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 d < 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.