Estun · AC servo motors

Same power, different character.

The EM3 family offers the right rotor for every mechanism in three inertia classes: 50 W to 7.5 kW, up to a 23-bit absolute encoder, IP65/IP67 body and 3× peak torque.

Pick a motor, see the set Compare the series
Estun EM3A EM3A Low inertia
Estun EM3J EM3J Medium inertia
Estun EM3G EM3G High inertia
50 W – 7.5 kWpower range
23 bit8,388,608 counts/turn
3×peak torque vs rated
IP65/67EM3J IP65 · EM3A IP67

Three inertia classes

Choose the rotor for your mechanism

Low inertia

EM3A

Slim, long rotor with the lowest own inertia. On fast start-stop axes it spends its energy on the load.

50 W – 5 kW 3000 rpm rated 40 – 130 mm flange 17 / 20 / 23 bit

Ideal for: Flying shear, packaging, robotics, pick-and-place

Build a set with this series

Medium inertia

EM3J

General-purpose series balancing speed and stability; easy to tune on medium-inertia loads.

0.2 – 1 kW 3000 rpm rated 60 – 80 mm flange 17 / 23 bit IP65

Ideal for: Conveyors, linear modules, general automation

Build a set with this series

High inertia

EM3G

The thick rotor's flywheel effect damps load steps; high torque at 1500 rpm rated speed.

0.85 – 7.5 kW 1500 rpm rated 130 – 180 mm flange 17 / 23 bit

Ideal for: CNC, woodworking, winders, press feeders

Build a set with this series

Engineering note

Inertia matching decides controllability

On a fast start-stop packaging axis a thick-rotor motor spends its energy turning its own rotor and heats up; choose EM3A here. On a CNC with fluctuating load a slim rotor lets the tip oscillate; choose EM3G for the flywheel effect.

≤ 10 : 1inertia ratio for belt drives
≤ 5 : 1for precision ball screws
Calculate the inertia ratio with the servo sizing tool
EM3A, EM3J and EM3G rotor inertia compared: acceleration and response to a load step (qualitative) ROTOR SPEED RESPONSE TO THE SAME COMMAND load step EM3A low inertia · 3000 rpm EM3J medium inertia · 3000 rpm EM3G high inertia · 1500 rpm fastest acceleration least deviation on a load step - - - speed command Qualitative illustration, not a measurement. The real response depends on load inertia and tuning. © 2026 ONX Control. All rights reserved. This animation may not be copied or reused without permission. Source: https://www.onxcontrol.com/en/products/estun/em3 ONX Control ONX Control · https://www.onxcontrol.com © 2026 ONX Control. All rights reserved. This animation may not be copied or reused without permission. Source: https://www.onxcontrol.com/en/products/estun/em3 https://www.onxcontrol.com/en/products/estun/em3 ONX-44F871A9 © ONX Control · onxcontrol.com
EM3 encoder resolutions: 17-bit 131,072, 20-bit 1,048,576, 23-bit 8,388,608 counts per turn; multi-turn position kept by battery HOW MANY COUNTS PER TURN? 17 bit absolute · multi-turn 131,072 counts / turn 364 counts / degree 20 bit incremental 1,048,576 counts / turn 2,913 counts / degree 23 bit absolute · multi-turn 8,388,608 counts / turn 23,302 counts / degree MULTITURN TURN COUNT 1286 1287 1288 1289 1290 mains power battery active Turn count survives a power cut via the battery cable: no homing needed © 2026 ONX Control. All rights reserved. This animation may not be copied or reused without permission. Source: https://www.onxcontrol.com/en/products/estun/em3 ONX Control ONX Control · https://www.onxcontrol.com © 2026 ONX Control. All rights reserved. This animation may not be copied or reused without permission. Source: https://www.onxcontrol.com/en/products/estun/em3 https://www.onxcontrol.com/en/products/estun/em3 ONX-44F871A9 © ONX Control · onxcontrol.com

Encoder options

8.4 million counts per turn

The 23-bit absolute encoder gives vibration-free rotation at low speed and surface quality on CNC. Absolute (multi-turn) encoders keep the turn count during a power cut via the battery cable; no homing at power-up. The 20-bit incremental encoder suits economical axes with a homing routine.

Model code

EM3A-08ALA242 explained

T = 17-bit absolute (multi-turn), F = 20-bit incremental, L = 23-bit absolute (multi-turn).

