equipment
- Labeling equipment
- Assembly machinery
- Automated material handling
- High-speed positioning systems
The actual operating speed should always be determined by the mechanical load, servo-drive configuration, coupling, bearings, duty cycle, and application requirements.
9. Continuous Torque
The continuous torque rating is approximately 3.05 N·m.
Continuous torque represents the torque that the motor can produce under appropriate continuous operating conditions.
| Torque Parameter | Specification |
|---|---|
| Model | MPL-B320P-RJ72AA |
| Rated Power | 1.5 kW |
| Rated Speed | 5000 RPM |
| Continuous Torque | 3.05 N·m |
| Peak Torque | 7.91 N·m |
| Rotor Inertia | 0.000078 kg·m² |
| Frame Size | 100 mm |
| Stack Length | 50.8 mm |
| Weight | Approx. 3.85 kg |
| Dimensions | Approx. 42.799 × 21.692 × 26.01 cm |
For motor sizing, continuous torque should not be considered by itself.
The machine’s acceleration torque, friction torque, load inertia, transmission efficiency, duty cycle, and peak torque requirements should also be considered.
10. Peak Torque
The B320P motor family provides approximately 7.91 N·m peak torque.
Peak torque is particularly important during rapid acceleration and deceleration.
A machine may require relatively little torque during steady-state operation but considerably more torque during a short acceleration period.
The servo system can use this additional torque capability to produce rapid changes in motor speed.
The actual allowable peak torque duration depends on the complete servo system and operating conditions.
11. Low-Inertia Design
The rotor inertia of the B320P configuration is approximately 0.000078 kg·m².
Low rotor inertia is an important feature of this servo motor.
When the rotating mass has relatively low inertia, the motor can change speed quickly when the servo drive changes the commanded torque.
This is useful for applications involving:
- Frequent indexing
- Rapid positioning
- Repeated acceleration
- Repeated deceleration
- Direction changes
- Short machine cycles
- Coordinated multi-axis movement
A low-inertia motor is particularly useful when the motor and load inertia are properly matched.
12. Resolver Feedback
One of the most important characteristics of the RJ72AA configuration is its resolver feedback.
The resolver provides rotor-position information to the servo control system.
This allows the drive to operate the motor as a closed-loop servo system.
The resolver configuration also distinguishes the RJ72AA from other B320P configurations that use different feedback technologies.
| Feedback Parameter | Specification |
|---|---|
| Model | MPL-B320P-RJ72AA |
| Feedback Type | Resolver |
| Feedback Category | Rotary position feedback |
| Motor Speed | 5000 RPM |
| Rated Power | 1.5 kW |
| Continuous Torque | 3.05 N·m |
| Peak Torque | 7.91 N·m |
| Shaft | Keyed |
| Brake | None |
| Weight | Approx. 3.85 kg |
| Dimensions | Approx. 42.799 × 21.692 × 26.01 cm |
Resolver feedback is commonly used in industrial servo systems where reliable rotor-position information is required.
13. Resolver Feedback vs. Absolute Encoder Configurations
The RJ72AA should not be treated as electrically identical to an MPL-B320P-MJ72AA.
The two models use different feedback technologies.
| Feature | MPL-B320P-RJ72AA | MPL-B320P-MJ72AA |
|---|---|---|
| Motor Family | B320P | B320P |
| Power | 1.5 kW | 1.5 kW |
| Speed | 5000 RPM | 5000 RPM |
| Continuous Torque | 3.05 N·m | 3.05 N·m |
| Feedback | Resolver | Multi-turn high-resolution absolute |
| Shaft | Keyed | Keyed |
| Brake | No | No |
| Frame | 100 mm | 100 mm |
| Stack | 50.8 mm | 50.8 mm |
| Weight | Approx. 3.85 kg | Configuration dependent |
| Dimensions | Approx. 42.799 × 21.692 × 26.01 cm | B320P family envelope |
When replacing one with the other, the feedback compatibility of the servo drive and controller must be checked.
14. Keyed Shaft
The J designation indicates a keyed shaft extension.
The keyed shaft is designed for mechanical coupling arrangements that use a conventional shaft key.
