An IE3 premium-efficiency electric motor is the driving heart of a machine; yet in most applications, ordering the motor on its own is not enough. Needs such as stopping the motor, feeding back its position, cooling it at low speed, or protecting its winding against temperature are solved with accessories added at the ordering stage. A wrong or missing accessory choice means extra intervention after installation, downtime and unnecessary cost. In this guide we cover the main accessories that can be added to an IE3 motor at the order stage (electromagnetic brake, encoder, forced cooling fan, PTC thermistor and counter-flange), together with which one is required in which application, helping you build the right order code.

At HEM Motor, we deliver our IE3 and IE4 motor range from 0.55 kW to 355 kW configured with accessories according to the project. Our goal is to prepare the motor that goes to the field so that it runs the moment it is fitted to your machine, with the correct brake torque, the correct encoder type and the correct cooling method.

IE3 electric motor with brake, encoder and forced cooling fan accessories

Why Are IE3 Motor Accessories Defined at the Order Stage?

An IE3 motor's frame size, shaft end, end-shield design and terminal box are prepared at the factory according to the accessories to be added. For instance, on a motor that will carry a brake, the rear end-shield and shaft end are machined for the brake disc; on a motor that will carry a forced fan, the fan cowl is replaced with an independently supplied unit. For this reason, adding an accessory "afterwards" is often impossible or causes extra cost and incompatibility. The best approach is to clarify the load, duty type and control requirement before ordering and define the accessory accordingly.

The IE3 efficiency class itself is part of this equation: in a premium-efficiency motor, energy saving becomes meaningful under continuous operation, so the correct duty type (S1 continuous) and the correct cooling choice preserve efficiency. Reading the IE3 nameplate correctly is the first step to understanding which accessory is needed. Sizing the motor at the correct load ratio is also decided at this stage; an oversized motor lowers efficiency and may add unnecessary accessory cost.

Electromagnetic Brake: For Stopping and Holding

An electromagnetic brake is an accessory that mechanically stops the shaft or holds the load in a suspended position when the motor is de-energized. The most common type is the spring-applied (fail-safe) brake: when the coil is energized the brake opens and the motor turns freely; when power is lost, the spring clamps the brake disc and locks the shaft. Because this structure prevents the load from dropping during a power cut, it is critical for safety.

DC vs. AC Supplied Brake

Brakes can be DC (typically 24V, 96V, 178V) or AC supplied. DC brakes are more compact and allow precise control, while AC brakes can be supplied directly from the mains, simplifying wiring in some applications. The brake coil is fed from the motor terminal box or via a separate rectifier. In applications requiring fast stopping, the AC-side cut-off (fast cut) feature of the rectifier shortens the brake reaction time.

Holding Brake or Stopping Brake?

There are two basic needs: a holding brake keeps the load stationary (hoisting, elevator, crane, inclined conveyor). A stopping (dynamic) brake brings a rotating load to a stop within a defined time (door drives, fast positioning). To select the correct brake torque, the motor rated torque, the load inertia and the desired stopping time must be known. As a general rule, the brake torque is selected at least 1.5-2 times the motor rated torque; however, in hoisting applications this ratio is kept higher for safety. The brake torque selection is directly related to the motor's rated torque calculation.

On brake motors, a manual release (hand lever) option may also be requested; this is used to lower the load in a controlled way when there is no power. The order code must clearly state the brake type, brake torque (Nm), supply voltage and manual release option.

Encoder: Speed and Position Feedback

An encoder is a feedback device that converts the rotational speed and/or position of the motor shaft into an electrical signal. The drive (VFD) or controller uses this signal to control the motor in closed loop, providing high torque and precise positioning even at low speed.

Incremental and Absolute Encoder

An incremental encoder produces a fixed number of pulses per revolution (ppr); it is sufficient for speed control and relative positioning, but the position information is reset when power is lost and a return to reference is needed. An absolute encoder assigns a unique digital value to each angular position; even if power is lost, the motor shaft "remembers" where it stopped. For precise positioning, multi-axis systems and applications where a reference run is undesirable, an absolute encoder is preferred.

Which Application Needs an Encoder?

Conveyor synchronization, filling/dosing machines, printing lines, elevator and crane drives, robotics and servo-like positioning applications require an encoder. When selecting an encoder, the resolution (ppr), supply voltage (5V/24V), output type (HTL/TTL, SinCos, SSI), mounting flange and cable exit direction are specified. Encoder motors are usually sized together with the drive; therefore the compatibility of the motor voltage connection with the drive must also be checked. The encoder cable should be run separately from the power cable and shielded so that it is not affected by noise; in drive systems, grounding and EMC rules directly affect a clean encoder signal, as covered in our motor grounding and EMC content.

