2. Short-circuit current breaking phenomena
2.1 Parameters dominating short-circuit current breaking

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Short-circuit current interruption occurs at the prospective current zero after the contact separation of an usual circuit-breaker in an ac circuit. The success or failure of the interruption is dominated by:

• Peak Value of the short-circuit current
  
• di/dt --- Rate of change of the current before the current zero
  
• dv/dt --- Initial rate of rise of TRV across the contacts
  
• Peak Value of TRV
  
• Arc quenching power --- Blasting gas pressure between contacts, Contact shape, Number of series connected breaking Points, etc.
  

The predominant factors affecting the phenomena just around current zero are di/dt, dv/dt, and the blasting gas pressure. The author experimentally has obtained the following equation. :
dv/dt=Kp^a(di/dt)^b
for SF₆ GCB a=2.68, b=-2.24
for ABB a=1.60, b=-1.30
These values are obtained experimentally and statistically. The image to define the critical boundary is shown in Fig. 2.1.
di/dt is calculated in Section 1. dv/dt is the main subject of this Section.

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This page is based on Prof. E.Haginomori's lectures in Tokyo Institute of Technology, and edited by Japanese ATP User Group. Copyright (C) Eiichi Haginomori and Japanese ATP User Group.