Reliability and safety of load-lifting cranes of the bridge type which has especially fulfilled normative service life are substantially defined by a level of their equipment devices and devices of safety, major of which are carrying capacity limiters and parameters registrars of work of the crane.
Now for used in the industry noncontrollable crane asynchronous electric drives development of the carrying capacity limiters with use of modern programmed microcontrollers and indirect methods of measurement of weight of a lifted cargo is perspective on the basis of informative parameters of the asynchronous motor.
The mathematical model of the electric drive of the mechanism of rise has been developed. The opportunity of realization of the carrying capacity limiter for cranes of bridge type with use of an indirect method of measurement of cargo weight is proved on mathematical model and by experimental researchs. The informative parameter is revealed and experimentally confirmed (rotation frequency n) with which help it is possible with sufficient accuracy to determine weight m of lifted cargo on linear function or consisting of linear pieces to the characteristic n=f (m) which enter in memory of the microcontroller directly on the crane, allows to take into account its specific features, such as transfer number of the mechanism, frequency rate of tackle, efficiency of the mechanism, etc. The mathematical model of the mechanism of rise of the electric crane and the carrying capacity limiter is developed and researches of their teamwork are carried out. The way of definition of rotation speed of the motor on vibration diagrams of the stator frame of motor without the speed sensor is offered and checked experimentally up, allowing to determine with sufficient accuracy rotation frequency of the motor and to calculate weight of a lifted cargo.
The article is admitted to the International Scientific Conference «Innovation Technologies», Thailand ( Pattaya), 20-28 February 2008, came to the editorial office on 12.12.07