This can be useful when the existing machine transmission uses a keyed coupling, pulley, sprocket, or other compatible mechanical connection.
| Mechanical Parameter | Specification |
|---|---|
| Model | MPL-B320P-RJ72AA |
| Shaft Type | Keyed Shaft |
| Shaft Key | Yes |
| Shaft Seal | No Shaft Seal |
| Frame | 100 mm |
| Stack | 50.8 mm |
| Mounting | IEC Metric Flange |
| Brake | None |
| Connector | SpeedTEC DIN |
| Weight | Approx. 3.85 kg |
| Dimensions | Approx. 42.799 × 21.692 × 26.01 cm |
The shaft coupling must be selected according to the motor’s speed, torque, radial load, axial load, and machine operating conditions.
15. No Integral Brake
The RJ72AA is a no-brake configuration.
This means that the motor does not include the integral 24 V DC holding brake found on related “74AA” configurations.
The absence of a brake is useful in applications where the machine does not require motor-mounted holding capability.
Typical examples include horizontal rotary axes, conveyors, rotary indexing systems, and machine mechanisms where an external holding arrangement is not required.
For vertical axes or gravity-loaded mechanisms, the machine designer must determine whether a separate holding mechanism or brake-equipped motor is necessary.
16. SpeedTEC DIN Connector
The motor uses a SpeedTEC DIN right-angle connector.
The connector is approximately 180 degrees rotatable, providing flexibility during installation.
This can be useful in compact machinery where cable routing space is limited.
The right-angle configuration can help keep cables close to the machine structure and away from moving components.
| Connector Parameter | Specification |
|---|---|
| Model | MPL-B320P-RJ72AA |
| Connector Type | SpeedTEC DIN |
| Configuration | Right-angle |
| Rotation | 180° rotatable |
| Feedback | Resolver |
| Brake Connection | Not applicable |
| Shaft | Keyed |
| Weight | Approx. 3.85 kg |
| Dimensions | Approx. 42.799 × 21.692 × 26.01 cm |
17. Mechanical Dimensions
The motor uses a 100 mm frame and 50.8 mm magnetic stack.
The approximate overall product dimensions are:
- Length: 42.799 cm
- Width: 21.692 cm
- Height: 26.01 cm
| Mechanical Dimension | Specification |
|---|---|
| Model | MPL-B320P-RJ72AA |
| Frame Size | 100 mm |
| Magnet Stack | 50.8 mm |
| Overall Length | Approx. 42.799 cm |
| Overall Width | Approx. 21.692 cm |
| Overall Height | Approx. 26.01 cm |
| Mounting | IEC Metric Flange |
| Mounting Holes | Free Mounting Holes, Type FF |
| Shaft | Keyed |
| Connector | Right-angle SpeedTEC DIN |
| Brake | None |
| Weight | Approx. 3.85 kg |
These dimensions should be used as general product-envelope information.
For final machine design, the detailed mechanical drawing should be checked for shaft dimensions, mounting-hole locations, connector clearance, coupling clearance, and installation tolerances.
18. Weight
The listed product weight is approximately 3.85 kg.
Some B320P family documentation lists the motor family weight at approximately 3.7 kg, so minor differences can occur depending on configuration, documentation revision, and whether the stated value represents motor-only or packaged weight.
For the RJ72AA configuration, approximately 3.85 kg is a useful catalog reference.
| Weight Parameter | Specification |
|---|---|
| Model | MPL-B320P-RJ72AA |
| Approx. Motor Weight | 3.85 kg |
| Frame Size | 100 mm |
| Stack Length | 50.8 mm |
| Rated Power | 1.5 kW |
| Rated Speed | 5000 RPM |
| Continuous Torque | 3.05 N·m |
| Peak Torque | 7.91 N·m |
| Dimensions | Approx. 42.799 × 21.692 × 26.01 cm |
19. Electrical Parameters
| Electrical Parameter | Specification |
|---|---|
| Model | MPL-B320P-RJ72AA |
| Motor Type | Brushless AC Servo |
| Voltage Class | 460 V AC |
| Product Rating | 480 V AC |
| Rated Power | 1.5 kW |
| Rated Speed | 5000 RPM |
| Maximum Speed | 5000 RPM |
| Continuous Torque | 3.05 N·m |
| Peak Torque | 7.91 N·m |
| Feedback | Resolver |
| Shaft | Keyed |
| Brake | No Brake |
| Rotor Inertia | Approx. 0.000078 kg·m² |
| Connector | SpeedTEC DIN |
| Mounting | IEC Metric |
| Weight | Approx. 3.85 kg |
| Dimensions | Approx. 42.799 × 21.692 × 26.01 cm |
20. Typical Applications
Packaging Machinery
Packaging machines frequently require fast indexing and repeatable positioning.
