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MPL-B420P-HJ72AA Low-Inertia Servo Motor

1. Product Overview

The MPL-B420P-HJ72AA is a 400 V class, three-phase, low-inertia brushless servo motor designed for high-speed industrial motion-control applications.

It belongs to the MP-Series MPL Low-Inertia Servo Motor family and uses a 115 mm frame with a 50.8 mm magnet stack. The motor is rated for 5000 RPM, provides approximately 4.74 N·m of continuous torque, and has a 13.5 N·m peak torque capability. It uses a 2000-line incremental encoder, a keyed shaft, a SpeedTec DIN connector, and has no integrated brake in this particular configuration.

The HJ72AA configuration is intended for applications where fast acceleration, high rotational speed, repeatable positioning, and compact servo-motor construction are important.

The motor uses a low-inertia permanent-magnet rotor design. The relatively low rotor inertia allows the servo system to accelerate and decelerate the motor rapidly, which is particularly useful in machines with frequent starts, stops, indexing movements, and rapid position changes.

The model is also closely associated with Kinetix and other compatible servo-drive systems used in industrial automation. The published technical data identifies compatibility with several drive families, including Kinetix 5500, Kinetix 6200/6500, Kinetix 6000, Kinetix 300, Kinetix 350, Kinetix 2000, Kinetix 7000, and Ultra 3000.

The exact model MPL-B420P-HJ72AA has been discontinued, with an engineering replacement identified as MPL-B420P-SJ72AA. This is important when the motor is being purchased for maintenance or replacement purposes because the HJ72AA may now be encountered primarily as existing equipment, replacement stock, refurbished equipment, or surplus inventory.

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2. Brand and Product Classification

Parameter	Specification
Brand	Allen-Bradley
Product Family	MP-Series
Product Series	MPL Low-Inertia Servo Motors
Product Type	Rotary Servo Motor
Model	MPL-B420P-HJ72AA
Motor Technology	Brushless Permanent-Magnet Servo Motor
Application	Industrial Motion Control
Motor Frame	Frame 4
Frame Size	115 mm
Magnet Stack	50.8 mm / 2.0 in.
Voltage Class	400 V AC
Nominal Armature Voltage	460 V
Phase	Three Phase
Rated Speed	5000 RPM
Maximum Speed	5000 RPM
Continuous Torque	4.74 N·m
Peak Torque	13.5 N·m
Continuous Power	1.9 kW
Feedback	2000-line Incremental Encoder
Feedback Resolution	2000 pulses/revolution
Shaft	Keyed Shaft
Shaft Seal	No Shaft Seal
Brake	No Brake
Connector	SpeedTec DIN Connector
Connector Orientation	Right-angle, rotatable
Mounting	IEC Metric Flange Mount
Rotor Inertia	Approximately 0.00026 kg·m²
Operating Temperature	Approximately 0 to 40 °C
Approximate Weight	4.56 kg
Dimensions	115 mm frame; 50.8 mm magnet stack; complete envelope configuration-dependent
Product Status	Discontinued
Engineering Replacement	MPL-B420P-SJ72AA

The exact HJ72AA specifications identify a 115 mm frame, 50.8 mm stack, 5000 RPM speed, incremental encoder, keyed shaft, no brake, and SpeedTec DIN connector.

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3. Detailed Technical Specifications

Technical Parameter	MPL-B420P-HJ72AA
Model	MPL-B420P-HJ72AA
Product Series	MPL Low Inertia
Motor Type	Rotary Servo Motor
Motor Construction	Brushless Permanent-Magnet
Voltage Class	400 V AC
Armature Voltage	460 V
Electrical Phase	3 Phase
Rated Speed	5000 RPM
Maximum Speed	5000 RPM
Continuous Torque	4.74 N·m
Peak Torque	13.5 N·m
Rated Continuous Power	1.9 kW
Rotor Inertia	0.00026 kg·m²
Feedback Type	Incremental Encoder
Encoder Resolution	2000 pulses/rev
Brake	No Brake
Shaft	Keyed
Shaft Seal	No Shaft Seal
Connector	SpeedTec DIN
Connector Type	Circular DIN
Connector Position	Right Angle
Connector Rotation	Approximately 180° rotatable
Mounting	IEC Metric Flange
Frame Size	115 mm
Magnet Stack Length	50.8 mm
Approximate Weight	4.56 kg
Dimensions	115 mm frame class × 50.8 mm magnetic stack; complete mechanical envelope depends on exact mounting/shaft configuration
Operating Temperature	0 to 40 °C
Intended Drive System	Compatible servo amplifier / motion controller
Typical Application	High-speed industrial motion control

The published technical specification gives 4.74 N·m continuous torque, 13.5 N·m peak torque, 1.9 kW continuous power, 0.00026 kg·m² rotor inertia, and 5000 RPM rated and maximum speed.

