Abstract
The paper presents an analysis of operating currents and torques during self-starting of motors with a voltage of 6 kV for cases of short circuit in the head feeders from the main step-down substation and in the feeders to the most distant substations of mining enterprises. For the network under consideration, the characteristic modes are: short circuit on the buses of shop substations. For the mining industry when selfstarting asynchronous motors with a squirrel-cage rotor and synchronous motors with asynchronous startup, the current multiplicity will be determined by the duration of the power failure (run-down duration). It has been established that the acceleration of motors during self-start will be somewhat slower than the usual start, since self-start begins at a speed of 0.89–0.94 of the synchronous speed and a resistance torque is equal to 0.65–0.75 of the maximum motor torque. The self-starting time of the motors is from 9 s to 42 s. To ensure self-starting conditions in the most severe modes in mountain conditions, it is necessary to make changes to the protection settings presented in the work.
Highlights
An urgent and important task is the introduction of automatic start, for which it is necessary to analyze the characteristics of the "engine - technological unit" starting unit
The power supply interruption time is the sum of the short circuit disconnection time on the supply line and the ASR operation time at the substation [4-9];
The break time consists of the time for disconnecting the short circuit on the buses from the main step-down substation (MSDS) and the time of the ATS at the workshop substation
Summary
An urgent and important task is the introduction of automatic start (self-start), for which it is necessary to analyze the characteristics of the "engine - technological unit" starting unit. The peculiarities of the operation of these units do not allow theoretically calculating the characteristics of selfstarting. It is necessary to carry out experimental studies of start-up and run-down of units. It is in the course of calculating the actual self-starting currents according to the experimental characteristics and comparing them with the relay protection data that will make it possible to determine the possibility of selfstarting [1-3]
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