The 5000 RPM motor can be used for rotary indexing, feeding mechanisms, synchronized motion, cutting systems, and other controlled machine functions.
The low-inertia rotor is useful when the machine repeatedly accelerates and decelerates.
Conveyor Positioning
Servo-controlled conveyors can require precise speed control and accurate positioning.
The MPL-B320P-RJ72AA can be used where the conveyor needs controlled acceleration, deceleration, indexing, or synchronization with another machine axis.
Pick-and-Place Machinery
Pick-and-place systems frequently require rapid movements between defined positions.
The motor’s low-inertia characteristics can help support fast response.
The resolver provides position feedback for closed-loop servo operation.
Assembly Equipment
Automated assembly machinery may use servo motors for rotary indexing, component positioning, transfer mechanisms, and controlled actuator movement.
The B320P’s 1.5 kW power level can be appropriate for a range of medium-duty machine axes.
Printing Machinery
Printing equipment can require synchronized rotary movement.
Servo motors can be used to control rollers, feeders, positioning mechanisms, and other machine components where accurate speed control is important.
Labeling Machines
Labeling systems often require rapid and repeatable movement.
The 5000 RPM motor can support high-cycle operation when the load and transmission are correctly matched.
Material Handling
Material-handling machinery may use servo motors for positioning, sorting, transfer, and indexing.
The no-brake configuration is useful where the machine does not require an integrated holding brake.
Machine Tools
The motor can be used for selected auxiliary axes, positioning systems, indexing mechanisms, and other controlled machine-tool functions.
The final selection depends on required torque, speed, inertia, acceleration, and duty cycle.
21. Main Product Advantages
21.1 High-Speed 5000 RPM Operation
The 5000 RPM speed rating provides the motor with sufficient speed for many high-cycle machine applications.
This is particularly useful where rapid rotary movement is required.
21.2 Low-Inertia Response
The low rotor inertia allows the motor to change speed quickly.
This supports applications involving frequent acceleration, deceleration, and direction changes.
21.3 Resolver Feedback
The resolver provides reliable rotor-position feedback for closed-loop servo operation.
This allows the servo drive to monitor motor position and coordinate motor torque with the required motion profile.
21.4 Keyed Shaft
The keyed shaft makes the motor suitable for conventional keyed mechanical connections.
This can simplify integration when replacing an existing keyed-shaft servo motor.
21.5 No-Brake Configuration
The no-brake configuration is useful where a motor-mounted holding brake is unnecessary.
It is particularly suitable for many horizontal axes.
21.6 Compact 100 mm Frame
The 100 mm frame provides a relatively compact package for a 1.5 kW, 5000 RPM servo motor.
This can be useful when machine installation space is limited.
21.7 Rotatable Right-Angle Connector
The right-angle SpeedTEC DIN connector can be rotated through approximately 180 degrees.
This allows the installer to select a suitable cable direction and can make machine integration easier.
22. Applications Where the RJ72AA Is Particularly Suitable
The RJ72AA configuration is useful where the following characteristics are required:
- 460 V-class servo motor
- 1.5 kW output
- 5000 RPM speed
- 3.05 N·m continuous torque
- Resolver feedback
- Keyed shaft
- No integral brake
- 100 mm frame
- 50.8 mm stack
- Right-angle DIN connector
This makes the model a practical choice for horizontal rotary axes and other machine mechanisms where a keyed mechanical connection is preferred and a motor-mounted brake is not necessary.
23. Applications Where a Brake-Equipped Model May Be More Appropriate
A no-brake motor is not automatically the correct configuration for every machine.
For vertical axes, lifting systems, or gravity-loaded mechanisms, the machine may require a holding brake.
In such cases, a related “74AA” configuration can be considered.
| Application Requirement | Possible Configuration |
|---|---|
| Keyed shaft + resolver + no brake | MPL-B320P-RJ72AA |
| Keyed shaft + resolver + 24 V DC brake | MPL-B320P-RJ74AA |
| Keyless shaft + resolver + no brake | MPL-B320P-RK72AA |
| Keyless shaft + resolver + 24 V DC brake | MPL-B320P-RK74AA |
| Keyed shaft + multi-turn absolute + no brake | MPL-B320P-MJ72AA |
| Keyed shaft + multi-turn absolute + brake | MPL-B320P-MJ74AA |
24. Installation Considerations
The motor should be mounted on a rigid machine structure.
