Videos module 1 – Basic principles of electrical circuit breaking

Module 1 - Basic principles of electrical circuit breaking
Module 2: Circuit breaker timing principles

These videos are intended for professionals in the electrical industry and are produced by Zensol Automation Inc..

Basic principles of electrical circuit breaking

Auxiliary contacts
ICOS synchronous command
Grading Capacitors

Basic principles of electrical circuit breaking

This video explains what happens when you break a circuit in HV and how to prevent the arc from reestablishing itself in different insulating media.

Breaking an electrical distribution or transport network permits the isolation of part of the network from the rest of it. In the high voltage field, separating the contacts is not enough to break the current instantly.
When the contacts separate, the current continues to flow and a temporary electric arc forms between the moving and fixed contacts. To extinguish the arc, the arcing current must become zero and stay at zero. By varying the opening speed and the distance between contacts, the power and duration of the electric arc are greatly affected.
Sufficient contact spacing for certain insulating media helps a lot in cooling and extinguishing the arc.

Auxiliary contacts 

The pre-insertion contacts and the signal contacts are both commonly called auxiliary contacts and it is important to know the difference between them. This video describes the difference between the two types of auxiliary contacts and their respective roles.

ICOS synchronous command 

This video describes the principle of ICOS synchronous command and when it should be used. This command is used only during controlled open and close operations, which means during intentional operations. It is also used on other devices such as shunt coils, capacitor banks and some transformers at 315 kV and 735 kV. ICOS synchronous command is an interesting alternative to eliminating certain pre-insertion contacts.

Grading Capacitors

This video explains what a grading capacitor is and when it should be used. Grading capacitors are mounted on the breaker in order to prevent any contact from being exposed to excess voltage.