Switch Information

The Vacuum Electric Switch Co. is offering this switch in three different versions to improve restrike resistance during capacitor switching.  The improvements in restrike resistance are achieved by first adding grading capacitors and second by increasing the open gap between the vacuum contacts from 0.160 to 0.320 inches.

The geometric configuration of this switch may result in the parasitic capacitance in parallel with each vacuum interrupter being unequal.  This is most likely to occur when this switch is used on poles where objects in close proximity may cause a larger portion of the recovery voltage to appear across the upper module and reduce the switching capability.  Grading capacitors tend to equalize the capacitance across each vacuum interrupter diminishing this effect.  The recovery voltage withstand capability is further improved by increasing the contact open gap from 0.160 to 0.320 inches.  The larger gap requires more energy than is available from a solenoid mechanism so that it is only possible on motor operated switches.

The common uses of this 34kV switch are either capacitor switching or sectionalizing.  It can have either a solenoid or motor operated mechanism.  The principal differences between switches with the two mechanisms are the complexity of control, control current demand, available operating voltages, and mechanical life.   A motor operated switch requires a simple control system because the control current is less than 6 amperes and is available with a variety of control voltages.  The VES motor operator has a limited life of approximately 30,000 operations as compared to the 200,000 operations for  the solenoid operator.  A solenoid  operated switch requires a peak operating current of 120 to 130 amperes for 1½ cycles which may be difficult to supply.  This problem may be overcome by using a stored energy control such as shown here.

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