With its PhaseMod family, Epcos is taking a completely new approach to power factor correction. This elegant and comprehensive solution features a high degree of integration, substantial savings in space, and the greatest ease of installation.
Optimisation of power quality and reliability of the energy supply are more important than ever. Power factor correction (PFC) in its various forms - such as static and dynamic PFC, harmonics filters and active filters - plays a key role here. PFC systems help not only to satisfy basic demands for stable energy supply and power quality, but also to save energy costs and reduce capital expenditure at the same time. Given the right design, a PFC system soon pays for itself.
The key benefits of PFC are:
* Reduced power consumption and lower costs.
* Less reactive power in the entire grid.
* Lower power dissipation.
* Reduced emission of greenhouse gases spares the environment.
* Higher power quality and lower voltage drops.
Power capacitors for PFC and accessories such as controllers, reactors and contactors have been improving power quality and raising the power factor worldwide for many years. But automatic PFC systems take up a lot of space and require high capital expenditure. Although power capacitors are key components of PFC systems, they account for only 10% to 20% of total costs.
The new PhaseMod family developed by Epcos can dramatically reduce the size and capital cost of PFC systems. It represents a completely new generation of automatic PFC equipment and PFC modules. Whereas conventional PFC systems are put together from a selection of commercially-available standard components (such as capacitors, busbars, contactors and fuses), mounted in cabinets and interconnected by cables, the PhaseMod family is a forward integration system of matching components selected and customised for PhaseMod (Figure 1) complete with the necessary connections. PhaseMod improves power quality, extends the service life of the capacitors, and increases their reliability and safety thanks to a multistage concept.
Multifunctional carrier platform
The carrier platform (Figure 2) based on sheet moulding compound (SMC) provides a stable, heavy-duty foundation of electrically insulating material that is ideal for mounting components for power distribution and power electronics. This carrier platform integrates the interconnections and copper busbars required for power distribution. It doubles as a basic platform on which all components can be mounted. In addition to all electrical connections, the carrier platform contains inserts for mechanical fastening and electrical contact with switchgear such as capacitor contactors and fuses.
The choice of a composite fibre material with reinforced fibreglass has made a low-cost solution with good technical and physical properties possible. Thanks to forward integration, PhaseMod systems require less material and fewer parts and need less space. The various integrated components were carefully selected and customised. Epcos' proven MKK AC technology with concentric windings, wavy cut, edge reinforcement and gas impregnation was improved by adding a special capacitor structure to cope with very high energy levels up to 100 kvar (Figure 3).
The high inrush currents that power capacitors have to withstand, call for heavy-duty contactors and capacitors. Special capacitor contactors with inrush current limiting are therefore used to prolong service life and improve power quality. They make use of pre-mating contacts and magnetic coupling. A fuse with a specific trigger characteristic was developed for the PhaseMod to ensure reliable protection of the capacitors. This innovative fuse is also more economical and ensures more reliable contact thanks to direct mounting.
As well as long service life and economy of operation, safety is a key parameter of power factor correction. The PhaseMod has a multistage safety system featuring: self-healing; dry technology; overpressure sensors; discharge resistors; HRC fuses for short-circuit protection; temperature monitoring of every single capacitor winding.
The PhaseMod family is divided into the A-PhaseMod series for installation in automatically-controlled PFC equipment (larger systems for up to 500 kvar) and the S-PhaseMod series that replaces a complete small PFC system. PhaseMod comprises a complete product family currently comprising over 70 standard types for voltages from 230 to 480 V, line frequencies of 50 or 60 Hz, and reactive powers from 50 to 100 kvar.
The first two series of the PhaseMod family have laid the foundation for an even more comprehensive architecture of the future that will offer more degrees of freedom for coping with PFC challenges. In view of the sharp increase in nonlinear loads and the resulting harmonics, effective countermeasures are urgently needed. For this purpose, Epcos is specially developing the AF and SF PhaseMod series, which can be detuned. These modules are suitable for use as harmonics filters as well as for classical power factor correction. The next development stage will be dynamic power factor correction based on high-speed thyristors combined with PhaseMod modules. Here power semiconductors will replace conventional contactors and likewise be integrated into the SMC carrier platform. Special attention will be paid here to power dissipation.
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