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MPL-B540K-SK72AA Low-Inertia Servo Motor – Complete Product Guide

1. Product Overview

The MPL-B540K-SK72AA is a 4000 rpm low-inertia rotary servo motor in the MPL series. It is designed for demanding industrial motion-control applications where high rotational speed, strong torque output, accurate positioning, and fast dynamic response are required.

This model uses a 460 V electrical configuration, a 165 mm frame size, and a 101.6 mm magnet stack. It combines a 5.4 kW continuous power rating with approximately 19.4 N·m of continuous torque and 48.6 N·m of peak torque.

One of the most important characteristics of the SK72AA configuration is its keyless shaft. Unlike keyed versions of the same motor family, the shaft is designed without a traditional shaft key, which can be useful in applications using specially designed couplings, clamping hubs, or other precision mechanical connection systems.

The motor also uses a single-turn high-resolution absolute encoder. This provides accurate feedback for servo control and allows the drive to determine rotor position within one mechanical revolution without relying on a conventional incremental-only feedback arrangement.

The motor is supplied without an integral holding brake. This makes the SK72AA particularly suitable for horizontal axes and applications where a motor brake is not required.

The connector is a SpeedTEC DIN right-angle type with a 180-degree rotatable arrangement. This helps simplify cable routing when the motor is installed in a confined machine structure.

2. Brand

Brand: Allen-Bradley

The MPL-B540K-SK72AA belongs to the Allen-Bradley motion-control product family and is part of the MP-Series servo motor range.

For industrial users, the model is normally identified by the complete catalog number because the individual suffix characters describe important mechanical and feedback options. The difference between keyed and keyless shafts, for example, can be critical when replacing an existing servo motor.

3. Product Series

Series: MP-Series MPL Low-Inertia Servo Motors

Product Type: Brushless rotary servo motor

Motor Family: MPL Low-Inertia

The MPL series is designed around a low-inertia servo motor concept. The objective is to provide a motor that can accelerate and decelerate rapidly while maintaining strong torque performance.

The MPL-B540K-SK72AA belongs to the larger 165 mm frame group and uses a 101.6 mm magnetic stack. This places it above smaller MPL motors in terms of torque and power capability while maintaining the 4000 rpm operating class.

The MPL family includes different combinations of speed, feedback, shaft design, brake configuration, connector arrangement, frame size, and magnet-stack length. This makes the series suitable for a broad range of automated machinery.

4. Complete Model Identification

The catalog number can be interpreted as a configuration rather than simply a model name.

Model Code Element	Configuration
MPL-B540K-SK72AA	Complete catalog number
MPL	Low-inertia servo motor family
B	460 V class configuration
5	Frame size 165 mm
40	101.6 mm magnet stack
K	4000 rpm speed class
S	Single-turn high-resolution encoder
K	Keyless shaft
7	SpeedTEC DIN right-angle connector
2	No integral brake
AA	Standard configuration suffix

The manufacturer’s product selection data specifically identifies this model as a 460 V, frame-size-5, 101.6 mm stack, 4000 rpm motor with a single-turn high-resolution encoder, keyless shaft, SpeedTEC DIN right-angle connector, and no brake.

5. Main Technical Parameters

Parameter	MPL-B540K-SK72AA
Model	MPL-B540K-SK72AA
Product Type	Rotary servo motor
Product Series	MPL Low Inertia
Motor Family	MP-Series servo motor
Voltage Class	400 V AC class
Armature Voltage	460 V
Rated Speed	4000 rpm
Maximum Speed	4000 rpm
Rated Power	5.4 kW continuous
Continuous Torque	19.4 N·m
Peak Torque	48.6 N·m
Frame Size	165 mm
Magnet Stack	101.6 mm
Feedback	Single-turn high-resolution absolute encoder
Feedback Resolution	Sin/Cos, 1024 cycles/rev
Feedback Protocol	Hiperface
Shaft	Keyless
Brake	No integral brake
Connector	SpeedTEC DIN, right-angle
Connector Rotation	180° rotatable
Mounting	Metric flange mount
Mounting Holes	Free mounting holes, Type FF
Shaft Seal	No
Rotor Inertia	Approx. 0.00157 kg·m²
Maximum Operating Temperature	40 °C
Approx. Basic Motor Weight	About 15 kg class
Overall Dimensions	Exact L × W × H should be taken from the mechanical drawing
Frame Diameter / Size Reference	165 mm
Magnet Stack Length	101.6 mm

The core performance figures are approximately 5.4 kW, 19.4 N·m continuous torque, 48.6 N·m peak torque, and 4000 rpm. The detailed configuration data also specifies the 165 mm frame, 101.6 mm stack, single-turn feedback, keyless shaft, and no brake.

