Mark V Circuit-Switchers

Introduction

Mark V Circuit-Switchers are especially suited for switching and protection of shunt capacitor banks. They can be fitted with optional pre-insertion inductors to minimize capacitor-bank switching transients, markedly improving power quality.

Pre-insertion inductors are more effective than controlled-closing schemes and pre-insertion resistors for limitation of:

• Inrush current and overvoltage at the capacitor bank bus — curbing induced transients in substation low-voltage circuits that can cause spurious signals, insulation puncture, and component damage.
• Switching-surge overvoltages at remote transformers — which can lead to decreased transformer life, or even failure.
• Overvoltages on long open-ended lines. Such overvoltages can cause nuisance arrestor operation.
• Transient overvoltages on users’ utilization-voltage bus — voltage magnification of capacitor-switching transients can cause nuisance tripping of adjustable-speed drives and other sensitive electronic devices.

For more information regarding transient control, refer to the technical paper titled “Selecting a Capacitor-Switching Overvoltage Control Method Effective in Preventing Nuisance Tripping of Adjustable-Speed Drives”.

Mark V Circuit-Switchers are also well-suited for transformer, line, cable, and reactor switching and protection. For more information, see S&C Specification Bulletin 711-31.