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Drives technology has changed rapidly over the last few years. thanks to the progress made in the field of power electronics, variable frequency drives are now common. they offer high efficiency and a good power factor and thereby help operators to save energy. the frequency converters used to regulate them however supply the grid with harmonics and thereby impair the power quality. Industrial distribution networks often therefore display high loads with harmonics – under certain circumstances, even the standards for the point of coupling with the public grid are violated.


Impermissible disturbances in power quality can have serious consequences: if a sensitive device, such as an electronic control unit, is damaged by harmonics, this may result in problems extending right up to production failure. Further power quality challenges are reactive power, load unbalance and flicker. Active filters can reliably and highly accurately compensate for these disturbances. they take the strain off the grid, extend the service life of devices and increase the safety of industrial systems.


Active filters ensure clean grids in a whole host of sectors and applications, for example:


  • Chemical industry

  • Offshore platforms and ships

  • Steel plants

  • Water treatment and pump stations

  • Paper industry

  • Oil and gas

  • Mining

  • Power generation from renewable sources

  • Automotive industry

  • Larger printing plants

  • Cranes

  • Data centres

An Active Impact in The Grid

This slogan is based on the following line of thought: if both reactive power and harmonics in a low voltage distribution board are fully compensated for, only active power is obtained from the grid. this explains the name active filter which stems from active power filter. Active filters make this possible because they function as a regulated current source. they compensate for disturbances in the grid by feeding (phase opposite) a current of just the frequency and amplitude needed.




The GRIDCON® ACF series is the fourth generation of active filters from power Quality (PQ) division. the new devices offer the level of reliability and safety you would expect – even beyond standard operational voltages and under demanding environmental conditions (e.g. offshore). they are also optimized with regard to operation and installation. Even if this simplifies many things, the comprehensive and personal service of Power Quality remains – from the first network analysis to the final parameter setup for the filters.

Everything Professionals Need: Designed for Practical Use

  • Operation up to 690 v and higher at full power without derating

  • High power density and compact design

  • Low losses

  • Overvoltage category III up to 1000 v – even in grids with isolated star point (It network configuration)

  • Various applications:

    • Dynamic reactive power compensation up to large systems with 3 Mvar and more

    • Filtering harmonics up to the 51st order

    • Load balancing

    • Flicker compensation



Development of the fourth generation of filters built on the vast amount of experience PQ has acquired in the design and operation of passive and active filters. the result is a well-thought-out and modular concept, enabling smooth use in the various network voltages around the world, short delivery times and good reliability.

Consistently Modular Concept Cuts Costs and Delivery Times

A cabinet contains up to four power modules with a rated current of 125 A at operational voltages of up to 690 v. the compensation power can be sized accordingly and gradually extended using additional modules or cabinets. standardizing the components ensures short delivery times and cuts costs. Further savings can be made if active filters are combined with systems for passive reactive power compensation.

High Stability, Short Service Times

The modular structure makes the GRIDCON® ACF series resilient to errors. should a module fail, the other units can continue to function and will bridge operation until the error is rectified. Diagnosis of disturbances is also well-thought-out. the system's operating statuses are recorded on an sD memory card in the controller. If necessary, the data can be read out and sent to pQ for evaluation. the system is furthermore designed such that individual components can be quickly and easily replaced by the operator.

3-Level Technology – Low Losses and High Overvoltage Capacity

At the heart of the GRIDCON® ACF active filter lies a 3-level IGBT circuit – illustrated and explained in detail on page 13. Compared with inverters, which are based on a 2-level architecture, the output current of a 3-level device displays less ripple. the effort involved in output current smoothing and disturbance suppression can therefore be reduced and there are fewer losses. Furthermore, series connection of IGBTs in a 3-level filter translates into considerably higher overvoltage capacity. As well as higher voltages, this also opens up the possibility of compensating for harmonics of an even higher order. they do however require greater effort for control and monitoring than the 2-level variant. GRIDCON® ACF therefore has an intelligent protection concept. For example, each power module has an integrated, multi-stage inherent monitoring function.


Quality for the Medium-Voltage Grids

The switchgear for low and medium voltage are often in separate locations. to allow for smooth measurements in medium-voltage grids, the MIO measurement unit can also be located outside the active filter cabinet and connected with it using a standard network cable. the current inputs of the MIO can be overloaded and are very resistance to overvoltages. Applications at higher voltage levels usually mean higher power levels. GRIDCON® ACF delivers 3 Mvar and more per system and is therefore also suited to dynamic medium voltage applications.




Intuitive Operation by Touch Panel or Across the Network

The central operating and display element of the GRIDCON® ACF is a touch panel on the front of the cabinet. this has a clear menu structure and can display data in both tables and diagrams. the benefits of the touch panel include:

  • The "home" view, featuring the main information, can always be accessed

  • Simple programming of filter function with input instructions

  • Explanations and status messages in plain text

  • Language can be changed at any time

  • Password protection

GRIDCON® ACF can also be operated via the web. A standard ethernet network cable makes the filter Internet-ready. It can therefore be incorporated in a TCP/IP company network and read out or parameterized remotely using a browser.

Quick and Easy Rectification

An SD memory card in the controller contains the operating system and files used to log the system operation. the logs saved on the SD memory card can be read out during servicing. software updates and modified sets of parameters can also be easily loaded from the SD memory card onto the filter. there is no need for elaborate and costly on-site error analysis.



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