Motorized Capacitors

Comet Motorized Capacitors offer the latest integrated drive technology for vacuum capacitors at the best price-per­formance ratio. A single communication protocol for RS232 and RS485 provides flexibility in a wide range of applications.

Motorized Capacitors are the ideal solution for high-precision operation. Besides ensuring highest accuracy, motorized capacitors simplify procurement with an easy-to-install subsystem.
The core component of the Universal Motorized Capacitor is a Comet variable vacuum capacitor, mounted with an insulating cover, coupler and stepper-motor. A durable, backlash-free Comet-coupler connects the capacitor to the drive system. Integrated flanges ensure easy mounting in the system. Appropriate high-voltage insulation between the capacitor and the flanges is also included.


  • Accurate alignment of variable vacuum capacitor and stepper-motor and a durable, backlash-free coupling result in long, consistent lifetime
  • Assembled solution for easy installation
  • Highly accurate repeatability of capacitance positioins
  • Lower total cost of ownership


  • One driver PCB for new Integrated Drive (ID-400 and ID 1200)
  • Same communication Comet protocool RS232 and RS485
  • Flexible baud rate between 9.600 and 115.200 Bd
  • Connect up to 32 modules in RS485 mode
  • Readout of full-step, micro-step and capacitance position
  • Capacitance table with higher resolution on request

Integrated Drive Solutions

Capacitor tuning

Using a stepper-motor, the capacitance of the variable capacitor can be tuned precisely between user selectable limits.

High-level commands

The module can be controlled from a PC or a control board using high-level commands (RS232, RS485). The communication protocol allows the execution of the following commands:

  • Precise motion control by setting full-step, micro-step or capacitance position
  • Set idle and drive current, speed and slave address within allowed range
  • Read out of actual full-step, micro-step and capacitance position
  • Read out of actual full-step, micro-step and capacitance position
  • Read out of characteristic capacitance curve (C-Curve)
  • Read out of various parameters such as firmware version, serial number and all customer and factory limits
  • Comprehensive RX responses (ACK, NAK):
     - ACK for all commands
     - ACK for «movement-started» resp. «movement completed»
     - NAK e.g. check-sum error, index out of range
  • Baud rate can be set within 9.600 to 115.200 Bd
  • Set user limits (Cmin and Cmax) within factory limits
  • Store up to 10 user selectable positions

Further technical information can be found in our Service Bulletins SB-60, SB-63, SB-64 and SB-69.

Capacitor Series with Integrated Drive

Two sizes of integrated drive systems are available for different capacitor series.
Here our recommendations:


The Semiconductor Standard



The first choice for
200 mm applications



High frequency,
long lifetime



Higher Capacitance
at Higher Voltage


More Capacitors

Variable VC


Fixed Capacitors


Trimmer VC




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