The mounting surface should be properly aligned and capable of handling the reaction forces generated during acceleration and deceleration.
The motor shaft and driven shaft should be aligned accurately.
Incorrect alignment can increase radial and axial loading and may reduce coupling and bearing life.
The keyed coupling should be properly selected for the motor’s speed and torque.
25. Cable Routing
Servo power and feedback cables should be routed carefully.
Power cables should be kept away from sensitive signal wiring where practical.
Cables should not be exposed to excessive mechanical tension, sharp bends, abrasion, or repeated movement beyond their specified capabilities.
The right-angle connector can be rotated to improve cable routing, but the connector should not be repeatedly repositioned without a practical installation reason.
26. Servo Tuning
The motor’s mechanical characteristics are only one part of the complete servo system.
The drive must be correctly configured for the motor and feedback system.
Important tuning factors include:
- Load inertia
- Motor inertia
- Gear ratio
- Coupling stiffness
- Mechanical backlash
- Friction
- Acceleration
- Deceleration
- Position-loop response
- Velocity-loop response
- Resonance
- Following error
Because the motor is designed for high-speed operation, correct tuning is especially important in applications with rapid acceleration and deceleration.
27. Maintenance
Routine inspection should include:
- Motor mounting
- Shaft coupling
- Motor cables
- Feedback connector
- Power connector
- Mechanical alignment
- Abnormal vibration
- Abnormal noise
- Motor temperature
The keyed shaft and coupling should be checked periodically.
If the machine begins to exhibit unexpected vibration or positioning error, the motor should not automatically be assumed to be the cause.
Mechanical backlash, coupling problems, load changes, bearings, and servo tuning can also create similar symptoms.
28. Replacement Considerations
When replacing an existing motor, the complete catalog number should be checked.
Matching only the B320P family is not sufficient.
The following characteristics should all be verified:
| Replacement Parameter | RJ72AA Specification |
|---|---|
| Model | MPL-B320P-RJ72AA |
| Voltage | 460 V class |
| Power | 1.5 kW |
| Speed | 5000 RPM |
| Feedback | Resolver |
| Shaft | Keyed |
| Brake | None |
| Frame | 100 mm |
| Stack | 50.8 mm |
| Connector | SpeedTEC DIN |
| Mounting | IEC Metric |
| Rotor Inertia | 0.000078 kg·m² |
| Weight | Approx. 3.85 kg |
| Dimensions | Approx. 42.799 × 21.692 × 26.01 cm |
Feedback compatibility is particularly important.
A resolver-feedback motor should not be treated as directly interchangeable with a motor using an absolute encoder unless the servo-drive system supports the different feedback configuration.
29. Five Closely Related Models
The following five models are closely related to the MPL-B320P-RJ72AA.
| Model | Voltage | Frame | Stack | Speed | Power | Continuous Torque | Feedback | Shaft | Brake | Approx. Weight | Dimensions |
|---|---|---|---|---|---|---|---|---|---|---|---|
| MPL-B320P-RJ72AA | 460 V class | 100 mm | 50.8 mm | 5000 RPM | 1.5 kW | 3.05 N·m | Resolver | Keyed | No | 3.85 kg | 42.799 × 21.692 × 26.01 cm |
| MPL-B320P-RJ74AA | 460 V class | 100 mm | 50.8 mm | 5000 RPM | 1.5 kW | 3.05 N·m | Resolver | Keyed | 24 V DC | Verify exact unit | B320P family envelope |
| MPL-B320P-RK72AA | 460 V class | 100 mm | 50.8 mm | 5000 RPM | 1.5 kW | 3.05 N·m | Resolver | Keyless | No | Verify exact unit | B320P family envelope |
| MPL-B320P-RK74AA | 460 V class | 100 mm | 50.8 mm | 5000 RPM | 1.5 kW | 3.05 N·m | Resolver | Keyless | 24 V DC | Verify exact unit | B320P family envelope |
| MPL-B320P-MJ72AA | 460 V class | 100 mm | 50.8 mm | 5000 RPM | 1.5 kW | 3.05 N·m | Multi-turn absolute | Keyed | No | Verify exact unit | B320P family envelope |
These models share the same general B320P motor platform but differ in feedback, shaft configuration, and brake configuration. The resolver-based RJ and RK variants are explicitly listed as B320P resolver configurations, while the MJ variant uses multi-turn high-resolution feedback.
