Allen Bradley 460v 4.5a 1.5kw MPL-B320P-SJ72AA Kinetix Servo Motor

Allen-Bradley MPL-B320P-SJ72AA | Kinetix MP-Series Low-Inertia Brushless Servo Motor — 1.5kW, 3.05Nm, 5000RPM, 460V, 100mm Frame, SpeedTEC DIN, Single-Turn Encoder

Part Number: MPL-B320P-SJ72AA

Bulletin: MPL — Low-Inertia Brushless Servo Motors

Voltage Class: 460V (B Series)

Rated Output: 1.5 kW

Continuous Stall Torque: 3.05 Nm (2.7 lb·in)

Peak Stall Torque: 7.91 Nm (7.0 lb·in)

Continuous Stall Current: 4.5 A

Peak Stall Current: 14.0 A

Rated Speed: 5,000 RPM

Rotor Inertia: 0.000078 kg·m² (0.00069 lb·in·s²)

Frame Size: 3 — 100 mm (3.94 in.)

Magnet Stack Length: 50.8 mm (2.0 in.)

Encoder: Single-Turn High-Resolution

Connector: SpeedTEC DIN, Right-Angle, 180° Rotatable

Shaft: Keyed Extension, No Brake, No Shaft Seal

IP Rating: IP53 (shaft down) / IP51 (horizontal) / IP50 (shaft up) — IP66 with shaft seal

Insulation Class: H (356°F / 180°C)

Weight: Approx. 5.805 kg

Compatible Drives: Kinetix 5500, 5700, 6200/6500, 6000, 300/350, 2000, 7000

Condition: New / Surplus

Overview

The Allen-Bradley MPL-B320P-SJ72AA is a Kinetix MP-Series low-inertia brushless AC servo motor in the 460V class, delivering 1.5 kW continuous output with 3.05 Nm stall torque and a 5,000 RPM speed rating. Built on a 100 mm frame with a 50.8 mm magnet stack, it produces a 7.91 Nm peak torque — a 2.6:1 peak-to-continuous ratio — through a rare-earth permanent magnet rotor that keeps inertia exceptionally low at 0.000078 kg·m².

That combination sits at the practical core of what high-throughput automation demands: enough torque to handle the load, fast enough rotor response to change velocity quickly, in a physical package compact enough to fit the machine's motor cavity without extensive redesign.

The SJ72AA connector suffix identifies the SpeedTEC DIN circular connector in the right-angle, 180° rotatable configuration.

The 180° rotation capability is not a minor convenience — on machines where the motor mounting position puts the cable exit pointing toward a fixed structure, being able to rotate the connector head without disturbing the connector wiring solves the cable routing problem at the motor rather than at the machine design level. 

The SpeedTEC locking collar provides positive, vibration-resistant engagement with a single-turn action that is faster and more reliably fully seated than multi-turn connector threads.

The single-turn high-resolution encoder provides absolute position data within each revolution.

Without a battery or capacitor backup, the encoder confirms shaft position immediately at power-up within the current turn — the drive reads the correct angular position from the first scan cycle, without requiring a homing move within the single revolution.

For the full multi-turn absolute position that eliminates homing across the entire axis travel, the multi-turn encoder variant (MJ suffix in the part number series) is the alternative specification.

Key Specifications

Low Inertia at 100 mm — What the Rotor Design Delivers

The 0.000078 kg·m² rotor inertia is the specification that shapes how the MPL-B320P-SJ72AA behaves in a motion system.

A lighter rotor changes velocity faster for a given torque impulse — the angular acceleration is torque divided by total inertia, and the total inertia is the sum of rotor inertia plus the load inertia reflected to the motor shaft.

When the rotor inertia is as low as this motor achieves, the drive's ability to accelerate and decelerate the load quickly is limited primarily by the peak torque (7.91 Nm) and the load inertia, not by the rotor mass.

In positioning applications — the pick-and-place, indexing, and assembly moves that define factory automation cycle times — the move time between positions depends directly on how fast the motor can accelerate to peak velocity and decelerate to stop. Faster acceleration and deceleration produce shorter move times per cycle.

If a machine makes 200 positioning moves per minute across a ten-hour shift, reducing each move time by 10ms produces 120 additional seconds of available production capacity per shift. The low-inertia design makes each of those accelerations as sharp as the peak current allows.

The rare-earth permanent magnets in the MPL rotor generate the magnetic flux that the stator windings react against to produce torque.

