Introduction

The Allen Bradley MPL-B310P-RJ72AA Servo Motor is part of the MP-Series MPL family of low-inertia brushless servo motors. It is designed for industrial motion applications requiring controlled rotary movement, accurate feedback, and rapid response.

A defining feature of the RJ72AA is its resolver feedback configuration. Rather than using the high-resolution absolute or incremental feedback options found on other MPL variants, this model uses a 2-pole resolver. Resolver-based feedback remains useful in many industrial motion systems because of its robust construction and suitability for demanding electrical environments.

The motor has a 100 mm frame size and 25.4 mm magnet stack, while its rated speed reaches 5000 RPM. The combination provides a compact servo package for machinery where available installation space and dynamic response are both important.

The keyed shaft extension provides a familiar mechanical interface for industrial couplings and transmission components. The motor also uses a right-angle SpeedTEC DIN connector that can rotate 180 degrees, allowing installers to select a more convenient cable orientation.

Because the MPL-B310P-RJ72AA does not include an integral holding brake, it is particularly suitable for axes where the load does not require brake-assisted holding or where another mechanical holding arrangement is already incorporated into the machine.

For replacement applications, engineers should compare the existing motor's voltage, frame size, stack length, feedback type, shaft configuration, connector arrangement, and brake requirement rather than selecting a replacement based only on the model family.

Technical Specifications

Specification	MPL-B310P-RJ72AA
Brand	Allen Bradley / Rockwell Automation
Product Family	MP-Series MPL
Product Type	Low-Inertia AC Rotary Servo Motor
Catalog Number	MPL-B310P-RJ72AA
Motor Voltage	460 V AC
Voltage Class	400 V class
Rated Speed	5000 RPM
Rated Torque	1.58 N·m
Magnet Stack Length	25.4 mm (1.0 in.)
Frame Size	100 mm (3.94 in.)
Feedback	2-Pole Resolver
Shaft Configuration	Keyed Shaft Extension
Brake	No Brake
Connector	SpeedTEC DIN Connector
Connector Orientation	Right Angle
Connector Rotation	180° Rotatable
Mounting	IEC Metric, Free Mounting Holes, Type FF
Motor Type	Brushless Permanent-Magnet Servo Motor
Main Frame Dimension	100 mm
Magnet Stack Dimension	25.4 mm
Weight	2.70 kg (5.95 lb)

The exact operating performance of the motor depends on the selected servo drive, feedback interface, mechanical load, duty cycle, ambient conditions, and motion-control parameters.

Recommended Related Models

Model	Product Type	Configuration
MPL-B310P-RJ72AA	Servo Motor	Resolver, keyed shaft, no brake
MPL-B310P-RJ74AA	Servo Motor	Resolver, keyed shaft, 24 V DC brake
MPL-B310P-RK72AA	Servo Motor	Resolver, keyless shaft, no brake
MPL-B310P-RK74AA	Servo Motor	Resolver, keyless shaft, 24 V DC brake
MPL-B310P-HJ72AA	Servo Motor	Incremental feedback, keyed shaft, no brake
MPL-B310P-HJ74AA	Servo Motor	Incremental feedback, keyed shaft, brake
MPL-B310P-HK72AA	Servo Motor	Incremental feedback, keyless shaft, no brake

These models provide useful alternatives when the application requires a different shaft arrangement, feedback technology, or brake configuration.

Popular Related Models

Model	Product Family	Typical Configuration
MPL-B310P-MJ72AA	MP-Series MPL	Multi-turn absolute feedback, keyed shaft, no brake
MPL-B310P-MJ74AA	MP-Series MPL	Multi-turn absolute feedback, keyed shaft, brake
MPL-B310P-MK72AA	MP-Series MPL	Multi-turn absolute feedback, keyless shaft, no brake
MPL-B310P-MK74AA	MP-Series MPL	Multi-turn absolute feedback, keyless shaft, brake
MPL-B310P-HK72AA	MP-Series MPL	Incremental feedback, keyless shaft, no brake
MPL-B310P-HK74AA	MP-Series MPL	Incremental feedback, keyless shaft, brake
MPL-B310P-SK74AA	MP-Series MPL	Single-turn high-resolution feedback, keyless shaft, brake

When selecting an MPL replacement, feedback type is one of the most important parameters to verify. The MPL-B310P-RJ72AA is specifically configured for resolver feedback, so it should be matched with a compatible servo drive and motion architecture rather than substituted solely on the basis of its 100 mm frame size.

Applications

The MPL-B310P-RJ72AA is intended for automated machinery where reliable closed-loop rotary motion and predictable servo feedback are essential.

