Dr. Kesorn Pechrach Weaver: Arc Control in Circuit Breakers: The Effect of Magnetic Forces on Arc Control

Dr. Kesorn Pechrach Weaver: Arc Control in Circuit Breakers: The Effect of Magnetic Forces on Arc Control:  The Effect of Magnetic Forces on arc control The magnetic forces on the arc root increase as the arc current increases. The contac...

The Effect of Magnetic Forces on Arc Control

 The Effect of Magnetic Forces on arc control

The magnetic forces on the arc root
increase as the arc current increases. The contact gap has a minimal influence on the
magnetic forces on the arc root. The magnetic forces on the arc root are mainly
dependent on arc current.

The different is the influence of the shapes of the
contacts are modelled. From the experimental results in Section 4.3.1, Chapter 4, the
Ag/C on the moving contact causes a longer delay in the tip of the moving contact.
An Ag/C step and Ag/C flat on the fixed contact are used to compute the magnetic
forces on the arc root, see Figure 3.19, Chapter 3.

The material of the arc runner is Cu and it is 1.0 mm thick. The material of the
contact is Ag/C (95/5 %) and 0.8 mm thick. The anode is on the moving contact and
the cathode is on the fixed contact.
A Silver/Graphite contact pad with a step to the surface of the arc runner is shown in
Figure 5.4. A Silver/Graphite contact pad flushes without a step to the surface of the
arc runner is shown in Figure 5.5.

Reference: Arc Control in Circuit Breakers: Low Contact Velocity Paperback – January 1, 2017 by Dr Kesorn Pechrach PhD (Author)

Variable factors in Arc Control

Variable factors

To investigate the influence of Ag/C contact
materials on the arc root motion from the contact
region, a piece of Ag/C is welded on the fixed and
the moving contact when the anode and cathode
power supply are set in the fixed and moving
contacts.
To inspect the influence of the short circuit current
level on the arc root commutation from the contact
region, three levels of the short circuit current are
expected: 500 A, 1400 A and 2000 A. The Capacitor
Discharge System (CDS) is charged up with
capacitor 47.4 mF, inductor 224 μH and resistance
30 mΩ [2].

Reference: 

Arc Control in Circuit Breakers: Low Contact Velocity