6. Dimensions

The MPL-B540K-SK72AA uses a Frame 5 / 165 mm frame and a 40 / 101.6 mm magnet stack.

Dimension Parameter	Value
Model	MPL-B540K-SK72AA
Frame Size	165 mm
Magnet Stack Length	101.6 mm
Frame Reference	Frame 5
Stack Reference	40
Mounting Standard	IEC metric
Mounting Hole Type	Free mounting holes, Type FF
Shaft Type	Keyless
Connector Orientation	Right-angle
Connector Rotation	180°
Overall Motor Length	Refer to mechanical drawing
Overall Motor Width	Refer to mechanical drawing
Overall Motor Height	Refer to mechanical drawing

It is important not to confuse the 165 mm frame size with the total outside length of the motor. The 165 mm figure identifies the frame-size class, while the 101.6 mm value refers to the magnet stack. The complete mechanical envelope also depends on the front flange, shaft arrangement, connector configuration, and other physical features.

For machine design work, the official mechanical drawing should therefore be used for exact mounting-hole positions, shaft geometry, flange dimensions, connector clearance, and overall envelope dimensions. The product page confirms that mechanical drawing data is available for this model.

7. Weight

The motor belongs to the approximately 15 kg class for the B540K configuration.

Weight Parameter	Value
Model	MPL-B540K-SK72AA
Approximate Motor Weight	About 15 kg
Weight Including Packaging	Not specified
Weight Including Cables	Not specified
Brake Weight	Not applicable
Shaft Type	Keyless

The basic B540K family is listed around the 15 kg range, with a comparable no-brake B540K configuration listed at approximately 15.42 kg. Actual shipping weight can be higher because packaging, connectors, protective materials, and accessories are not necessarily included in the motor net-weight figure.

8. Power Rating

The continuous rated power of the MPL-B540K family is approximately 5.4 kW.

This power rating makes the motor suitable for machinery requiring substantially more output than smaller 3 kW-class servo motors.

A 5.4 kW servo motor is particularly useful where the machine requires both relatively high speed and substantial torque. The 4000 rpm rating is especially valuable in applications where a combination of speed and torque is more important than simply maximizing low-speed torque.

Power Parameter	Specification
Model	MPL-B540K-SK72AA
Continuous Rated Power	5.4 kW
Rated Speed	4000 rpm
Continuous Torque	19.4 N·m
Peak Torque	48.6 N·m
Voltage Class	400 V AC
Armature Voltage	460 V

The published MPL technical data identifies the B540K as a 5.4 kW, 4000 rpm motor with 19.4 N·m continuous torque and 48.6 N·m peak torque.

9. Speed Performance

The rated speed of the MPL-B540K-SK72AA is 4000 rpm, and its maximum listed speed is also 4000 rpm.

This makes it a high-speed servo motor compared with many 2000 rpm and 3000 rpm motors used in industrial machinery.

The 4000 rpm rating is useful for:

• High-speed indexing.
• Fast rotary positioning.
• High-throughput packaging.
• Web handling.
• Converting machinery.
• High-speed material movement.
• Ball-screw-driven linear axes.
• High-cycle automated assembly.

The high-speed configuration allows the motor to complete a greater number of motion cycles in a given period when the machine mechanics and drive system are properly matched.

10. Torque Performance

The B540K motor provides approximately 19.4 N·m continuous torque and 48.6 N·m peak torque.

Torque Parameter	Value
Model	MPL-B540K-SK72AA
Continuous Torque	19.4 N·m
Peak Torque	48.6 N·m
Continuous / Peak Ratio	Approx. 2.5:1
Rated Speed	4000 rpm
Rated Power	5.4 kW

The peak torque capability is important during acceleration, deceleration, indexing, and short-duration load disturbances.

