Celem's product range includes medium frequency induction heating power capacitors and high frequency induction heating power capacitors, configurable assembly systems for power capacitors, transformers and capacitors for use in high-voltage smoothing and bypass and of course custom-design tank capacitor solutions for any and every high-power resonant technology application.

Conduction-cooled Power Capacitors

In 1963 Celem designed the first low voltage conduction cooled power capacitor. Until this time all power capacitors were cooled by immersing the terminals and dielectric in an oil bed and water-cooling the oil. In contrast, the conduction-cooled capacitor uses the same bus bar connection that provides its electrical connection to transfer away the heat dissipated within it. This approach yields an enormous reduction in volume per unit power as well as being simpler and cheaper for manufacture. Celem's conduction-cooled power capacitors remain to this day the unchallenged market leader in the high-frequency induction heating market.

Assembly Systems

When building a large induction heating installation, a need often arises for the combination of multiple capacitors in series or parallel to obtain the required capacitance, power and voltage ratings needed for the system. In order to help our customers avoid much head-scratching, trying to re-invent the wheel, Celem designed several modular assembly systems ourselves. These systems allow the combination of capacitors in a variety of ways, and even allow hot-swapping of capacitors during usage to change operating frequency.

Water-cooled Power Capacitors

Conduction cooling capacitors requires water-cooling of the bus bars to which the capacitor is connected. While this is the logical solution in a capacitor bank composed of many capacitors in series or parallel, when a single capacitor is used it makes more sense to integrate the cooling into the capacitor itself. This approach became possible after Celem began producing capacitors based on a polypropylene dielectric, and provides the customer with a ready-to-go solution at a lower cost than an assembly system. High Operating Temperature / UHF Power Capacitors While polypropylene technology surpasses mica for specific power, mica has a much higher operating temperature than polypropylene and no frequency limitation. For an operating environment above 85°C or frequencies beyond 1MHz, mica capacitors provide a solution which is far cheaper than the ceramic technology that dominates this market.

Mica Power Capacitors

This dielectric is characterised by:

• a low loss angle (tan δ < 5x10^-4)
• a dielectric constant that is independent of temperature
• flexible operating temperature range (works at over 200°C)
• reasonable thermal conductivity
• good dielectric constant (k=8), allowing higher capacitances per unit volume

Celem historically began its product range by manufacting mica power capacitors. Today, mica technology has been surpassed for the most part by polypropylene, and many legacy Celem mica products can be replaced by cheaper and superior polypropylene equivalents (such as CPRI400P that replaces CPRI300). Today our mica product range consists primarily of high temperature mica power capacitors.

Polypropylene Power Capacitors

The dielectric used in most of Celem's products, polypropylene provides a number of advantages :

• higher power rating per unit volume
• allows construction of self-healing capacitors
• simpler to manufacture

High Voltage Capacitors

Celem sells a range of polypropylene high voltage high current capacitors, known as the CHT series.