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Vacuum Capacitors

Handling precautions


Before use

  1. Meiden vacuum capacitors are properly packed for airfreight shipping. Carton box on the outside and polystirine containers on the inside are used. If capacitors have been exposed to rough handling or extended storage period it is recommended that end user checks capacitance and withstand voltage before installation. Capacitors can withstand impacts of up to 294 m/s2. Never drop the capacitor. Handle capacitors with care.
  2. To prevent flashovers, wipe the ceramic part of the apacitors with cloth (dry or wet with alcohol) to remove moisture and dust.
  3. Do not use solvents containing chlorine (e.g.: trichloroethane). If dust or contaminants stick to any other parts, wipe them off with dry cloth.

Mounting vacuum capacitors

  1. When installing vacuum capacitors in equipment, make sure not to apply any bending stress greater than 1225 Ncm. In particular when supporting the capacitors on both fixed and moving sides, mounting fittings on either side should be made of a soft material in flexible structure in order to protect the capacitors from thermal expansion and external stress.
  2. When using a motor to turn the capacitors use flexible coupling to prevent the lateral load to the capacitance adjustment shaft. When using an inflexible coupling, a central misalignment of up to 0.2mm is permissible. A greater misalignment may result in irregular turns and misalighment.
  3. When an optional guide bearing (available separately) is used for the VM type capacitors, it is delivered mounted on the capacitor. It will be attached to the capacitor with two screws (diagonally to each other) guaranteeing optimal position which ensures that central alignment of the capacitance adjustment screw isbest possible. Do not remove and reinstall guide bearing by yourself.
  4. If you want to use a guide bearing of your own design, it should be designed based on the premise that a misalignment of a maximum of ±1mm may remain between the capacitance adjustment screw and the M5 taps.
  5. The maximum allowable torque of the M5 taps on the fixed and moving sides is 147 Ncm and that of the M4 taps is 71.6 Ncm. Tighten the taps to lower the torque values.

Using vacuum capacitors

  1. The maximum allowable vibration level of the capacitors is 98 m/s2. Do not apply greater vibration levels to the capacitors.
  2. When the surface temperature of the capacitors exceeds 125 C, an abnormal current may be carried. If the surface temperature is expected to rise high, use optional water-cooled flanges.
  3. Do not place a metal object with an electric potential close to the sides of the ceramic envelope of the capacitors, as it may affect the capacitors and generate a flashover. Secure a sufficient space around the ceramic envelope.
  4. Do not use the capacitors in environments where corrosive gases (particularly sulfur and chlorine) or dust may exist. The surface of the capacitors may give rise to discoloration, or in some cases the properties of the capacitors may be affected.

Small "Thump" noise … Anything wrong?

A "collision" noise may be generated when the ceramic center pin, located inside the capacitors, hits both ends. It is sometimes heard when the capacitance adjustment shaft is rotated in vertical orientation. There is, however, no problem in actual performance.


Squeaky sound

A squeaky sound may be generated when the ceramic center pin in the capacitors slides when capacitor is rotated. This sound is acceptable and causes no problem in capacitor performance.


Product types


Custom-ordered vacuum capacitors

Omnicor has a variety of vacuum capacitors for custom applications. We will try to accommodate your special requirements where possible.


Provision of technical information

  1. This catalog contains only a portion of technical information we have available. We shall, on request, provide technical data sheets, dimensional drawings and frequency vs.current characteristics for all vacuum capacitors.
  2. In you are purchasing vacuum capacitors make sure your technical specifications and drawings are up-to-date because they are subject to change for product improvements without prior notice.