In a properly sized servo system, the motor can use its peak torque capability for dynamic motion while operating within its continuous torque rating during sustained operation.

11. Rotor Inertia

The rotor inertia is approximately 0.00157 kg·m² for the detailed B540K configuration data.

Low rotor inertia is an important characteristic of servo motors because the motor does not need to overcome as much rotational inertia during acceleration and deceleration.

This can provide benefits in applications involving:

• Rapid indexing.
• Frequent start-stop motion.
• Repeated acceleration and deceleration.
• Short positioning cycles.
• High-speed electronic camming.
• High-speed registration.

The low-inertia design is one of the main reasons the MPL series is useful for dynamic motion-control systems.

12. Feedback System

The MPL-B540K-SK72AA uses a single-turn high-resolution absolute encoder.

The detailed configuration specifies Sin/Cos feedback with 1024 cycles per revolution and Hiperface protocol.

Feedback Parameter	Specification
Model	MPL-B540K-SK72AA
Feedback Type	Absolute single-turn
Encoder Type	High-resolution encoder
Resolution	Sin/Cos, 1024 cycles/rev
Feedback Protocol	Hiperface
Position Information	Single mechanical revolution
Application Benefit	Accurate servo position feedback

The feedback system is particularly important in applications where accurate velocity regulation, position control, synchronization, and repeatability are required.

The absolute single-turn arrangement also makes this configuration different from a multi-turn encoder configuration. When selecting a replacement motor, the feedback type must therefore be matched to the existing control architecture.

13. Keyless Shaft Configuration

One of the defining features of the SK72AA is the keyless shaft.

A keyless shaft does not use the traditional mechanical key and keyway arrangement found on keyed servo motors.

This can be advantageous when the machine uses:

• Precision clamping couplings.
• Special shaft hubs.
• Shrink-disc or clamping systems.
• High-precision mechanical couplings.
• Applications where shaft balance and concentricity are important.
• Custom mechanical transmission components.

The keyless design can also simplify certain coupling arrangements because the coupling is secured through the appropriate clamping mechanism rather than relying on a conventional shaft key.

However, the shaft interface must always be checked before replacing a keyed motor with a keyless motor. A motor with the same electrical rating is not automatically a mechanical replacement.

14. No Integral Brake

The MPL-B540K-SK72AA is supplied without an integral motor brake.

This is represented by the “2” brake configuration in the model code.

Brake Parameter	Specification
Model	MPL-B540K-SK72AA
Integral Brake	No
Brake Voltage	Not applicable
Brake Type	No motor-mounted holding brake
Typical Advantage	Lower mechanical complexity
Typical Application	Horizontal axes and non-brake-dependent motion

The absence of a brake can be an advantage when the application does not require mechanical holding torque.

For vertical axes, however, the absence of an integral brake must be considered carefully. A vertical load can move under gravity when motor torque is removed, so an external safety or holding mechanism may be necessary depending on the machine design.

15. Connector Configuration

The motor uses a SpeedTEC DIN right-angle connector.

The connector can be rotated through 180 degrees, giving the machine designer additional flexibility for cable routing.

This is useful when the motor is mounted inside a compact machine where a straight connector could interfere with surrounding components.

Connector Parameter	Specification
Model	MPL-B540K-SK72AA
Connector Type	SpeedTEC DIN
Connector Style	Right-angle
Rotation	180° rotatable
Connection Type	Quick-connect arrangement
Application Benefit	Flexible cable routing

The connector arrangement is part of the original model configuration and should be considered when ordering replacement motors or cables.

16. Mounting Configuration

The MPL-B540K-SK72AA uses a metric flange mounting arrangement.

The product configuration specifies free mounting holes, Type FF.

This mounting style is suitable for industrial machine structures where the motor is installed directly against a machined mounting surface.

The mounting interface should be checked for:

• Flange diameter.
• Bolt-hole pattern.
• Shaft centerline.
• Shaft projection.
• Mounting depth.
• Connector clearance.
• Coupling clearance.
• Cable bend radius.

Even when another motor has the same frame size and power rating, differences in shaft and flange dimensions can prevent direct mechanical substitution.

