Reason:

(1) The emergency stop button is being pressed.

(2) Poor insulation of the excitation coil

(3) Insulation failure of blower motor

(4) Insulation failure of transformer

Solution:

(1) Check that all emergency stop buttons are not pressed.
Click here for details. E.STOP causes and methods of investigation

(2) (3) (4) Check the timing when the leakage current detector is activated.