30. Same-Series Configuration Comparison
| Feature | MPL-B320P-RJ72AA | MPL-B320P-RJ74AA | MPL-B320P-RK72AA | MPL-B320P-RK74AA | MPL-B320P-MJ72AA |
|---|---|---|---|---|---|
| Motor Family | B320P | B320P | B320P | B320P | B320P |
| Frame | 100 mm | 100 mm | 100 mm | 100 mm | 100 mm |
| Stack | 50.8 mm | 50.8 mm | 50.8 mm | 50.8 mm | 50.8 mm |
| Speed | 5000 RPM | 5000 RPM | 5000 RPM | 5000 RPM | 5000 RPM |
| Power | 1.5 kW | 1.5 kW | 1.5 kW | 1.5 kW | 1.5 kW |
| Continuous Torque | 3.05 N·m | 3.05 N·m | 3.05 N·m | 3.05 N·m | 3.05 N·m |
| Peak Torque | 7.91 N·m | 7.91 N·m | 7.91 N·m | 7.91 N·m | 7.91 N·m |
| Feedback | Resolver | Resolver | Resolver | Resolver | Multi-turn absolute |
| Shaft | Keyed | Keyed | Keyless | Keyless | Keyed |
| Brake | No | 24 V DC | No | 24 V DC | No |
| Rotor Inertia | 0.000078 kg·m² | Approx. 0.000078 kg·m² | Approx. 0.000078 kg·m² | Approx. 0.000078 kg·m² | Approx. 0.000078 kg·m² |
| Weight | 3.85 kg | Verify exact unit | Verify exact unit | Verify exact unit | Verify exact unit |
| Dimensions | 42.799 × 21.692 × 26.01 cm | B320P family envelope | B320P family envelope | B320P family envelope | B320P family envelope |
31. Five Other Popular Allen-Bradley Servo Motor Models
The following models provide useful comparisons within the broader MPL servo motor family.
| Model | Voltage Class | Motor Class | Speed | Power | Continuous Torque | Feedback | Shaft | Brake | Approx. Weight | Dimensions |
|---|---|---|---|---|---|---|---|---|---|---|
| MPL-B310P-MJ74AA | 460 V | B310P | 5000 RPM | 0.77 kW | 1.58 N·m | Multi-turn absolute | Keyed | 24 V DC | 2.7 kg | B310P frame envelope |
| MPL-B320P-MK74AA | 460 V | B320P | 5000 RPM | 1.5 kW | 3.05 N·m | Multi-turn absolute | Keyless | 24 V DC | Approx. 4.5 kg | B320P envelope |
| MPL-B330P-MK74AA | 460 V | B330P | 5000 RPM | 1.8 kW | 4.18 N·m | Multi-turn absolute | Keyless | 24 V DC | Approx. 4.6 kg | B330P envelope |
| MPL-B420P-MJ74AA | 460 V | B420P | 5000 RPM | 1.9 kW | 4.74 N·m | Multi-turn absolute | Keyed | 24 V DC | Verify exact unit | B420P envelope |
| MPL-B430P-MJ72AA | 460 V | B430P | 5000 RPM | 2.2 kW | 6.55 N·m | Multi-turn absolute | Keyed | No | Verify exact unit | B430P envelope |
The B310P, B320P and B330P configurations are documented at approximately 0.77 kW, 1.5 kW and 1.8 kW respectively, all within the 5000 RPM class. The B320P provides 3.05 N·m continuous torque and 7.91 N·m peak torque.
For the alternative models, exact physical dimensions and weights can vary with configuration. The specific mechanical drawing should therefore be checked before using an alternative as a direct replacement.