17. Main Product Advantages

High-Speed 4000 rpm Operation

The 4000 rpm rating makes the motor suitable for high-cycle industrial motion.

This is especially valuable when machine productivity depends on rapid positioning and short motion cycles.

Strong Continuous Torque

With approximately 19.4 N·m of continuous torque, the motor can handle demanding continuous motion loads.

The torque level places it in a significantly stronger class than smaller B520K motors.

High Peak Torque

The approximately 48.6 N·m peak torque capability gives the motor substantial short-duration acceleration capacity.

This is useful for machines that repeatedly accelerate heavy mechanical loads.

Low-Inertia Rotor

The low-inertia rotor design supports rapid acceleration and deceleration.

This is one of the major characteristics of the MPL product family.

Absolute Single-Turn Feedback

The high-resolution single-turn feedback system provides precise position information for servo control.

This is useful for applications requiring accurate positioning and repeatable motion.

Keyless Shaft

The keyless shaft is useful for precision coupling systems and machines designed around clamping-style mechanical transmission components.

Flexible Connector Orientation

The 180-degree rotatable right-angle connector provides greater freedom when routing motor cables.

Compact Industrial Servo Package

The 165 mm frame and 101.6 mm stack provide a substantial power level without moving into the very large frame sizes used by higher-torque servo motors.

18. Typical Applications

Packaging Machinery

The MPL-B540K-SK72AA can be used in packaging machinery where high-speed servo motion is required.

Typical functions include:

• Product positioning.
• Film handling.
• Rotary indexing.
• Conveyor synchronization.
• Cutting mechanisms.
• Sealing mechanisms.
• Label positioning.
• High-speed indexing.

Material Handling

Material-handling systems often require fast acceleration and precise stopping.

The B540K combination of 4000 rpm speed and 19.4 N·m continuous torque makes it suitable for demanding material-handling axes.

Ball-Screw Linear Axes

When coupled to an appropriate ball screw, the motor can convert rotary motion into precise linear movement.

Applications may include:

• Pick-and-place machines.
• Automated inspection systems.
• Machine positioning.
• Linear transfer systems.
• Assembly equipment.

The final linear speed and force depend on the screw lead, mechanical efficiency, gearbox arrangement, and servo operating point.

Automated Assembly

Automated assembly machines frequently require rapid movement followed by accurate positioning.

The low-inertia motor design is particularly useful for repeated acceleration and deceleration cycles.

Electronic Assembly Equipment

Electronic manufacturing machinery often needs precise, repeatable motion with short cycle times.

The single-turn high-resolution feedback system can support these motion requirements when properly integrated with the servo drive and control system.

Printing and Converting

High-speed rotary motion is common in printing, web handling, slitting, winding, and converting machinery.

The 4000 rpm operating class is beneficial in applications where the motor must maintain high rotational speed while providing controlled acceleration.

Machine Tools

The motor can also be considered for machine-tool auxiliary axes and other motion systems where high-speed servo control and precise positioning are required.

The exact suitability depends on the machine load, duty cycle, acceleration requirements, feedback architecture, and mechanical transmission.

19. Five Same-Series or Closely Related Models

The following models are useful for comparison because they remain within the same MPL family or closely related B540K configuration.

Model	Speed	Continuous Torque	Peak Torque	Power	Feedback	Shaft	Brake	Frame / Stack	Approx. Weight
MPL-B540K-SJ72AA	4000 rpm	19.4 N·m	48.6 N·m	5.4 kW	Single-turn absolute	Keyed	No	165 / 101.6 mm	Approx. 15 kg
MPL-B540K-SK72AA	4000 rpm	19.4 N·m	48.6 N·m	5.4 kW	Single-turn absolute	Keyless	No	165 / 101.6 mm	Approx. 15 kg
MPL-B540K-SK74AA	4000 rpm	19.4 N·m	48.6 N·m	5.4 kW	Single-turn absolute	Keyless	24 V DC	165 / 101.6 mm	Approx. 19 kg
MPL-B540K-MJ74AA	4000 rpm	19.4 N·m	48.6 N·m	5.4 kW	Multi-turn absolute	Keyed	24 V DC	165 / 101.6 mm	Approx. 19 kg
MPL-B540K-MK74AA	4000 rpm	19.4 N·m	48.6 N·m	5.4 kW	Multi-turn absolute	Keyless	24 V DC	165 / 101.6 mm	Approx. 19 kg

The important point in this table is that the basic motor performance can remain very similar while the shaft, feedback, and brake configuration changes.

