Capacitor Switching and Why We Use Contactors

Capacitor switching forms part of the VolTrak system, this is controlled by a off the self SIEMENS or Moeller P.L.C that switches capacitor contactors using the BCD method depended on voltage & phase angle, we have employed the latest in microprocessor controls to do this and as a result can offer superior voltage asymmetry but have stuck with traditional technology for capacitor switching for the following reasons:

• Its Field serviceable !! , is down time important to you? its better for the end user to have seperated components NOT a intergated controller ie:
  capacitor switching – power supply – P.L.C , If a thyristor , power supply , or CPU fails in a intergrated controller you have ONE option .. take it back to the manufacturer.
• By limiting the current at switch-on with the use of anti-resonance inductance that suppress any inrush peak current and the 5th harmonic that is created when switching capacitors. This relieves stress on the contactor and capacitor and we offer a 3 year warranty on contactor failure for this reason.
• Its proven technology that we have used since 1998 with NO maintenance issues that’s why major manufacturers like ABB, Siemens , and Schneider all use capacitors contactors to switch capacitors !
• Contactors are simple to replace, available everywhere, easy to fault find. Contactors are more rugged and less influenced by external transient voltages that can displace the zero point switching ( ref: IEC 146- 2 ) and cause thyristors to misfire. 

We can offer and have used the thyristors method in the past, but the contactor method when applied correctly is a lot easier to fault find and far more forgiving with regards to adverse conditions.. but don’t take our word for it ask one of our customers !

D.E.C Lake toolibin, R37/480a converter,installation date 1994,photo taken 2010