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4. Dimensions and Weight

The MPL-B420P-HJ72AA uses a Frame 4 / 115 mm motor body and a 20 / 50.8 mm magnet stack.

The 115 mm frame dimension is an important mechanical selection parameter because it determines the general mounting size of the motor. The 50.8 mm stack length identifies the active magnetic stack used by this particular B420P configuration.

The complete external envelope should not be treated as simply 115 × 50.8 mm. A servo motor also includes the front flange, shaft extension, connector assembly, rear cover, and mounting features.

Therefore, for machine replacement work, the exact mechanical drawing should be checked before machining a mounting plate or coupling interface.

Mechanical Parameter	Specification
Model	MPL-B420P-HJ72AA
Frame Size	115 mm
Frame Designation	Frame 4
Frame Width Class	115 mm
Magnet Stack Length	50.8 mm
Magnet Stack	2.0 in.
Mounting Style	IEC Metric Flange
Shaft	Keyed
Shaft Seal	None
Connector	SpeedTec DIN
Connector Position	Right-angle
Connector Rotation	180° rotatable
Overall Installed Dimensions	Configuration-dependent
Approximate Weight	4.56 kg
Weight in Pounds	Approximately 10.06 lb

The exact model is listed at approximately 10.01–10.06 lb depending on the product listing, equivalent to roughly 4.54–4.56 kg. For catalog purposes, approximately 4.56 kg is a practical specification.

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5. Product Series

The MPL-B420P-HJ72AA belongs to the MPL Low-Inertia Servo Motor series.

The MPL series is designed around brushless permanent-magnet servo motor technology. The B420P configuration is one of the larger standard motor sizes in the B-series and provides a combination of high rotational speed, moderate continuous torque, and relatively low rotor inertia.

The MPL family includes multiple frame sizes, stack lengths, feedback options, shaft arrangements, brake options, and connector configurations.

The HJ72AA is one specific configuration rather than a generic B420P motor. Its designation identifies the combination of voltage class, feedback arrangement, shaft configuration, connector arrangement, and other mechanical/electrical characteristics.

For this reason, replacing an HJ72AA motor with another B420P model should not be done solely because both models carry the B420P designation. Feedback type, brake configuration, shaft arrangement, connector type, and drive compatibility also need to be checked.

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6. Meaning of the HJ72AA Configuration

The MPL-B420P-HJ72AA model designation identifies a particular combination within the MPL product family.

The MPL portion identifies the low-inertia servo motor family.

The B420P identifies the motor size and performance class.

The H portion belongs to the specific H-series configuration family.

The J portion is associated with the incremental feedback/keyed-shaft configuration represented by this model.

The 72AA portion identifies the specific voltage, connector, revision, and configuration combination.

The complete model number should therefore be treated as the purchasing and replacement reference.

A motor with the same basic B420P designation but a different suffix can have a different feedback system, shaft arrangement, brake configuration, or connector configuration.

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7. Motor Performance

7.1 5000 RPM High-Speed Operation

The MPL-B420P-HJ72AA is rated for 5000 RPM.

This relatively high rotational speed makes the motor suitable for machinery where rapid indexing, high-speed positioning, and fast cyclic operation are required.

High-speed servo motors are particularly useful in machines where the axis needs to complete repeated movements within short cycle times.

Applications can include:

• Packaging machines
• Printing machinery
• Semiconductor equipment
• Automated assembly
• Material handling
• Machine tools
• Converting equipment
• Inspection machinery
• High-speed indexing systems

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8. Continuous Torque

The motor provides approximately 4.74 N·m continuous torque.

Continuous torque is the torque that the motor can produce during continuous operating conditions within its specified thermal and electrical limits.

