FIELD: electrical engineering. SUBSTANCE: method involves detection of capacitance between contacts of commutator in off state in coordinate to be measured or in two adjacent coordinates, generation of first information parameter, which corresponds to alternation of capacitance in vicinity of measured coordinate. First claim of invention describes method in which capacitance between contacts of device is measured as first derivative of capacitance with respect to coordinate. Second claim of invention describes method in which this capacitance is measured as difference between said adjacent coordinates. Then method involves storage of this capacitance value as function of time, selection of time for scaling of capacitance function of reference and tested devices, detection of capacitance between contacts of tested device in moment when contact passes point which coordinate is used in measurement. Capacitance function of time is used for generation of second information parameter which corresponds to its alternation in vicinity of measured coordinate as first time derivative of capacitance according to first claim of invention or as interval between duration of contact movement between said adjacent coordinates according to second claim of invention. Speed of mobile contact is judged by ratio of information parameters. EFFECT: increased speed and decreased number of preparation and recovery work. 3 cl, 2 dwg