The SK72AA is therefore not simply a generic B540K motor. Its exact combination of single-turn feedback, keyless shaft, no brake, and SpeedTEC DIN connector needs to be matched when selecting a replacement.

20. Comparison With the Keyed B540K Configuration

The keyed version is mechanically different from the SK72AA.

Feature	MPL-B540K-SK72AA	MPL-B540K-SJ72AA
Speed	4000 rpm	4000 rpm
Continuous Torque	19.4 N·m	19.4 N·m
Peak Torque	48.6 N·m	48.6 N·m
Power	5.4 kW	5.4 kW
Feedback	Single-turn	Single-turn
Shaft	Keyless	Keyed
Brake	No	No
Frame	165 mm	165 mm
Magnet Stack	101.6 mm	101.6 mm
Weight	Approx. 15 kg	Approx. 15 kg

The primary difference is the shaft configuration.

For a machine using a clamping-type coupling, the SK72AA may be the more appropriate configuration.

For a machine designed around a conventional keyed coupling, the SJ72AA may be the better match.

21. Comparison With the Brake Version

The SK74AA has the same general B540K performance class but adds an integral 24 V DC brake.

Feature	MPL-B540K-SK72AA	MPL-B540K-SK74AA
Speed	4000 rpm	4000 rpm
Power	5.4 kW	5.4 kW
Continuous Torque	19.4 N·m	19.4 N·m
Peak Torque	48.6 N·m	48.6 N·m
Feedback	Single-turn	Single-turn
Shaft	Keyless	Keyless
Brake	No	24 V DC
Frame	165 mm	165 mm
Magnet Stack	101.6 mm	101.6 mm
Weight	Approx. 15 kg	Approx. 19 kg

The SK74AA can therefore be more suitable when a holding brake is required, while the SK72AA is simpler when no integral brake is necessary. The SK74AA configuration is documented as a 5.4 kW, 4000 rpm, single-turn, keyless motor with a 24 V brake.

22. Five Popular Models From the Same Brand

The following MPL models provide useful reference points for comparing different power and torque levels.

Model	Rated Speed	Power	Continuous Torque	Peak Torque	Rotor Inertia	Frame / Stack	Approx. Weight
MPL-B520K	4000 rpm	3.5 kW	10.7 N·m	23.2 N·m	0.000783 kg·m²	165 mm / 50.8 mm	9.8 kg
MPL-B540D	2000 rpm	3.4 kW	19.4 N·m	41.0 N·m	0.00147 kg·m²	165 mm / 101.6 mm	15 kg
MPL-B540K	4000 rpm	5.4 kW	19.4 N·m	48.6 N·m	Approx. 0.00147 kg·m²	165 mm / 101.6 mm	Approx. 15 kg
MPL-B560F	3000 rpm	5.5 kW	26.8 N·m	67.8 N·m	0.00213 kg·m²	165 mm / longer stack	20.2 kg
MPL-B580F	3000 rpm	7.1 kW	34.0 N·m	87.0 N·m	0.00289 kg·m²	165 mm / longer stack	25.4 kg

The published MPL product profile gives the B520K, B540D, B540K, and B560F performance figures, including speed, power, inertia, continuous torque, and peak torque.

The comparison shows that the B540K is positioned between the smaller B520K and the larger B560F/B580F models.

23. MPL-B520K Compared With MPL-B540K

The B520K is a smaller-output option.

The B520K provides approximately 3.5 kW and 10.7 N·m continuous torque, while the B540K provides approximately 5.4 kW and 19.4 N·m.

Parameter	MPL-B520K	MPL-B540K
Speed	4000 rpm	4000 rpm
Power	3.5 kW	5.4 kW
Continuous Torque	10.7 N·m	19.4 N·m
Peak Torque	23.2 N·m	48.6 N·m
Rotor Inertia	0.000783 kg·m²	Approx. 0.00147 kg·m²
Weight	9.8 kg	Approx. 15 kg

The B520K is attractive when lower motor mass and lower torque capacity are sufficient.

