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Enkelt Eng

NFO Sinus
 Patented technology for controlling motors.

NFO Drives Logga

With the NFO Sinus frequency inverter you can control the speed of electrical motors for machines, fans and pumps. The NFO Sinus frequency inverter is unique in that it controls motors with our own patented technology, meaning that it is interference free, which brings with it a multitude of unique benefits.

The NFO inverter is today installed in a range of different environments, from the industrial and agricultural sectors, schools and residential buildings and in large number of hospitals.

Sinus Switch

NFO Sinus generates no switching noise in the motor. This results in a silent environment.

Compare with PWM* –  PWM technology generates a high-frequency switching noise in the motor which is very irritating for both people and animals.

Sinus Switch – this is how it works: The switch connection in every motor phase consists of two transistors, a coil and two capacitors as well as logic controllers and regulators for control.

The transistors switch so that the current waveform in the coil is triangular, switching on at zero current (i.e. soft switching) and off at full current. The capacitors function as a buffer so that the current going to the motor remains even.

A regulator in the switch circuit estimates the transistors’ timing so that the voltage to the motor equal its sinusoidal set Point.

Sinus switch
  • No shielded Cables Existing unshielded cables can be used and in older facilities there is no need for any rewiring.  In addition there is no requirement for EMC classed installation accessories, for example screw fittings and switches. Therefore installation is quick and you do not have expensive EMC class cables, so the cost of installation remains low.Compare with PWM – all PWM inverters must be installed with EMC classed shielded cables and all installation accessories must be EMC classed. NFO Sinus complies with the EMC directive without a filter or shielded cables for all environments, from the industrial and agricultural sectors to residential buildings and hospitals.

  • No complicated installation requirements
    There are no special EMC restrictions when it comes to NFO Sinus installation.Compare with PWM.
    – Tough requirements are in place for laying cables and the installer must often have special EMC skills. No limitations on distance between motor and inverte. With NFO Sinus you can have a greater distance between motor and inverter – several hundred metres. The inverter can be placed centrally in an easy-to-service location – exactly where you want it. The only limitation is the cable’s resistance. Compare with PWM* – The maximum distance between the inverter and the motor varies between different PWM inverters but is often limited to a few tens of metres.



  • No electromagnetic interference
    NFO Sinus nus provides sinusoidal voltage which means that the inverter is interference free – without any electromagnetic interference. Compare with PWM* –  In PWM inverters the voltage is cut up into small pulses, which can lead to electromagnetic interference (both in cables and airborne)

  • No irritating switching noise
    With NFO Sinus there is no switching noise in the motor and giving silent and pleasant surroundings for both people and animals. Compare with PWM* – When the current is switched in the transistors there is an irritating, high-frequency noise inside the motor.


  • No bearing currents
    NFO Sinus does not give rise to any bearing currents and therefore the motor has a longer life span. Compare with PWM* – PWM technology creates electrical charges which wear the bearings in the motor. The sparks created make holes in the ball bearings. The motor bearings are therefore worn out quickly – sometimes within months.


  • No earth currents
    NFO Sinus is free from earth currents therefore making it possible to use circuit breakers for both personal safety and fire prevention. No stray currents are generated and you avoid both interference with technological equipment and an unpleasant experience for animals.

    Compare with PWM* – PWM inverters have such a high earth current that it is difficult to install them in a facility with circuit breakers and completely impossible with safety circuit breakers. Note also that the earth current increases with use of shielded cables, which is always required when installing PWM inverter

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