Specifications

Torque, current and inertia

PowerFlangeRated / peak torque (Nm)TorqueRated current (A)Inertia 10⁻⁴ kg·m² (brake)
0.05 kW40 mm0.159 / 0.557
0.90.023 (0.027)
0.1 kW40 mm0.318 / 1.11
1.10.043 (0.047)
0.2 kW60 mm0.637 / 2.23
1.50.147 (0.179)
0.4 kW60 mm1.27 / 4.46
2.90.244 (0.276)
0.75 kW80 mm2.39 / 8.37
5.10.910 (1.07)
1.0 kW80 mm3.18 / 9.54
6.91.14 (1.30)
1.5 kW · 200 V100 mm4.78 / 14.3
9.52.33 (3.10)
2.0 kW · 200 V100 mm6.37 / 19.1
12.62.95 (3.72)
1.5 kW · 400 V100 mm4.78 / 14.3
4.92.33 (3.10)
2.0 kW · 400 V100 mm6.37 / 19.1
6.42.95 (3.72)
3.0 kW · 400 V130 mm9.8 / 29.4
10.57.72 (9.00)
4.0 kW · 400 V130 mm12.8 / 38.4
13.010.2 (11.6)
5.0 kW · 400 V130 mm15.9 / 47.7
15.914.0 (15.4)

Dark bar rated, light bar peak torque. IP65/IP67, class F insulation, 24 V DC brake.

Cable selection

The right cable for each motor

  • N / Bpower cable: N without brake, B with brake
  • A / Iencoder cable: A absolute (battery), I incremental
  • -05 / -05RXlength suffix; RX is flexible cable for cable chains

Example: EM3A-08ALA242 (brake, 23-bit, waterproof) → EC3P-B8718-05 + EC3S-A1724-05. The configurator matches this automatically.

Motor groupConnectorPower cableEncoder cable
EM3A 50–400 WwaterproofEC3P-N/B9718EC3S-A/I1724
EM3A / EM3J 0.75–1 kWwaterproofEC3P-N/B8718EC3S-A/I1724
EM3A / EM3J 50 W–1 kWplasticEC3P-N/B9118 · 8118EC3S-A/I1124
EM3A 1.5–3 kW · EM3G 0.85–1.8 kWlarge frameEC3P-N/B9314EC3S-A/I1924
EM3A 4–5 kWlarge frameEC3P-N/B9319EC3S-A/I1924
EM3G 2,9 kWlarge frameEC3P-N/B8214EC3S-A/I1924
EM3G 4.4–5.5 kWlarge frameEC3P-N/B9212EC3S-A/I1924
EM3G 7.5 kWlarge frameEC3P-N/B9211EC3S-A/I1924

With ED3L / ED3S drives. 1, 3, 5, 10, 15, 20, 25 m standard and flexible (RX) lengths.

Calculate the right motor

Sizing and motion software

Engineering tool

Servo motor sizing

Calculate torque, speed and inertia ratio from the motion profile of a ball screw, belt, conveyor or rotary table, and see the matching EM3 motors.

Size a motor
ONX software

X Motion Library

Power, S-curve positioning, homing, electronic gearing and modulo blocks for EtherCAT CiA 402 axes in CODESYS. Used with ED3L drives in our flying shear and rotary knife projects.

Explore X Motion
ONX software

X CNC Library

CNC path planning and interpolation for CODESYS (G-code, look-ahead feed planning, corner smoothing); it passes axis targets through X Motion to EtherCAT drives such as ED3L.

Explore X CNC
Servo configurator Enter your torque, your EM3 set is ready Motor, ED3L drive, power and encoder cable and I/O connector, with part numbers and list prices. Open the configurator

FAQ

About EM3 motors

How does a 23-bit encoder differ from 17-bit?

A 17-bit encoder divides one turn into 131,072 counts, a 23-bit encoder into 8,388,608; about 364 versus 23,302 counts per degree. It gives smoother rotation at very low speed and a better surface finish on CNC.

What is the battery for on an absolute encoder?

A multi-turn absolute encoder keeps the turn count during a power cut thanks to the battery encoder cable (EC3S-A…) or the ED3S battery box; no homing is needed at power-up. The drive warns when the battery is low.

Is an IP65/IP67 motor suitable for washdown?

EM3A body and connectors are IP67, EM3J is IP65; the shaft exit is not covered. Ask for the oil-seal option where there is cutting fluid, oil spray or pressure washing.

What should the load inertia ratio be?

The ratio of load inertia (referred to the motor shaft) to motor inertia should stay up to about 10 on belt drives and below 5 on precision ball screws. Enter the load inertia in the configurator to check it automatically.

Let's choose the right motor together

Tell us about your application and power requirement; our engineers will get back to you.

Prefer to talk now? +90 216 504 14 42