DEVELOPMENT OF A MATHEMATICAL MODEL FOR STUDYING THE TRANSIENT STARTING PROCESSES OF AN INDUCTION MOTOR WITH AN INDUCTION RHEOSTAT IN THE PHASE ROTOR CIRCUIT

Abstract

The task of improving the reliability of lifting and handling equipment in today's economic environment remains a pressing one. Crane mechanisms, drawing mills, and rope machines are an incomplete list of equipment used at enterprises in various industries, and, as a rule, they are outdated. Particular attention should be paid to crane lifting and handling mechanisms that operate under shock loads, high vibration, and are exposed to aggressive environmental influences.
 Unfavorable operating conditions of the equipment lead to frequent repairs and systematic downtime. In this regard, a number of requirements are imposed on crane mechanisms: high fault tolerance, ease of maintenance, and reasonable price. These requirements are partially met by electric drives (ED), which are equipped with asynchronous motors with a phase rotor and additional resistances in the rotor circuit. As the latter, complete resistance cells with additional contact equipment are often used.
 Many years of experience in the operation of such installations shows that the use of such ED on crane mechanisms leads to a number of negative consequences: 1) reduction of the reliability of the ED due to the use of power switching equipment; 2) the need to periodically involve repair personnel to maintain contact equipment; 3) increase in the weight and dimensions of the ED.
 In the current situation, improving the reliability of crane equipment is an urgent task that can be solved by using induction rheostats in the phase rotor circuit of the IM. This approach eliminates the contact equipment in the rotor and avoids the use of a stepwise switching system for starting resistances, and, due to the nonlinear electromagnetic parameters of the IR, ensures a smooth start of the IMP with a given current. The resulting power losses in the rotor circuit are carried out beyond the IM volume. In this case, the mechanical characteristic of the IMP acquires the desired excavator type.