Rare-earth magnet materials provide higher flux density than conventional ferrite magnets in the same physical volume — which is how the MPL series achieves 3.05 Nm continuous stall torque in a 100 mm, 50.8 mm stack motor that weighs under 6 kg.

3.05 Nm Continuous, 7.91 Nm Peak — Sizing the Axis

The continuous stall torque of 3.05 Nm is the thermal limit: the motor can sustain this torque continuously without the winding temperature exceeding the Class H insulation limit of 180°C, provided the mounting surface conducts heat away from the motor housing adequately and the ambient temperature stays within the 0–40°C operating range.

The peak stall torque of 7.91 Nm is available for the duration that the Kinetix drive's thermal model and current limits permit.

At 14.0A peak versus 4.5A continuous, the I²R heating during peak current is approximately 9.7 times the continuous rate — peak torque is available for brief bursts during acceleration phases, not for extended operation.

The drive monitors motor thermal state through the winding temperature model and limits peak current duration accordingly.

For axis sizing, the RMS torque calculation across the full move cycle determines whether the MPL-B320P-SJ72AA is correctly specified: the RMS torque — accounting for acceleration torque, running torque, and deceleration torque weighted by their respective time durations — must be below 3.05 Nm for the motor to operate within its thermal limits continuously.

If the RMS torque calculation comes out above 3.05 Nm, the next stack length up in the MPL B3 series (MPL-B330P) with its higher continuous torque rating is the correct selection.

5,000 RPM and the 460V Platform

The 5,000 RPM rated speed puts the MPL-B320P-SJ72AA at the high end of the speed range for 100 mm frame servo motors. On a 10mm lead ball screw with 1:1 coupling, 5,000 RPM delivers 50 m/min rapid traverse — well above the 20–30 m/min typical of many medium-duty machine axes.

This speed headroom is particularly valuable in systems where the axis spends most of its duty cycle at moderate speeds under load, but requires brief rapid traverse moves at maximum velocity between operations.

The B (460V) voltage class is the European and global industrial voltage standard at 400–480V three-phase.

At this voltage level, the Kinetix drives in the compatible family — Kinetix 5500, 5700, 6200/6500, 6000, 300/350, 2000, and 7000 — accept the 460V bus directly from the facility's industrial supply, with the drive generating the variable-frequency variable-voltage output to the motor. 

The A (230V) class is the North American 200–240V standard; the B and A variants are not interchangeable — the voltage class must match the facility supply and the drive's input rating.

At 4.5A continuous stall current, the cable sizing, connector current rating, and drive output current rating are modest.

The peak of 14.0A must also be within the drive module's peak current specification — confirming that the selected Kinetix module is rated for at least 14A output peak is the electrical verification step in drive selection.

SpeedTEC DIN Connector and IP Rating

The SpeedTEC DIN circular connector in the right-angle, 180° rotatable configuration is the cable interface that sets this motor apart from earlier Allen-Bradley servo motor generations.

The single-action locking collar engages in one turn rather than the multiple turns required by threaded connectors, which matters in production environments where motors are replaced or reconnected frequently — a connector that can be fully locked in the time it takes to make a quarter turn and listen for the click is faster to service and less likely to be left partially engaged.

The 180° rotation of the right-angle connector head is a practical cable management tool.

Before locking the connector, the head can be rotated to any of two positions 180° apart, orienting the cable exit to best suit the motor's installation direction and the cable routing path. Once the connector is locked, the cable exits cleanly in the direction chosen without strain on the cable jacket or connector shell.

Without a shaft seal, the IP protection varies with motor orientation: IP53 with shaft pointing down, IP51 horizontal, IP50 shaft pointing up.

These ratings reflect the angled motor housing drainage geometry — a downward shaft allows gravity to drain any water that enters through the shaft gap; a horizontal or upward shaft orientation allows water to pool against the shaft seal area.

When the installation environment requires higher protection — coolant spray, wash-down cleaning — an appropriate shaft seal upgrades the rating to IP66 across all mounting orientations.

The shaft seal is a separately ordered accessory; confirm the correct seal part number from the MPL series installation documentation for the specific shaft diameter and motor variant.

Class H Insulation and the Kinetix Drive Ecosystem

Class H insulation — rated to 180°C winding hotspot temperature — provides the thermal margin that continuous industrial duty requires. In normal operation at rated continuous stall current, 40°C ambient, and adequate motor housing heat conduction, the winding temperature runs well below the 180°C limit.