This makes the B420P suitable for applications requiring sustained controlled torque rather than only short acceleration peaks.

The actual usable torque in a machine depends on:

• Motor speed
• Ambient temperature
• Duty cycle
• Drive configuration
• Acceleration profile
• Load inertia
• Mechanical transmission
• Cooling conditions
• Machine operating cycle

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9. Peak Torque

The published peak torque specification is approximately 13.5 N·m.

Peak torque is important during acceleration, deceleration, rapid direction changes, and other short-duration high-load events.

The difference between continuous torque and peak torque allows the servo motor to handle short periods of substantially higher torque than its continuous operating level.

For machine sizing, the continuous load and peak load should be evaluated separately.

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10. 1.9 kW Continuous Power

The MPL-B420P-HJ72AA is specified at approximately 1.9 kW continuous output power.

This places the motor in a useful range for medium-power industrial servo applications.

The combination of approximately 1.9 kW power, 4.74 N·m continuous torque, and 5000 RPM speed provides a useful balance between motor size and dynamic performance.

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11. Low-Inertia Design

Low rotor inertia is one of the defining characteristics of the MPL series.

The HJ72AA has a listed rotor inertia of approximately:

0.00026 kg·m²

Low inertia is particularly beneficial when the machine requires rapid acceleration and deceleration.

For example, an indexing machine may repeatedly move from zero speed to high speed and then stop at a precise position.

A lower-inertia motor can make this type of operation easier for the servo system because the drive does not have to accelerate and decelerate as much rotating mass.

This can contribute to:

• Faster response
• Shorter cycle times
• Faster indexing
• Reduced acceleration time
• Better dynamic response
• More responsive position control

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12. Incremental Encoder

The HJ72AA uses a 2000-line incremental encoder.

The encoder provides rotational position information to the servo system.

The feedback system allows the controller to monitor motor movement and regulate:

• Position
• Speed
• Acceleration
• Deceleration
• Direction
• Motion synchronization

The 2000-line feedback configuration is different from the absolute multi-turn feedback used by some other MPL models.

Therefore, the feedback type is one of the most important items to verify when selecting a replacement.

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13. Keyed Shaft

The MPL-B420P-HJ72AA uses a keyed shaft.

A keyed shaft provides a mechanical interface for compatible couplings, pulleys, gears, or other transmission components.

The keyway helps transmit torque between the motor shaft and the attached mechanical component.

When replacing an existing motor, the shaft diameter, key dimensions, shaft extension, coupling type, and mounting position should all be checked.

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14. No Integrated Brake

The HJ72AA configuration is specified as No Brake.

This means the motor does not contain the integrated 24 V holding brake found on some other MPL configurations.

This can be appropriate for horizontal rotary axes or applications where an external mechanical holding mechanism is not required.

For vertical axes, however, the absence of an integrated brake needs to be considered carefully.

If the machine requires the load to remain mechanically held after motor power is removed, an external braking or load-holding solution may be necessary.

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15. SpeedTec DIN Connector

The motor uses a SpeedTec DIN connector.

The connector arrangement is designed for industrial servo-motor wiring and provides a relatively compact connection method for motor power and feedback-related connections.

The HJ72AA configuration is specified with a right-angle connector arrangement and approximately 180° rotational flexibility.

This can be useful when the motor is installed in machinery with restricted cable-routing space.

Proper cable routing is important because motor power cables and feedback cables can be susceptible to electrical noise when installed incorrectly.

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16. Applications

16.1 Industrial Automation

The MPL-B420P-HJ72AA can be used in automated production equipment requiring accurate rotary motion.

Typical functions include:

• Indexing
• Positioning
• Synchronized rotation
• Conveyor control
• Product transfer
• Assembly movement
• Machine-axis control

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16.2 Packaging Machinery

Packaging machinery often requires fast and repetitive servo movement.

The 5000 RPM motor speed and low-inertia construction make this type of servo motor suitable for high-cycle machinery.

Potential applications include:

• Film handling
• Cutting mechanisms
• Product positioning
• Labeling
• Sealing
• Indexing
• Packaging transfer

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16.3 Printing and Converting Machinery

Printing and converting equipment often requires coordinated motion between several rotating axes.

Servo motors can provide controlled speed and synchronization between mechanical sections.