The B540K is preferable when the machine needs considerably more torque and power while retaining 4000 rpm operation.

24. MPL-B540D Compared With MPL-B540K

Both motors have approximately 19.4 N·m continuous torque, but they emphasize different operating characteristics.

Parameter	MPL-B540D	MPL-B540K
Speed	2000 rpm	4000 rpm
Power	3.4 kW	5.4 kW
Continuous Torque	19.4 N·m	19.4 N·m
Peak Torque	41.0 N·m	48.6 N·m
Rotor Inertia	0.00147 kg·m²	Approx. 0.00147 kg·m²
Weight	15 kg	Approx. 15 kg

The B540D is oriented toward lower-speed, higher-torque-demand applications.

The B540K is the better choice when high rotational speed is important.

25. MPL-B560F Compared With MPL-B540K

The B560F increases continuous and peak torque while reducing rated speed to 3000 rpm.

Parameter	MPL-B540K	MPL-B560F
Speed	4000 rpm	3000 rpm
Power	5.4 kW	5.5 kW
Continuous Torque	19.4 N·m	26.8 N·m
Peak Torque	48.6 N·m	67.8 N·m
Rotor Inertia	Approx. 0.00147 kg·m²	0.00213 kg·m²
Weight	Approx. 15 kg	20.2 kg

This is a useful example of how motor selection should be based on the actual machine motion profile rather than power alone.

If high speed is the priority, the B540K is attractive.

If greater torque is needed at a lower operating speed, the B560F can be more appropriate.

26. MPL-B580F Compared With MPL-B540K

The B580F is another step upward in torque capacity.

Parameter	MPL-B540K	MPL-B580F
Speed	4000 rpm	3000 rpm
Power	5.4 kW	7.1 kW
Continuous Torque	19.4 N·m	34.0 N·m
Peak Torque	48.6 N·m	87.0 N·m
Rotor Inertia	Approx. 0.00147 kg·m²	0.00289 kg·m²
Weight	Approx. 15 kg	25.4 kg

The B580F is better suited to heavier loads and applications requiring greater torque capacity.

The B540K remains attractive when high speed, moderate motor mass, and dynamic response are more important.

27. Servo Drive Compatibility

The B540K family is designed for use with compatible servo drive systems in the corresponding motion-control platform.

Published technical data identifies compatibility across several drive families, including Kinetix 5500, Kinetix 6200/6500, Kinetix 6000, Kinetix 300, Kinetix 350, Kinetix 2000, Kinetix 7000, and Ultra 3000 configurations.

Drive Family	Application Relationship
Kinetix 5500	Servo motion applications
Kinetix 6200 / 6500	Modular motion systems
Kinetix 6000	Integrated motion platform
Kinetix 300	Compact servo applications
Kinetix 350	Compact machine motion
Kinetix 2000	Multi-axis servo systems
Kinetix 7000	High-power motion applications
Ultra 3000	Servo drive applications

The exact drive selection must be based on motor current, voltage, feedback compatibility, control architecture, and application requirements.

28. Mechanical Installation Considerations

The motor should be installed on a rigid and properly machined mounting surface.

A flexible mounting structure can introduce vibration and reduce positioning accuracy.

The coupling should be correctly aligned with the motor shaft. Misalignment can result in excessive bearing loads, vibration, noise, and shortened motor life.

Because the SK72AA uses a keyless shaft, the coupling must be compatible with the specified shaft interface.

Before installation, check:

• Motor frame size.
• Flange dimensions.
• Shaft diameter.
• Shaft extension.
• Coupling type.
• Connector clearance.
• Cable routing.
• Motor orientation.
• Mounting-bolt specification.
• Load inertia.
• Required acceleration.
• Continuous and peak torque requirements.

29. Cable Routing

The right-angle SpeedTEC DIN connector is helpful in compact machine installations.

However, cable routing should still provide enough clearance for the connector and the minimum cable-bending requirements.

The cable should not be forced sharply against the motor connector.

