Eddy current field in cup-type contact of vaccum interrupter with axial magnetic field is analyzed by finite element method with a simplified axial symmetric model. Spatial distribution of phase shift time between axial magnetic field and source current is studied. Afterwards

effects of contact design parameters on the phase shift time are analyzed. It is found that radial distribution of the phase shift time looks like the right part of parabola that has a maximum value. The phase shift time increases linearly with radius at the contact edge. The axial distribution of phase shift time is nearly a straight line at center of contact. But the distribution changes significantly near the contact edge. At middle position of the coil

the axial distribution looks like an irregular sinusoidal curve

and at edge of the contact

the distribution is a parabola with a minimum value. It is shown that the phase shift time increases linearly when contact gap decreases

reduces monotonically with decrease of contact diameter

increases linearly with increase of contact thickness

and increases sharply when contact material changes from CuCr50 to CuCr25. Coil thickness and height have little effect on the phase shift time.