Potential uses include:

• Web handling
• Roll positioning
• Cutter control
• Feed rollers
• Registration systems
• Tension-related motion

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16.4 Machine Tools

Servo motors can be used in machine-tool auxiliary axes and other controlled rotary mechanisms.

The B420P’s 5000 RPM operating speed can be useful where rapid positioning is required.

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16.5 Automated Assembly

Assembly equipment frequently uses servo motors for:

• Rotary positioning
• Component insertion
• Indexing tables
• Rotary fixtures
• Screwdriving mechanisms
• Component transfer
• Precision alignment

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16.6 Material Handling

The motor can be used in automated material-handling machinery where controlled rotary motion is converted into linear or rotary movement through a mechanical transmission.

Examples include:

• Conveyor drives
• Rollers
• Rotary transfer units
• Pick-and-place mechanisms
• Positioning systems

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16.7 Inspection Equipment

Inspection systems can require precise positioning of cameras, sensors, fixtures, or workpieces.

Servo motors can provide controlled movement and repeatable positioning.

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17. Product Advantages

17.1 High-Speed 5000 RPM Operation

The 5000 RPM rating allows the motor to support high-speed machine cycles.

This is useful when the machine must complete multiple motion cycles within a short period.

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17.2 Low Rotor Inertia

The low-inertia design supports rapid acceleration and deceleration.

This is particularly valuable in machines with frequent starts and stops.

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17.3 4.74 N·m Continuous Torque

The continuous torque rating provides useful output for medium-duty industrial motion applications.

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17.4 13.5 N·m Peak Torque

The higher peak torque capability helps the motor handle short-duration acceleration and load changes.

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17.5 1.9 kW Power

The approximately 1.9 kW power rating provides a useful balance between motor output and physical size.

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17.6 2000-Line Incremental Feedback

The incremental encoder provides feedback suitable for conventional servo motion-control applications.

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17.7 Keyed Shaft

The keyed shaft provides a familiar mechanical interface for couplings and other rotary transmission components.

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17.8 Rotatable DIN Connector

The right-angle, rotatable connector arrangement can simplify installation in machines where cable clearance is limited.

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17.9 IEC Metric Flange

The metric flange mounting arrangement makes the motor suitable for many industrial machine constructions using metric mechanical standards.

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18. Five Related or Same-Series Models

The following models are closely related to the B420P-HJ72AA and can be considered when comparing feedback type, shaft configuration, brake configuration, and motor performance.

Model	Series / Type	Speed	Continuous Torque	Peak Torque	Power	Feedback	Shaft	Brake	Frame / Stack	Approx. Weight
MPL-B420P-MJ72AA	MPL B420P Rotary Servo	5000 RPM	4.74 N·m	13.5 N·m	1.9 kW	Multi-turn high-resolution	Keyed	No	115 mm / 50.8 mm	Configuration-dependent
MPL-B420P-MK72AA	MPL B420P Rotary Servo	5000 RPM	4.74 N·m	13.5 N·m	1.9 kW	Multi-turn high-resolution	Keyless	No	115 mm / 50.8 mm	Configuration-dependent
MPL-B420P-SJ72AA	MPL B420P Rotary Servo	5000 RPM	4.74 N·m	13.5 N·m	1.9 kW	Single-turn high-resolution	Keyed	No	115 mm / 50.8 mm	Configuration-dependent
MPL-B420P-SK72AA	MPL B420P Rotary Servo	5000 RPM	4.74 N·m	13.5 N·m	1.9 kW	Single-turn high-resolution	Keyless	No	115 mm / 50.8 mm	Configuration-dependent
MPL-B430P-SJ72AA	MPL B430P Rotary Servo	5000 RPM	6.55 N·m	19.8 N·m	2.2 kW	Single-turn high-resolution	Keyed	No	Larger B430 frame	Approx. 5.5 kg*

The B420P family uses the same basic 115 mm frame and 50.8 mm stack across several feedback and shaft configurations, while the B430P provides a higher torque and power class.

*The 5.5 kg value is representative of the B430P family specification and should not be treated as the exact weight of every B430P suffix.