Avoid:

• Excessive bending.
• Continuous mechanical tension.
• Cable rubbing.
• Excessive vibration at the connector.
• Contact with hot machine surfaces.
• Contact with moving mechanical components.

Good cable routing is especially important on machines with repeated axis movement.

30. Vertical-Axis Considerations

The SK72AA does not include an integral brake.

This makes the model more naturally suited to horizontal axes.

For vertical applications, the designer must consider what happens when the servo drive is disabled or power is removed.

A vertical load can move because of gravity if there is no mechanical holding system.

Depending on the machine safety concept, an external brake, counterbalance, mechanical locking system, or other suitable load-retention method may be necessary.

The absence of a motor brake should therefore be treated as a deliberate selection characteristic rather than a minor specification.

31. Maintenance Considerations

Servo motors generally require less routine maintenance than many mechanical transmission components, but the motor and surrounding system should still be inspected regularly.

Recommended inspection areas include:

• Motor mounting bolts.
• Coupling condition.
• Shaft alignment.
• Connector condition.
• Cable condition.
• Unusual vibration.
• Abnormal acoustic noise.
• Excessive motor temperature.
• Encoder feedback behavior.
• Drive fault history.
• Mechanical load changes.

A change in vibration or operating temperature can sometimes indicate a mechanical problem rather than an electrical motor problem.

32. Replacement Selection Checklist

When replacing an existing motor with an MPL-B540K-SK72AA, the following items should be checked.

Selection Item	Required Match
Model	MPL-B540K-SK72AA
Voltage	460 V configuration
Speed	4000 rpm
Power	5.4 kW
Continuous Torque	19.4 N·m
Peak Torque	48.6 N·m
Frame	165 mm
Stack	101.6 mm
Feedback	Single-turn high-resolution
Shaft	Keyless
Brake	No brake
Connector	SpeedTEC DIN right-angle
Mounting	Metric flange
Mounting Holes	Type FF
Shaft Seal	No
Weight	Approximately 15 kg class

Matching only the motor power is not enough.

The feedback type, shaft arrangement, brake configuration, connector, mechanical envelope, and drive compatibility should all be verified before replacement.

33. Why the Keyless Shaft Matters

The keyless shaft is one of the most important characteristics of this exact catalog number.

Two motors can have identical power, speed, torque, frame size, and feedback type but still be mechanically incompatible because one uses a keyed shaft and the other uses a keyless shaft.

For this reason, the “K” shaft designation should not be ignored when purchasing a replacement.

A machine originally designed around a clamping coupling may benefit from the SK72AA configuration.

A machine originally designed around a keyed coupling may require a keyed variant instead.

34. Why the No-Brake Configuration Matters

The absence of a brake affects machine behavior when the servo is disabled.

For horizontal axes, this can be perfectly acceptable.

For vertical axes or mechanisms where the motor must hold position after power removal, a brake or external mechanical holding mechanism may be necessary.

The no-brake configuration can also reduce the mechanical complexity of the motor itself and avoid unnecessary brake wiring when a holding brake is not required.

35. Why the 4000 rpm Rating Matters

The 4000 rpm rating is one of the strongest reasons to select the B540K configuration.

Compared with 2000 rpm versions, a 4000 rpm motor can provide much higher rotational speed.

This can reduce the required transmission ratio in certain machine designs.

It can also help increase machine throughput where the mechanical system can safely operate at the corresponding speed.

However, high-speed operation requires appropriate attention to coupling balance, load inertia, bearings, lubrication of connected mechanical components, and the overall mechanical design.

36. Application Selection Guide

Application	Suitability
High-speed indexing	Excellent
Packaging equipment	Excellent
Material handling	Very suitable
Ball-screw axis	Very suitable
Automated assembly	Excellent
Electronic assembly	Excellent
Printing/converting	Very suitable
Horizontal rotary axis	Excellent
High-speed positioning	Excellent
Vertical axis without external brake	Not recommended
Keyed-shaft coupling system	Not directly suitable
Keyless clamping coupling system	Very suitable

This table is a practical selection guide rather than a substitute for detailed servo sizing.

37. Overall Advantages

The main advantages of the MPL-B540K-SK72AA can be summarized as follows.

High rotational speed: 4000 rpm operation makes it suitable for high-cycle machinery.