Forced cooling fan and encoder feedback unit mounted on an IE3 motor

Forced Cooling Fan: Cooling at Low Speed

On standard IE3 motors, cooling is provided by the bladed fan on the shaft end (IC411). The motor cools as long as its own shaft turns; however, when the motor is run continuously at low speed with a drive (for example at 20-30% of rated speed), the shaft fan cannot produce enough air and the motor overheats. This is where the forced cooling fan comes in.

The forced cooling fan (IC416 cooling method) is a separate fan unit mounted on the motor body with its own independent supply. No matter what speed the motor runs at, even when stopped, it provides a constant air flow. Thus the motor can deliver full torque continuously over a wide speed range (especially at low speeds). You can find the difference between cooling methods in detail in our IC411 vs. IC416 comparison.

Which Application Needs a Forced Fan?

Extruders, mixers, test benches, crane and conveyor drives operating over a wide speed range; all applications that carry a continuous load at low speed with a drive benefit from a forced cooling fan. At the order stage, the fan supply voltage (usually 230V/400V single or three phase), fan rotation direction and, if required, a separate thermal protection for the fan are specified. In hot and dusty environments, the forced fan should be considered together with a high insulation class and cast-iron body.

PTC Thermistor and PT100: Winding Temperature Protection

An IE3 motor winding carries a risk of burning when it heats up due to overload, phase loss or insufficient cooling. A PTC thermistor (temperature-dependent resistor) is ordered embedded in the winding and, when the winding temperature exceeds a certain threshold, its resistance rises rapidly to trigger the protection relay; the motor is thus stopped before it burns. A PT100, on the other hand, measures temperature continuously as an analog value and is preferred in plants that require monitoring/recording.

Especially in continuous heavy duty, in low-speed operation with a drive, or in high-value critical applications, PTC/PT100 protection is a strong safeguard. We detailed the winding temperature protection selection in our IE3 PTC/PT100 wiring content, and the overall thermal monitoring approach in our PT100 and PTC temperature monitoring article.

Counter-Flange, Special Shaft and Other Order Options

Accessories are not limited to electrical equipment. On the mechanical connection side there are also options to be specified at the order stage:

Building the Correct Order Code

When ordering an IE3 motor with its accessories, the following information should be provided together so that the seller can prepare a complete quote: power (kW), poles/speed, mounting type (B3/B5/B35), voltage and frequency, duty type, protection class (IP), insulation class (F/H), brake type and torque, encoder type and resolution, forced fan and its supply voltage, PTC/PT100 protection, terminal box orientation and any special shaft. To gather this information, you can use our list of information to provide when requesting a quote. We also collected the tips for requesting protection equipment together in our protection equipment purchase content.

You can review our entire IE3 range and accessory options via the HEM Motor home page, and see the application areas of IE3 motors and their service factor and overload capacity in detail.

Frequently Asked Questions

Can a brake be added to an IE3 motor later?

Although it is possible to a limited extent on some frame sizes, since the brake affects the rear end-shield and shaft-end structure of the motor, the healthiest approach is to specify the brake at the order stage. Adding it later usually brings extra labour, compatibility risk and higher cost. Clarifying the correct brake torque and supply voltage from the start ensures trouble-free installation in the field.

If I will run continuously at low speed with a drive, is a forced fan a must?

If the motor will deliver full torque continuously well below its rated speed (usually below 50%), the shaft fan cannot provide enough cooling and a forced (IC416) cooling fan is recommended. Otherwise the motor overheats and its efficiency and life decrease. In wide-speed-range applications, the forced fan together with PTC temperature protection is a safe solution.

Should I choose an incremental or absolute encoder?

If only speed control and relative positioning are sufficient, an incremental encoder is an economical choice. If the position must be preserved after a power cut, a reference run is undesirable, or high-precision absolute positioning is required, an absolute encoder should be selected. Drive and controller compatibility also determines the choice; therefore the encoder should be sized together with the drive.

Get a Quote

We deliver your IE3 motor correctly configured with brake, encoder, forced cooling fan, PTC protection and special flange options. Let us build the most suitable order code for your application together. Reach us now via our contact page or call +90 (532) 345 49 86; let our engineering team guide you to the right accessory selection.

Pre-Order Checklist

  • Have power (kW), poles/speed and duty type (S1-S6) been determined?
  • Are the mounting type (B3/B5/B35) and terminal box orientation clear?
  • If a brake is needed: type (DC/AC), torque (Nm), supply voltage and manual release option selected?
  • If an encoder is needed: incremental/absolute, resolution (ppr), output type and supply specified?
  • If there is continuous low-speed operation, has a forced (IC416) cooling fan and its supply voltage been added?
  • Are winding protection (PTC/PT100) and protection class (IP) selected according to need?
  • Are special shaft, counter-flange or special fan cowl needs noted in the order code?