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19. B420P Configuration Comparison

Model	Feedback	Shaft	Brake	Speed	Continuous Torque	Peak Torque	Power
MPL-B420P-HJ72AA	Incremental Encoder	Keyed	No	5000 RPM	4.74 N·m	13.5 N·m	1.9 kW
MPL-B420P-MJ72AA	Multi-turn High Resolution	Keyed	No	5000 RPM	4.74 N·m	13.5 N·m	1.9 kW
MPL-B420P-MK72AA	Multi-turn High Resolution	Keyless	No	5000 RPM	4.74 N·m	13.5 N·m	1.9 kW
MPL-B420P-SJ72AA	Single-turn High Resolution	Keyed	No	5000 RPM	4.74 N·m	13.5 N·m	1.9 kW
MPL-B420P-SK72AA	Single-turn High Resolution	Keyless	No	5000 RPM	4.74 N·m	13.5 N·m	1.9 kW

The main difference among these B420P configurations is not simply the motor’s power rating. Feedback type and shaft configuration can significantly affect compatibility with the drive and machine mechanics.

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20. Five Representative Same-Brand Models

The following five models represent useful comparison points within the same general servo-motor portfolio.

Model	Motor Series	Speed	Continuous Torque	Peak Torque	Power	Frame / Stack	Feedback Example	Approx. Weight	Dimensions
MPL-B310P	MPL Low Inertia	5000 RPM	1.58 N·m	3.61 N·m	0.77 kW	100 mm class	Configuration-dependent	Approx. 2.7 kg	Approx. 100 mm frame; exact envelope configuration-dependent
MPL-B320P	MPL Low Inertia	5000 RPM	3.05 N·m	7.91 N·m	1.5 kW	100 mm class	Configuration-dependent	Approx. 3.7 kg	Approx. 100 mm frame; exact envelope configuration-dependent
MPL-B330P	MPL Low Inertia	5000 RPM	4.18 N·m	11.1 N·m	1.8 kW	100 mm / 76.2 mm stack class	Configuration-dependent	Approx. 4.6 kg	Approx. 100 mm frame; exact envelope configuration-dependent
MPL-B420P	MPL Low Inertia	5000 RPM	4.74 N·m	13.5 N·m	1.9 kW	115 mm / 50.8 mm	Configuration-dependent	Approx. 4.3 kg family value	115 mm frame; exact envelope configuration-dependent
MPL-B430P	MPL Low Inertia	5000 RPM	6.55 N·m	19.8 N·m	2.2 kW	Larger B430 frame	Configuration-dependent	Approx. 5.5 kg	Larger frame; exact envelope configuration-dependent

The published MPL technical data gives the performance figures shown for the B310P through B430P motor families.

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21. Same-Brand Model Performance Comparison

Model	Rated Speed	Continuous Torque	Peak Torque	Power	Rotor Inertia	Approx. Weight
MPL-B310P	5000 RPM	1.58 N·m	3.61 N·m	0.77 kW	0.000044 kg·m²	2.7 kg
MPL-B320P	5000 RPM	3.05 N·m	7.91 N·m	1.5 kW	0.000078 kg·m²	3.7 kg
MPL-B330P	5000 RPM	4.18 N·m	11.1 N·m	1.8 kW	0.00012 kg·m²	4.6 kg
MPL-B420P	5000 RPM	4.74 N·m	13.5 N·m	1.9 kW	0.00026 kg·m²	4.3 kg family value
MPL-B430P	5000 RPM	6.55 N·m	19.8 N·m	2.2 kW	0.00038 kg·m²	5.5 kg

These values show the progression from the smaller B310P through the higher-output B430P. The exact weight of a particular suffix can differ from the family-level value because feedback, brake, shaft, and other configuration choices can affect the finished motor.

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22. Recommended Model Selection by Application

Application Requirement	Suitable Model Group	Reason
Lower power and compact servo motion	MPL-B310P	Lower torque and power requirement
Medium-power high-speed motion	MPL-B320P	1.5 kW and 3.05 N·m continuous torque
Higher torque within smaller frame class	MPL-B330P	4.18 N·m continuous torque
B420P replacement with incremental feedback	MPL-B420P-HJ72AA	2000-line incremental encoder and keyed shaft
B420P with multi-turn feedback	MPL-B420P-MJ72AA	Multi-turn high-resolution feedback
B420P with single-turn feedback	MPL-B420P-SJ72AA	Single-turn high-resolution feedback
Higher torque and power	MPL-B430P	6.55 N·m continuous torque and 2.2 kW
Keyless shaft requirement	MPL-B420P-MK72AA / SK72AA	Keyless mechanical configuration

The selection should always be based on the complete model number rather than only the motor family name.

