Experimental study on arc duration under external transverse magnetic fields in a DC 580V circuit

Using transverse magnetic field (TMF) is one of the most important ways to improve the electric life and the breaking capacity of DC relays. In order to better understand the influence of transverse magnetic field on arc duration, a series of experiments were conducted under external transverse magnetic field with 4 relay contacts in a DC 580V/60A circuit. Using permanent magnets, the transverse magnetic field is obtained and the magnetic flux density at center magnet can be varied from 80 to 320 mT. The results show that the making arc duration is independent of magnetic flux density, but the breaking arc duration is decreased monotonically with the increase of the magnetic flux density. In addition, the gradient |Δt/ΔB| of the breaking arc duration is decreased with the increase of the magnetic flux density, which means the curve of tB tends to be flat.