IMPROVING THE RELIABILITY OF PROTECTION AGAINST SHORT-CIRCUIT CURRENTS BY ELIMINATING INTERFERENCE IN THE FORM OF STARTING CURRENTS OF ELECTRIC MOTORS

The problem of increasing the reliability of protecting low-voltage electrical networks from short-circuit currents by creating a new function in the releases of automatic switches - blocking protection when starting electric motors is considered. Identification of the starting mode is based on the use of the properties of the power function of the electrical circuit - the time dependence of the sum of the squares of the instantaneous values of the currents of the three-phase circuit. This makes it possible to reliably (in parallel by two methods) determine the value cos of the mode of the protected circuit. Blocking of protection at start-up of electric motors allows you to significantly reduce the current settings of the circuit breakers in order to ensure both, the protection of the backup of the downstream circuit breaker by the superior one, and the protection of long lines from remote short circuit currents.