REO filters for medical technology

Suppression of conducted interference

The use of electrical and electrical equipment is becoming more widespread. However to ensure safe and reliable operation, electromagnetically compatible conditions must exist i.e. a device must be able to work satisfactorily in its electromagnetic environment and without itself causing unacceptable electromagnetic inference in the same environment.

Electromagnetic inference can cause various faults that are often difficult to diagnose. Crackling and hissing on a radio receiver, data errors and processor glitches in computer engineering and even the breakdown of isolation are all possible effects. To ensure compliance with relevant EMC directives and to avoid instances of interference, appropriate EMC filters must be used.

Electromagnetic interference can be propagated in various ways. The nature of that propagation depends on the frequency involved. EMC filters are used to suppress conducted inference by maximizing the impedance mismatch between line and load. The filtering effect works in both directions. This means that interference from the power-consuming device to the network as well as from the network to the power-consuming device is damped.

Limits on radio interference voltage

A number of EN (European norms) specify limits on radio interference voltages. These EN regulations differentiate between use in residential or light
industrial areas (Class A) and in industry (Class B). To make it easier to select the correct filter and where possible, the classification is shown in our catalogue.

Filter technology from REO

Since its foundation in 1925, REO has been helping customers regulate current and voltages. The development and manufacture of high quality inductors, helping our customers to ensure Power Quality (PQ) has played a central role in our business.

Today‘s wide range of EMC components, such as inductors, transformers and RF and Harmonic filters demonstrate our comprehensive knowledge and expertise.

This coupled with fresh ideas and innovation, enable us to provide our customers with products that provide superior functionality and reliability. We offer standard products, as well as client specific solutions in drive technology, railway engineering, renewable energy and electric transportation.

Compliance with important medical norms

  • EN 60601-1-2 VDE 0750-1-2 EMC for medical equipment
  • EN 55011 VDE 0875-11 ISM-equipment (industrial, scientific and medical)

Filter of REO

  • Comprehensive product range
  • Made in accordance with DIN EN 60931-1 and all norms relevant to EMC, such as EN 55011 and 61800-3
  • UL-certified products
  • Broad range of additional services, such as EMC Surveys, Test and Validation of components in customers own converters, site visits and inhouse test capabilities
  • Personal technical consultancy
  • Client-specific solutions
  • REOplus: REO speaks your language – our worldwide field sales offices and production facilities keep REO close to our clients at all times, so we are able to react rapidly and efficiently
  • All our products are developed and tested in accordance with DIN VDE 0565

REO filters at a glance

REO single-phase mains filters

REO single-phase mains filters achieve the highest possible damping thanks to powerful chokes.
The single-phase mains filters are available as one-stage or two-stage filters and as a result enable compliance with the EMC guidelines in relation to the limit values for your application.

Three-phase mains filters

Three-phase mains filters filter interferences in both directions – from the consumer to the network and from the network to the consumer. Typical applications are for example frequency inverters, wind turbines or power supplies

DC filter

REO DC filter for protecting solar modules against premature aging. As a result of the ever more efficient energy conversion in modern power inverters, ever more high-frequency energy is being introduced into DC circuits. This energy is caused by the quick switching operations of modern power semi-conductors and could cause the premature aging of solar modules. REO-DC mains filters work in both directions. In practical usage, this means that the end devices are protected against unnecessary high frequencies. On the other side however, the power network is also protected against the spreading of self-generated high frequencies by the end devices.

Harmonic filters

REO harmonic filters are used for the reduction of the THD (Total Harmonic Distortion). The harmonic currents will be so strongly suppressed that a THD of less than 5% is achieved (for example in uninterruptible power supply systems).
Furthermore, the reactive power is reduced by a harmonic filter (e.g. REOWAVEpassive) and up to 30% of energy is saved.

Sinusoidal filter

Sinusoidal shaped output voltage for your frequency inverter
Advantages of the REO sinusoidal filter:
– Output voltage is sinusoidal
– Also suitable for very long motor cables
– Shielded motor cables are not needed
– The efficiency level of the entire system will be increased
– Reduction of the motor noise and eddy-current losses


EMC filters are used for suppressing line-conducted interferences.

The spreading is prevented by a maximum level of impedance mismatch. The filtering effect extends in both directions. This means that both the interference from the consumer to the network and the interference from the network to the consumer are suppressed.

Du/DT Filter

REO du/dt filters suppress the voltage increase to tolerable levels due to their design. For short lengths of cable between the frequency inverter and the motor, a du/dt filter limits the increase speed and is the ideal link between frequency inverter and motor.

High-current filter

The REO high-current filter has been specially designed for the interference suppression of high-current applications in wind power facilities and industrial applications.

There are filter series for the 480V and 690V voltage levels.
REO high-current filters can be delivered in a range of housing variants and hence they can be adapted to a variety of different environmental conditions.

filter combination

With the filter combination from REO, a three-phase line choke and an EMC filter are combined. This combination will minimise EMC problems and harmonics and will reduce energy costs by up to 20%.
The line choke is responsible for removing stress from the supply network by compensating for the harmonic reactive power. In this way, the harmonics and the commutation notches in particular will be significantly reduced.

Individual solutions

Are you looking for an individual solution? No problem! Our REO experts will be happy to answer any questions you may have.