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23. Advantages for Machine Builders

Mechanical Integration

The 115 mm frame provides a defined motor mounting class that can be incorporated into industrial machine structures.

The IEC metric flange mounting arrangement is useful for equipment designed around standardized metric mechanical dimensions.

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Electrical Integration

The 460 V three-phase configuration is suitable for industrial servo systems designed around the corresponding voltage class.

The SpeedTec DIN connector also provides a standardized connection approach within the motor family.

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Motion Performance

The combination of 5000 RPM speed, 4.74 N·m continuous torque, 13.5 N·m peak torque, and low rotor inertia provides a strong combination for fast cyclic motion.

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Feedback Capability

The 2000-line incremental encoder gives the servo drive feedback needed for closed-loop motion control.

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Mechanical Coupling

The keyed shaft provides a conventional torque-transmission interface.

This can simplify replacement where the existing machine already uses a compatible keyed coupling.

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24. Maintenance and Replacement Considerations

When replacing an MPL-B420P-HJ72AA, the complete model number should be checked carefully.

A replacement motor should match the following characteristics wherever required:

• Motor frame
• Stack length
• Voltage class
• Feedback type
• Encoder resolution
• Shaft type
• Shaft dimensions
• Brake configuration
• Connector type
• Connector orientation
• Mounting flange
• Motor power
• Continuous torque
• Peak torque
• Drive compatibility

A motor that has the same B420P designation but a different feedback or shaft suffix should not automatically be considered a direct replacement.

The HJ72AA specifically uses an incremental encoder and keyed shaft, while other B420P configurations use multi-turn, single-turn, or resolver feedback and may use keyless shafts.

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25. Drive Compatibility

The published technical information identifies the HJ72AA as compatible with several servo-drive families.

Drive Family	Compatibility Information
Kinetix 5500	Compatible drive family
Kinetix 6200 / 6500	Compatible drive family
Kinetix 6000	Compatible drive family
Kinetix 300	Compatible drive family
Kinetix 350	Compatible drive family
Kinetix 2000	Compatible drive family
Kinetix 7000	Compatible drive family
Ultra 3000	Compatible drive family

Drive compatibility should be confirmed using the exact drive catalog number, motor feedback configuration, cable configuration, and required motor parameters before commissioning.

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26. Operating Environment

The technical data specifies an operating range of approximately 0 to 40 °C for the motor configuration.

The motor should be installed in an environment where the housing can dissipate heat effectively.

When the motor is operated continuously at high load or high speed, the machine designer should consider:

• Ambient temperature
• Motor mounting
• Heat transfer
• Duty cycle
• Load profile
• Cabinet temperature
• Cable routing
• Vibration
• Shock
• Contamination

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27. Typical Industrial Equipment

The MPL-B420P-HJ72AA can be found in or considered for equipment such as:

Equipment Type	Typical Servo Function
Packaging Machine	High-speed indexing
Labeling Machine	Roller and feed control
Printing Machine	Web and roller synchronization
Assembly Machine	Rotary positioning
Automated Conveyor	Controlled rotary movement
Inspection Machine	Positioning and indexing
Machine Tool	Auxiliary axis movement
Material Handling System	Transfer and positioning
Converting Equipment	Feed and cutting
Automated Fixture	Rotary positioning
Production Line	Synchronized motion
Pick-and-Place Equipment	Rotary axis movement

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28. Important Difference Between HJ72AA and Other B420P Models

The B420P model name alone does not identify the complete electrical configuration.

For example, the HJ72AA uses an incremental encoder, while the MJ72AA and MK72AA configurations are associated with multi-turn high-resolution feedback.

The SJ72AA and SK72AA configurations are associated with single-turn high-resolution feedback.

The HJ72AA and MJ72AA use keyed-shaft configurations, while the MK72AA and SK72AA configurations use keyless-shaft arrangements.

This means the suffix can be just as important as the basic B420P designation when replacing a motor.