32. B-Series Performance Comparison
| Model | Rated Speed | Power | Continuous Torque | Peak Torque | Rotor Inertia | Approx. Weight | Dimensions |
|---|---|---|---|---|---|---|---|
| MPL-B310P | 5000 RPM | 0.77 kW | 1.58 N·m | 3.61 N·m | 0.000044 kg·m² | 2.7 kg | B310P envelope |
| MPL-B320P | 5000 RPM | 1.5 kW | 3.05 N·m | 7.91 N·m | 0.000078 kg·m² | 3.7 kg family reference | B320P envelope |
| MPL-B330P | 5000 RPM | 1.8 kW | 4.18 N·m | 11.1 N·m | 0.00012 kg·m² | 4.6 kg | B330P envelope |
| MPL-B420P | 5000 RPM | 1.9 kW | 4.74 N·m | 13.5 N·m | 0.00026 kg·m² | Verify exact unit | B420P envelope |
| MPL-B430P | 5000 RPM | 2.2 kW | 6.55 N·m | 19.8 N·m | 0.00038 kg·m² | Verify exact unit | B430P envelope |
The B320P sits between the lower-output B310P and the higher-torque B330P/B420P/B430P configurations in this group.
33. RJ72AA vs. RJ74AA
The most direct alternative to the RJ72AA is the RJ74AA.
Both use resolver feedback and a keyed shaft.
The primary difference is the brake.
| Parameter | MPL-B320P-RJ72AA | MPL-B320P-RJ74AA |
|---|---|---|
| Power | 1.5 kW | 1.5 kW |
| Speed | 5000 RPM | 5000 RPM |
| Continuous Torque | 3.05 N·m | 3.05 N·m |
| Peak Torque | 7.91 N·m | 7.91 N·m |
| Feedback | Resolver | Resolver |
| Shaft | Keyed | Keyed |
| Brake | None | 24 V DC |
| Frame | 100 mm | 100 mm |
| Stack | 50.8 mm | 50.8 mm |
| Rotor Inertia | 0.000078 kg·m² | Approx. 0.000078 kg·m² |
| Weight | Approx. 3.85 kg | Verify exact unit |
| Dimensions | 42.799 × 21.692 × 26.01 cm | B320P family envelope |
For a horizontal machine axis where no holding brake is required, the RJ72AA configuration provides the no-brake arrangement.
For a vertical or gravity-loaded axis requiring an integrated holding brake, the RJ74AA configuration is the related alternative.
34. RJ72AA vs. RK72AA
The RJ72AA and RK72AA share resolver feedback and no-brake construction.
The main difference is the shaft.
| Parameter | MPL-B320P-RJ72AA | MPL-B320P-RK72AA |
|---|---|---|
| Power | 1.5 kW | 1.5 kW |
| Speed | 5000 RPM | 5000 RPM |
| Continuous Torque | 3.05 N·m | 3.05 N·m |
| Feedback | Resolver | Resolver |
| Shaft | Keyed | Keyless |
| Brake | None | None |
| Frame | 100 mm | 100 mm |
| Stack | 50.8 mm | 50.8 mm |
| Rotor Inertia | 0.000078 kg·m² | Approx. 0.000078 kg·m² |
| Weight | Approx. 3.85 kg | Verify exact unit |
| Dimensions | 42.799 × 21.692 × 26.01 cm | B320P family envelope |
The correct selection depends primarily on the mechanical coupling method used by the machine.
35. RJ72AA vs. MJ72AA
Both configurations use a keyed shaft and no brake.
Their main difference is feedback technology.
| Parameter | MPL-B320P-RJ72AA | MPL-B320P-MJ72AA |
|---|---|---|
| Power | 1.5 kW | 1.5 kW |
| Speed | 5000 RPM | 5000 RPM |
| Continuous Torque | 3.05 N·m | 3.05 N·m |
| Feedback | Resolver | Multi-turn absolute |
| Shaft | Keyed | Keyed |
| Brake | None | None |
| Frame | 100 mm | 100 mm |
| Stack | 50.8 mm | 50.8 mm |
| Rotor Inertia | 0.000078 kg·m² | Approx. 0.000078 kg·m² |
| Weight | Approx. 3.85 kg | Verify exact unit |
| Dimensions | 42.799 × 21.692 × 26.01 cm | B320P family envelope |
This distinction is important when replacing an existing motor because the servo drive must support the selected feedback system.