Class H creates the buffer against elevated ambient conditions, thermal cycling, and brief overload periods without the winding temperature approaching the degradation threshold.

The MPL-B320P-SJ72AA operates within the Allen-Bradley Kinetix motion control ecosystem through its onboard memory — the motor stores its own identity parameters, which the Kinetix drive reads at startup through the motor feedback interface.

This auto-identification eliminates the need for manual motor parameter entry at the drive: the drive and motor negotiate their compatibility and operating parameters automatically, reducing commissioning time and preventing parameter mismatch errors that can damage motor or drive in systems where motor type parameters are set manually.

Compatible drive platforms span the full Kinetix family from the compact Kinetix 300/350 single-axis modules through to the Kinetix 7000 high-power multi-axis systems, giving the MPL-B320P-SJ72AA a broad installation base across Allen-Bradley's integrated motion control architecture.

FAQ

Q1: What is the difference between the SJ72AA and MJ72AA connector/encoder variants of the MPL-B320P?

The two letters before "72AA" define encoder type and connector style.

The SJ variant carries a single-turn high-resolution encoder, which provides absolute position within one revolution — the drive knows the angular position immediately at power-up but requires a homing routine to establish position across the full axis travel after power interruption. 

The MJ variant carries a multi-turn high-resolution encoder, which retains absolute position across multiple revolutions through power loss, eliminating the homing requirement entirely. The connector type (72 = SpeedTEC DIN, right-angle) is the same on both variants.

Choose SJ when homing at startup is acceptable; choose MJ when absolute multi-turn position continuity is required.

Q2: What IP rating does the MPL-B320P-SJ72AA achieve without a shaft seal, and when is the shaft seal needed?

Without a shaft seal, the IP rating depends on mounting orientation: IP53 with shaft pointing down, IP51 horizontal, IP50 shaft pointing up. These ratings cover typical dry industrial environments and light contamination.

When the motor will be exposed to coolant spray, cutting fluid mist, or routine wash-down cleaning, an appropriate shaft seal kit must be installed — this raises the IP protection to IP66 across all mounting orientations.

The shaft seal is an additional accessory and is not included with the motor. Always confirm the shaft seal part number from the MPL installation documentation for the specific motor variant before ordering.

Q3: Which Kinetix drive is the correct match for the MPL-B320P-SJ72AA?

The MPL-B320P-SJ72AA at 4.5A continuous stall and 14.0A peak current is compatible with Kinetix 5500, 5700, 6200/6500, 6000, 300/350, 2000, and 7000 drive modules in the 460V class.

The specific drive module selection depends on the application: number of axes, bus architecture (shared DC bus vs. individual axis), communication protocol (EtherNet/IP vs. SERCOS), and system power requirements. 

The drive module's continuous and peak output current ratings must accommodate the motor's 4.5A continuous and 14.0A peak demands. The onboard motor memory allows auto-identification — the Kinetix drive reads the motor's parameters directly from the motor at startup when using a compatible feedback cable.

Q4: Does the single-turn encoder require a homing routine at startup?

Yes, for multi-turn absolute position. The single-turn encoder knows the angular position within the current motor revolution immediately at power-up — no movement is required to establish within-turn position.

However, it has no record of how many full revolutions have occurred since the last power cycle. If the axis can move during power loss, or if the application requires accurate absolute position across the full axis travel after power-up, a homing routine must be executed to establish the axis reference position.

If eliminating this homing step is a requirement, the multi-turn encoder variant (MJ suffix) provides true multi-turn absolute position that survives power interruptions without a homing traversal.

Q5: What are the key installation and commissioning checks for the MPL-B320P-SJ72AA?

Confirm the drive module is rated for 460V AC input and verify the output current rating covers the 14.0A peak requirement before connecting.

Rotate the motor shaft by hand to confirm smooth bearing operation before installation. 

If shaft seal is required for the IP rating, install it before coupling the motor to the machine — the seal cannot be fitted after the coupling hub is installed without disassembly. Engage the SpeedTEC connector fully until the locking collar clicks — partial engagement of the DIN connector is the most common field installation error and presents as erratic encoder feedback or intermittent drive faults.

After connection, verify motor auto-identification at the Kinetix drive during the initial power-up sequence, and confirm the rotor inertia parameter displayed by the drive matches the 0.000078 kg·m² specification before executing the first motion command.