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29. Product Advantages Summary

Feature	MPL-B420P-HJ72AA Benefit
5000 RPM Speed	Suitable for high-cycle motion
4.74 N·m Continuous Torque	Supports medium-duty continuous loads
13.5 N·m Peak Torque	Handles short acceleration/load peaks
1.9 kW Power	Suitable for medium-power servo applications
Low Rotor Inertia	Supports rapid acceleration and deceleration
2000-Line Encoder	Closed-loop motion feedback
Keyed Shaft	Conventional mechanical torque transmission
No Brake	Appropriate for applications not requiring an integrated holding brake
115 mm Frame	Defined industrial mounting class
50.8 mm Stack	Standard B420P magnetic stack
SpeedTec DIN Connector	Flexible industrial cable connection
460 V Operation	Suitable for corresponding high-voltage servo systems
IEC Metric Mounting	Convenient for metric machine construction

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30. Technical Specification Summary

Item	Specification
Brand	Allen-Bradley
Product Family	MP-Series
Product Series	MPL Low-Inertia Servo Motors
Model	MPL-B420P-HJ72AA
Product Type	Rotary Servo Motor
Motor Technology	Brushless Permanent-Magnet Servo
Voltage Class	400 V AC
Armature Voltage	460 V
Phase	Three Phase
Rated Speed	5000 RPM
Maximum Speed	5000 RPM
Continuous Torque	4.74 N·m
Peak Torque	13.5 N·m
Continuous Power	1.9 kW
Rotor Inertia	0.00026 kg·m²
Feedback	2000-Line Incremental Encoder
Encoder Resolution	2000 pulses/rev
Shaft	Keyed
Shaft Seal	No Shaft Seal
Brake	No Brake
Connector	SpeedTec DIN
Connector Style	Right Angle
Connector Rotation	180°
Mounting	IEC Metric Flange
Frame	Frame 4
Frame Size	115 mm
Magnet Stack	50.8 mm / 2.0 in.
Dimensions	115 mm frame class; 50.8 mm stack; full envelope configuration-dependent
Weight	Approximately 4.56 kg
Operating Temperature	Approximately 0–40 °C
Typical Application	Industrial Servo Motion
Product Status	Discontinued
Engineering Replacement	MPL-B420P-SJ72AA

The core specifications above are based on the exact HJ72AA configuration, including its 5000 RPM speed, 4.74 N·m continuous torque, 13.5 N·m peak torque, 1.9 kW continuous power, 115 mm frame, 50.8 mm stack, incremental encoder, keyed shaft, and no brake.

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31. Final Product Description

The MPL-B420P-HJ72AA is a high-speed, low-inertia rotary servo motor designed for industrial motion-control systems requiring accurate closed-loop operation, rapid acceleration, and reliable continuous torque.

With a 5000 RPM rated speed, 4.74 N·m continuous torque, 13.5 N·m peak torque, and approximately 1.9 kW continuous power, it provides a balanced combination of speed and torque for medium-power automation equipment.

Its 115 mm frame, 50.8 mm magnet stack, keyed shaft, 2000-line incremental encoder, and SpeedTec DIN connector define a specific mechanical and electrical configuration within the MPL B420P family.

The low-inertia construction is particularly useful for machines that perform frequent acceleration and deceleration. The motor can therefore be applied to high-speed indexing, packaging, assembly, material handling, printing, converting, and other automated production equipment.

The absence of an integrated brake makes the HJ72AA different from brake-equipped servo configurations. For applications where the motor must mechanically hold a vertical or gravity-loaded axis after power removal, the machine design must provide an appropriate external holding solution or use a compatible brake-equipped motor configuration.

For replacement applications, the complete MPL-B420P-HJ72AA catalog number should be matched carefully. The HJ72AA is not interchangeable with every B420P motor because other suffixes can change the feedback system, shaft design, brake configuration, or other electrical and mechanical characteristics.

The model is also a discontinued configuration, so users maintaining older machinery should pay particular attention to exact replacement compatibility and the designated engineering replacement when planning future maintenance.

In practical terms, the MPL-B420P-HJ72AA is best understood as a 115 mm-frame, 5000 RPM, 1.9 kW-class, low-inertia industrial servo motor with 4.74 N·m continuous torque, 13.5 N·m peak torque, 2000-line incremental feedback, a keyed shaft, and no integrated brake.