Refrigerant compressor motor control

Abstract

Abstract A REFRIGERATION SYSTEM HAVING AN ELECTRIC MOTOR DRIVEN RECIPROCATING COMPRESSOR IS PROVIDED WITH A MOTOR PROTECTION AND CONTROL SYSTEM. THE MOTOR PROTECTION AND CONTROL SYSTEM INCLUDES A MOTOR CURRENT SENSOR FOR SENSING MOTOR CURRENT, A TEMPERATURE SENSOR FOR SENSING DISCHARGE GAS TEMPERATURE FROM THE COMPRESSOR AND A THERMOSTAT FOR SENSING ROOM TEMPERATURE. THE SIGNAL PROVIDED FROM THE CURRENT SENSRO IS SUMMED WITH AN OPPOSITE POLARITY RESET SIGNAL AND INTEGRATED TO PROVIDE AN INPUT SIGNAL TO A FIRST TRIP CIRCUIT. WHEN THE INPUT TO THE FIRST TRIP CIRCUIT EXCEEDS A PREDETERMINED VALUE, A SOLID STATE SWITCH MEANS DEENERGIZES A RELAY WHICH DISCONNECTS THE MOTOR FROM THE LINE CURRENT SOURCE. THE TEMPERATURE SENSOR IS CONNECTED TO A SECOND TRIP CIRCUIT WHICH IS ALSO CAPABLE OF DE-ENERGIZING THE RELAY AND THE MOTOR IN THE EVENT OF AN EXCESSIVE TEMPERATURE CONDITION. THE THERMOSTAT IS CONNECTED TO A THIRD TRIP CIRCUIT IN A MANNER SUCH THAT OPENING OF THE THERMOSTAT CONTACTS DE-ENERGIZES THE SOLID STATE SWITCH AND RELAY. CLOSING THE THERMOSTAT CONTRACTS PASSES A SIGNAL THROUGH THE SOLID STATE SWITCH MEANS TO ENERGIZE THE RELAY PROVIDED THE SWITCH HAS BEEN RESET TO THE CONDUCTING CONDITION. FEEDBACK MEANS ARE PROVIDED RESPONSIVE TO THE NON-CONDUCTING CONDITION OF THE SWITCH TO RAISE THE OUTPUT OF THE INTEGRATION CIRCUIT AND ADDITIONAL FEEDBACK MEANS ARE PROVIDED RESPONSIVE TO THE NONCONDUCTING CONDITION OF THE SWITCH TO DECREASE THE THRESHOLD OF THE TRIP CIRCUITS. THE FEEDBACKS PROVIDE A RESET LEVEL FOR THE SYSTEM WHICH IS LOWER THAN THE INITIAL TRIP LEVEL AND TO IMPROSE A TIME DELAY ASSOCIATED WITH THE FIRST TRIP CIRCUIT ON RESETTING THE SYSTEM AFTER A TRIP DUE TO OPENING THE THERMOSTAT CONTACTS. D R A W I N G

Inventors

• 👤 D Neill

Bibliographic Details