Comet Self-Lubricating System Service Manual
Service Bulletin-18 | Vacuum Capacitors
Self-Lubricating System for
Air-Cooled Capacitors
Comet AG Service Bulletin-18 | Vacuum Capacitors
Herrengasse 10 | CH-3137 Flamatt Self-Lubricating System for Air-Cooled Capacitors
T +41 31 744 95 00 | pct@comet.tech Issue date: 27-OCT-2020
pct.comet.tech Page 1 of 4 Replaces: 22-SEP-1994
The letter "A" in a Comet capacitor nomenclature (as for instance in CVMA-650AA/55-AAB) indicates that the
capacitor is air-cooled. In the same way "C" indicates convection cooling and "W" indicates water cooling.
In air cooled capacitors, air is forced to pass along the inside of the bellows where it can be considerably
heated up. The air then passes through the inside of the drive mechanism, thereby heating up all the parts of
the drive mechanism including the lubricant itself. The air eventually exits through holes centered around the
red cap. The hot and dry air causes the lubricant to dry out faster. This also increases the viscosity of the lubricant, thereby causing it to be rubbed off.
Years ago, Comet developed the self-lubricating system as shown in the enclosed sketch to prevent these disadvantages of air-cooled capacitors. It consists of a grease reservoir with a piston that is actuated whenever
the drive screw is turned, thereby pushing the lubricant between drive screw and drive nut.
The Comet self-lubricating system may increase the life of an air-cooled capacitor by a factor of two to five!
There is no change in the outline or in the installation procedure. The presence of a self-lubricating system in
an air-cooled capacitor is indicated by adding a "P" to the type designation, for instance:
CVMA-650AA/55-ABB air cooled, standard
CVMA-650AA/55-ABB-P air cooled, self-lubricated
Since the price difference between the two types is minor, we recommend to always using the self-lubricated
version whenever it is available.
Comet AG Service Bulletin-18 | Vacuum Capacitors
Herrengasse 10 | CH-3137 Flamatt Self-Lubricating System for Air-Cooled Capacitors
T +41 31 744 95 00 | pct@comet.tech Issue date: 27-OCT-2020
pct.comet.tech Page 2 of 4 Replaces: 22-SEP-1994
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