Packaging Machinery
The motor can be used for indexing, feeding, cutting, sealing, and other packaging movements. Its low-inertia construction supports responsive acceleration and deceleration during repetitive production cycles.

Material Handling Systems
Conveyors, transfer mechanisms, indexing tables, and automated positioning equipment can benefit from the motor's controlled servo operation.

Industrial Assembly Equipment
For assembly machines requiring repeatable rotary positioning, the resolver feedback configuration provides the control system with motor position information for closed-loop operation.

Printing and Converting Machinery
The MPL-B310P-RJ72AA can be applied to rollers, feeders, cutters, and other coordinated motion axes where speed regulation and positioning consistency are important.

Machine Tools and Automated Machinery
The 5000 RPM capability makes this motor suitable for various high-speed motion applications when the motor is correctly matched with the servo drive and mechanical load.

Existing Resolver-Based Motion Systems
One of the most important applications for this model is replacement or maintenance of equipment already designed around resolver feedback. Using the same feedback technology can simplify compatibility considerations during service work.

Advantages

Low-Inertia Servo Design
The MPL-B310P-RJ72AA belongs to the MPL low-inertia servo motor family. Low rotor inertia allows the motor to respond effectively to changing motion commands, making it useful for machines with frequent speed and position changes.

Resolver Feedback
The motor incorporates a 2-pole resolver rather than an incremental or absolute encoder. Resolver feedback can be advantageous in industrial environments where robust feedback performance and resistance to electrical interference are important considerations.

5000 RPM High-Speed Capability
A rated speed of up to 5000 RPM provides flexibility for high-cycle applications and rotary mechanisms requiring rapid motion.

Keyed Shaft Extension
The keyed shaft provides a conventional mechanical connection for compatible couplings, pulleys, gears, and other transmission components. Correct alignment and fastening remain essential during installation.

No Integrated Brake
The RJ72AA configuration does not include a holding brake. This makes it appropriate for applications where an integrated motor brake is unnecessary or where the machine uses another mechanical holding method.

Rotatable Right-Angle Connector
The SpeedTEC DIN connector is arranged at a right angle and can be rotated 180 degrees. This gives machine builders more flexibility when routing power and feedback cables.

IEC Metric Mounting
The 100 mm metric frame and free mounting-hole configuration make the motor suitable for a variety of industrial machine structures.

Technical FAQs

1. What type of feedback does the MPL-B310P-RJ72AA use?
The MPL-B310P-RJ72AA uses a 2-pole resolver for motor feedback. The connected motion controller and servo drive must support the appropriate resolver feedback interface.

2. What is the rated motor speed?
The motor is specified for operation up to 5000 RPM. Actual operating speed depends on the drive configuration, load, acceleration profile, and application conditions.

3. Does the MPL-B310P-RJ72AA include a holding brake?
No. The RJ72AA configuration is a no-brake version. If an application requires mechanical holding when servo power is removed, an external braking or load-holding solution may need to be considered.

4. What shaft configuration does this model use?
The motor has a keyed shaft extension. The mating coupling or transmission component should be selected for the appropriate shaft dimensions and installed with proper alignment.

5. What voltage is the MPL-B310P-RJ72AA designed for?
The motor is specified for a 460 V armature voltage and belongs to the 400 V class of MPL servo motors. The motor must be matched with an appropriate Allen-Bradley servo drive.

6. Can this motor replace an MPL motor with encoder feedback?
Not automatically. Although motors may have similar frame sizes and mechanical characteristics, the feedback technology is different. The servo drive and motion controller must support the resolver interface before using the RJ72AA as a replacement.

7. What should be checked when a resolver feedback fault occurs?
Inspect the feedback cable, connector seating, resolver wiring, shielding, grounding, and drive configuration. Also check for damaged cables, loose terminals, excessive electrical noise, or incorrect feedback parameters.

8. How should the motor be commissioned after installation?
Verify the motor catalog data and resolver configuration in the servo drive first. Then check mechanical alignment, cable connections, motor direction, feedback response, acceleration limits, and operating current. Initial testing should be performed at low speed before full automatic operation.

9. What causes excessive servo motor vibration?
Possible causes include mechanical misalignment, an unsuitable coupling, excessive load inertia, incorrect servo tuning, damaged bearings, incorrect feedback configuration, or mechanical resonance. Servo diagnostics and mechanical inspection should be used together to identify the actual cause.

10. What maintenance should be performed on the MPL-B310P-RJ72AA?
Regularly inspect the motor mounting bolts, shaft coupling, feedback connector, power connections, and cables. Monitor abnormal noise, vibration, temperature, and changes in servo performance. Resolver and power cables should also be protected from mechanical damage and excessive electromagnetic interference.

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