Motorized Capacitors

Motorized Capacitors are the ideal solution for high-precision operations where 100 % accuracy is required. In addition, motorized capacitors replace manual assembly with a standardized, easy-to-install subsystem.

The core component of the Motorized Capacitor is a Comet variable vacuum capacitor, which includes an insulating cover, coupler and stepper-motor to drive the capacitor. A durable, backlash-free Comet-coupler connects the capacitor to the drive system. Assembled flanges ensure easy mounting in the system. Appropriate high-voltage insulation between the capacitor and the mounting flanges is also included.

Information, such as a measured capacitance table, is stored on the memory chip. Certain versions (Expert, Expert 2) can be controlled using high level RS-232/485 commands that enable the user to reference the capacitor at Cmin (homing), set the capacitor to a specific capacitance or move the capacitor by a certain number of steps in either direction.

Benefits for System Designers

  • Accurate alignment of variable vacuum capacitor and stepper-motor results in long consistent lifetime
  • A durable, backlash-free coupling connects the capacitor to the drive system
  • Assembled solution for easy installation
  • Integrated Slam Index or referencing
  • Highly accurate repeatability of capacitance positions
  • Reduced cost of ownership

Product Functions

Capacitor tuning

Using a stepper-motor, the capacitance of the variable capacitor can be tuned between the mechanical end stops. The stepper-motor can be driven with standard stepper-motor driver signals.

Download C-Curve

The characteristic C-Curve of the variable capacitor is stored in the ID module. It can be downloaded to a PC or a host.

Stepper-motor driver interface

The module includes a stepper-motor driver. That can be controlled with standard pulse and direction signals.

High-level commands

The module can be controlled from a PC or a control board using high-level commands. Different logical interfaces are available. The Comet proprietary protocol allows the execution of the following commands:

  • Read out of calibration data, including characteristic capacitance curve (C-Curve) and serial number of the module stored on the memory chip or within the microcontroller (depending on the 0-module) and store it in a text file on the PC.
  • Control the motion and position of the stepper-motor that drives the vacuum capacitor, reference at Cmin position; move the drive by a given number of steps or to a certain capacitance value.

More Capacitors

Variable VC


Fixed Capacitors


Trimmer VC




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