DMI DC motors

Reliability with less maintenance

The DMI DC motor provides higher output performance over a wide speed range and is easier to maintain compared to conventional DC motors. Unique features and a robust design increases motor reliability and extends the time between maintenance intervals. The power dense low-profile of the DMI DC motor also makes it easy to integrate into almost any existing application.


  • Extended speed range capabilities with superior commutating performance
  • Longer brush wear lengths compared to conventional designed brushes
  • Reduced commutator diameters resulting in lower peripheral speeds and extended brush life
  • Precise bearing tolerances preventing the risk of grease leakage into the motor
  • High quality bearings with long lubrication intervals
  • Mechanical brush wear monitoring system – no special monitoring probed brushes required


  • IEC frame sizes 180, 200, 225, 250, 280, 315, 400
  • Power up to 1400 kW Torque up to 22.000 Nm
  • Voltage up to 810 V
  • IM – horizontal or vertical, foot or flange
  • IP – 22-55
  • IC-06, 17, 37, 86W, 666, 410
  • Class 200 Insulation
  • Meets standards IEC, CE, CSA (up to 710 V)

High output and small dimensions

Higher Output and Torque

A number of new solutions - patents applied for several of them by ABB - have together given the DMI motors such a superior performance that they are in a class of their own in the DC market. The development work on the stator, for example, has provided more space for the windings and led to a more uniform temperature distribution due to a more compact coil design and improved manufacturing processes.

The biggest difference however, has been achieved within the design of the armature core laminations. Arranging the cooling ducts below the winding slots provides two important factors:

  • Removes heating losses during full load current conditions
  • Provides for a fully symmetrical distribution of the magnetic flux path within the armature core

High output over a wide speed range

Peak Performance

The fundamental qualities of the design of the DMI motors have led to a marked increase in the top speed without affecting the service reliability.

The core and winding losses are kept at a low level also at high speeds. This is the result of radially small armature winding slots and amply dimensioned magnetic circuit.

The design work was also focused on increasing the stability of the commutator and reducing its diameter. A smaller diameter gives a lower peripheral speed which ensures proper functioning of the brushes at the highest speeds. In addition vibrations are kept at a low level.

Movements in the coil-ends are prevented by robust supporting rings below the armature coil-ends and by using a massive shaft to prevent its deflection.

Features of the DMI:

  • Higher torque quality at low speed
  • Higher power and torque
  • Higher power at top speed
  • Higher speed

Smooth running at low speeds and low moment of inertia

Higher Torque Quality at Low Speed

DMI-skewed-slotsAn optimized armature design allow the DMI motor to produce full power over extended speed ranges. Placement of the coils within the core slots and the precise slot skew allows for smooth torques transitions and improved commutation as compared to older DC motor technologies.

Benefits of DMI and reduced maintenance

Reduced maintenance and spare parts

A low level of maintenance is an important customer requirement as well as the ability to predict required maintenance during scheduled shutdowns. The DMI motor design has incorporated many features that will extend the periods between scheduled maintenance intervals and easy access to brush exchanges and brush monitoring. Described are a few items below:

  • Optimum commutation characteristics and extended speed ranges within minimum sparking beneath the brushes
  • Extended brush wear lengths on all brushes
  • Superior commutator performance and stability
  • Optimized commutator diameters that reduce peripheral speeds and improved brush wear
  • Precise fit tolerances between bearing parts that will eliminate grease leakage into the motor
  • Easy access greasing of both bearings
  • Filtered blower assemblies that have high resistance to contaminants resulting in reduced maintenance requirements
  • Clear and precise maintenance manuals available for all products
  • Mechanical brush wear monitoring system – no special monitoring probed brushes required

ABB Spare Parts & Logistic Services guarantees fast and reliable availability of spare parts throughout the world.

You can also contact us directly at

Success stories



DMI 400 replaces LAD 710 at Comital
Comital is a rolling mill manufacturing aluminum foil. Located just a few minutes away from the motor factory in Västerås, Sweden.  In 2008, Comital changed an LAD 710 from the 70's to a new DMI 400V. Despite its smaller size, the DMI motor  delivers both higher power output (900 kW) and wider speed range (800-1700 rpm).



DMI DC motor goes underground
A model of long hole production drilling rigs, Simba W6 C, operates in what are the world's largest underground iron ore operations. The mines Kiruna Mine and Malmaberget, located in the northern part of Sweden, supply about four percent of the world's steel industry.

A DMI 180 operates the rig's water pump. The new water pump system has reduced power consumption and water spillage, which lowers the overall cost and is more environmental friendly. The DMI was  was selected for its small size and high performance.




DMI on top of the world
During the construction of one of the world's tallest buildings, the International Commerce Centre in Hong Kong,. the construction crane in operation on top of the skyscraper  used a DMI motor. The winch and control system for the crane were delivered by one of ABB‘s customers in Denmark, Krøll Cranes. The motor drives the main hoist of  aconstruction crane.

The motor operating on the crane is a DMI 250.  Delivered in 2005, the motor performed non-stop. The high power output of the motor in relation to its size and a wide speed range  strongly contributed to Krøll Cranes decision to use ABB’s  DMI motor.



DMI for increased productivity in South Africa
A South Africa aluminium rolling mill wanted to reduce the thickness of an aluminium strip from 0.6 mm to 0.03 mm. To do that they required motors that could delilver increased mill speed. The mill selected ABB’s DMI motors because they offer high power output and a wide speed range. For the application ABB delivered two DMI 850 kW, 400Z motors jointed together in a tandem set.

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