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Switching devices especially suited for capacitor switching are essential for reliability. As an example, the devices should be such that restriking during breaking operations (which may result in high over-voltages) cannot occur. The operating experience of Roederstein MKP capacitors since their introduction in 1978 has shown their excellent behaviour whilst being switched.

High output densities and reduction of losses have resulted in reduced resistance of modern MKP capacitors. Switching capacitors, especially switching capacitors in parallel with others already energized, causes high in-rush currents. As a consequence, the life of contactors and also capacitors will be affected.

For capacitor banks without filter reactors, it is recommended that the following precautions for reduction of in-rush current be adopted.

• Use only capacitor contactors with series resistors, switched in during closing and then disconnected when circuit is closed.

• B & J contactors are purpose designed having superior damping behavior and coils suitable for operation up to 90°C.

• Circular switching mode.
• Four-quadrant operation.
• Zero voltage tripping.
• 12 switching programs.
• Adjustable CosØ range: 0.85 to 0.95 cap
• Display of C.T. secondary current.
• High resistance to faults due to mains harmonics.
• Automatic or manual operation.
• Fault alarm in the display and by potential-free relay contact.
• Easy setting of parameters via keyboard.
• Switching delay times-manual or automatic
  self-setting.
• Connection to C.T. 5Amp or 1Amp

For test purposes, capacitors may be switched in or out manually at any time, even when using the automatic option mode.

The Roederstein MKP capacitor is a metallised polypropylene film capacitor with self-healing properties. The over pressure tear-off fuse prevents the capacitor from bursting caused by inadmissible electrical or thermal overloads.

Excellent heat dissipation and constant capacitance over extended periods are due to the natural oil impregnant, which is hermetically sealed under vacuum. When compared to "block" type capacitors in plastic enclosures, the Roederstein capacitor is far superior and can withstand case temperatures of 65°C. It will also provide superior performance and longer life even in the presence of harmonics.

  Technical Data Roederstein capacitor