36. Practical Selection Guide
| Machine Requirement | Related Configuration |
|---|---|
| Resolver + keyed shaft + no brake | MPL-B320P-RJ72AA |
| Resolver + keyed shaft + 24 V DC brake | MPL-B320P-RJ74AA |
| Resolver + keyless shaft + no brake | MPL-B320P-RK72AA |
| Resolver + keyless shaft + 24 V DC brake | MPL-B320P-RK74AA |
| Multi-turn absolute + keyed shaft + no brake | MPL-B320P-MJ72AA |
| Multi-turn absolute + keyed shaft + brake | MPL-B320P-MJ74AA |
| Multi-turn absolute + keyless shaft + no brake | MPL-B320P-MK72AA |
| Multi-turn absolute + keyless shaft + brake | MPL-B320P-MK74AA |
37. Advantages for Machine Builders
The MPL-B320P-RJ72AA provides a straightforward combination of high-speed performance, low inertia, resolver feedback, keyed mechanical connection, and no integrated brake.
The keyed shaft is particularly convenient when the machine already uses keyed couplings.
The resolver configuration can also be useful when the existing servo architecture is designed around resolver feedback.
The no-brake configuration keeps the motor package relatively simple for applications where a holding brake is not required.
38. Advantages for Replacement Applications
The RJ72AA can be a practical replacement candidate when an existing machine uses the same basic configuration.
The following characteristics are especially important:
- 460 V-class operation
- 1.5 kW power
- 5000 RPM speed
- 3.05 N·m continuous torque
- Resolver feedback
- Keyed shaft
- No brake
- 100 mm frame
- 50.8 mm stack
- SpeedTEC DIN connector
- IEC metric mounting
A replacement should still be checked against the original motor’s exact series, revision, connector configuration, feedback interface, and mechanical dimensions.
39. Final Technical Specification Table
| Category | Specification |
|---|---|
| Model | MPL-B320P-RJ72AA |
| Brand | Allen-Bradley |
| Series | MP-Series MPL |
| Product Type | Low-Inertia Brushless AC Rotary Servo Motor |
| Voltage Class | 460 V AC |
| Product Rating | 480 V AC |
| Rated Power | 1.5 kW |
| Rated Speed | 5000 RPM |
| Maximum Speed | 5000 RPM |
| Continuous Torque | 3.05 N·m |
| Peak Torque | 7.91 N·m |
| Frame Size | 100 mm |
| Magnet Stack | 50.8 mm |
| Feedback | Resolver |
| Shaft | Keyed Shaft Extension |
| Shaft Seal | No Shaft Seal |
| Brake | No Integral Brake |
| Connector | SpeedTEC DIN |
| Connector Style | Right-Angle |
| Connector Rotation | 180° Rotatable |
| Mounting | IEC Metric Flange |
| Mounting Holes | Free, Type FF |
| Rotor Inertia | Approx. 0.000078 kg·m² |
| Duty | S1 |
| Operating Temperature Reference | 0–40 °C |
| Approx. Dimensions | 42.799 × 21.692 × 26.01 cm |
| Approx. Weight | 3.85 kg |
40. Final Product Overview
The Allen-Bradley MPL-B320P-RJ72AA is a 1.5 kW, 5000 RPM low-inertia brushless AC rotary servo motor designed for industrial motion-control applications.
Its 100 mm frame and 50.8 mm magnet stack provide a compact mechanical package while maintaining a useful combination of speed and torque.
The motor provides approximately 3.05 N·m continuous torque and 7.91 N·m peak torque, making it suitable for machine axes that require both sustained torque and short-duration acceleration torque.
The low rotor inertia of approximately 0.000078 kg·m² allows rapid changes in motor speed and makes the motor well suited to repetitive positioning, indexing, and high-cycle machine operation.
The resolver feedback is the defining feedback characteristic of the RJ72AA configuration. It provides the servo system with rotor-position information required for closed-loop operation.
The keyed shaft makes the motor suitable for conventional keyed mechanical connections and can be useful when integrating the motor with existing machine couplings, pulleys, gears, or other transmission components.
The motor has no integral brake, making it particularly appropriate for applications where the axis does not require a motor-mounted holding brake.
The SpeedTEC DIN right-angle connector and its approximately 180-degree rotation capability provide additional flexibility during installation and cable routing.
The MPL-B320P-RJ72AA therefore represents a practical combination of 5000 RPM high-speed performance, 1.5 kW output, low rotor inertia, resolver feedback, keyed shaft construction, compact 100 mm framing, and no-brake configuration.
For replacement work, the complete model number should be checked carefully. The RJ72AA should not be assumed to be interchangeable with visually similar B320P motors because resolver feedback, absolute feedback, keyed shafts, keyless shafts, and brake configurations can differ between models.