METHOD OF PROTECTION OF PUMP ELECTRIC DRIVE Russian patent published in 2002 - IPC

FIELD: mechanical engineering; pumps. SUBSTANCE: proposed method of protection of pump electric drive in case of liquid delivery break at inlet comes to measuring electric parameters of electric drive, forming signal which controls switching off of set, comparing the signal with preset value and switching off the set. Active power is used as electrical parameter. Control signal is formed proportional to product of voltage amplitude value and instantaneous value of current corresponding to amplitude value of voltage at this moment. Preset value of operating active power of electric drive is used as set value. Signal for switching off the set is supplied with delay whose value is changed depending on time interval between end and repeated beginning of liquid delivery breaks at pump inlet. Time interval between end and repeated beginning of delivery breaks is compared with preset value. If time interval is smaller that preset value, delay of supply of set switching off signal is reduced in proportion, and when delay is zero and coincides with preset value of delay time of forming of set switching off signal at constant delivery breaks, signal for switching off set is sent when value of control signal is less than preset value. Invention is aimed at prevention of false signals for switching off electric drive in case of delivery breaks. EFFECT: improved reliability and accuracy at operation in different wells without necessity of additional adjustment. 1 dwg