Strong torque capacity: 19.4 N·m continuous torque and 48.6 N·m peak torque provide substantial motion capability.

5.4 kW output: The motor occupies a useful middle-to-high industrial servo power range.

Low-inertia design: Supports rapid acceleration and deceleration.

Absolute feedback: Single-turn high-resolution feedback supports precise servo control.

Keyless shaft: Suitable for clamping-type and precision coupling systems.

No unnecessary brake: Appropriate for applications that do not require a motor-mounted holding brake.

Flexible connector: The right-angle connector can be rotated 180 degrees for easier machine integration.

165 mm frame: Provides a substantial torque level without requiring one of the largest MPL frame sizes.

Industrial versatility: Suitable for packaging, assembly, material handling, converting, positioning, and other automated machinery.

38. Important Selection Notes

The MPL-B540K-SK72AA should not be selected solely because its power rating appears suitable.

Servo motor sizing should consider:

• Continuous load torque.
• Peak load torque.
• Average torque.
• Acceleration torque.
• Deceleration torque.
• Load inertia.
• Reflected inertia.
• Required speed.
• Duty cycle.
• Mechanical transmission ratio.
• Coupling type.
• Vertical or horizontal installation.
• Environmental conditions.
• Encoder requirements.
• Brake requirements.
• Drive compatibility.

A motor that is oversized may increase cost and inertia without providing a practical advantage, while an undersized motor may overheat or repeatedly enter current or torque limits.

39. Complete Technical Summary

Technical Category	MPL-B540K-SK72AA
Model	MPL-B540K-SK72AA
Brand	Allen-Bradley
Product Family	MP-Series
Product Series	MPL Low Inertia
Motor Type	Brushless rotary servo motor
Voltage	460 V armature
Voltage Class	400 V AC
Rated Speed	4000 rpm
Maximum Speed	4000 rpm
Rated Power	5.4 kW
Continuous Torque	19.4 N·m
Peak Torque	48.6 N·m
Frame Size	165 mm
Magnet Stack	101.6 mm
Feedback	Single-turn high-resolution absolute encoder
Feedback Resolution	Sin/Cos, 1024 cycles/rev
Feedback Protocol	Hiperface
Shaft	Keyless
Brake	None
Connector	SpeedTEC DIN
Connector Position	Right-angle
Connector Rotation	180°
Mounting	Metric flange
Mounting Holes	Type FF
Shaft Seal	No
Rotor Inertia	Approx. 0.00157 kg·m²
Maximum Operating Temperature	40 °C
Approximate Weight	About 15 kg
Overall Dimensions	Use mechanical drawing for exact L × W × H
Main Application	Industrial servo motion control

The primary model data is consistent with the product configuration information for the exact SK72AA catalog number.

40. Final Product Assessment

The MPL-B540K-SK72AA is a strong choice for industrial servo applications requiring a combination of high speed, substantial torque, accurate feedback, and a keyless mechanical interface.

Its 4000 rpm speed and 5.4 kW power rating give it a useful balance between productivity and mechanical performance.

The approximately 19.4 N·m continuous torque rating makes it capable of handling demanding continuous loads, while the approximately 48.6 N·m peak torque rating provides additional capacity for acceleration and short-duration load changes.

The single-turn high-resolution absolute encoder makes the motor suitable for precision motion systems, while the keyless shaft makes it particularly interesting for machines using clamping-style couplings or specially engineered mechanical interfaces.

The lack of an integral brake should be regarded as an intentional configuration advantage for applications that do not require motor-mounted holding torque. For vertical axes, however, an appropriate external holding solution may be necessary.

The 165 mm frame and 101.6 mm magnet stack place this motor in a substantial industrial servo class without moving into the very largest MPL motor configurations.

Overall, the MPL-B540K-SK72AA is best viewed as a high-speed, 5.4 kW, low-inertia industrial servo motor intended for precision automated machinery, especially applications where 4000 rpm operation, strong dynamic performance, single-turn absolute feedback, and a keyless shaft are important.

For an exact replacement, the most important items to match are the complete catalog number, feedback type, shaft configuration, brake configuration, connector arrangement, frame size, magnet stack, and mechanical mounting dimensions rather than power rating alone.