Non-intrusive electronic control circuitry to detect an open protector in a hermetically sealed compressor

An electronic apparatus to externally detect open protector contacts inside of a compressor comprising:

• a compressor motor having a run winding and a start winding, the run winding and the start winding each having a first and a second winding connection, the first connection of both the start winding and the run winding electrically connected together and to a common terminal, the second connection of the start winding electrically connected to an start winding terminal, the second connection of the run winding electrically connected to an run winding terminal, the compressor motor also including internal protector contacts that open the electrical circuit to the common terminal in a protection condition;
• a contactor means for switching power to the compressor motor, the contactor means electrically connected to a source of power and to the compressor motor;
• a capacitor means for phase shifting current to the start winding, the start capacitor electrically connected between the source of power and the start winding or the run winding of the compressor motor;
• an compressor running indicator means for indicating that the compressor motor is operating, the compressor running indicator means electrically connected between the start winding and the run winding terminal to indicate a compressor running condition;
• and
• a protection indicator means for indicating open protector contacts, the protection indicator means electrically connected between the common and the start winding terminal to indicate a voltage present across the common and the start winding terminal,
• wherein the protection indicator means is also coupled to the compressor running indicator means such that the protection indicator means is disabled when the compressor is running normally and the protection indicator means is enabled and indicates when the protector contacts open inside of the compressor.

A method to externally detect open protector contacts inside of a compressor comprising the steps of:

• providing a compressor motor including internal protector contacts, the compressor motor having a common terminal, a start winding terminal, and run winding terminal;
• providing a compressor running indicator circuit to indicate a voltage across the start winding terminal and the run winding terminal;
• providing a protector indicator circuit, the protector indicator circuit to indicate a voltage across the common terminal and the start winding terminal of the compressor;
• disabling the protector indicator circuit when the compressor motor is operating normally;
• and
• indicating open internal compressor protector contacts when the internal compressor protector contacts are open and the compressor motor is not running.