This invention relates to a formulation comprising a compound of formula where R1 is hydrogen, methyl, ethyl, propyl or butyl; R2 is methyl or ethyl; R3 is hydrogen, methyl or ethyl; and n is 1, 2 or 3; to the use of a compound of formula as a solvent; and to certain novel compounds of formula. A current drive unit drives the motor at an axis current value of a rotating coordinate system that rotates in accordance with a control angle that is a rotational angle used in a control. An outer jacket serves to prevent gas leakage. When the present state is the confirmation-requiring state, the controller displays on a display screen a confirmation window for confirmation of power shut off.