| 摘要 |
The present invention involves control and protection circuit (7) for a compressor motor (ML) which includes an inductively activated contactor for controlling the flow of current to the compressor motor. The circuitry of the pr esent invention includes a plurality of current detectors (12) associated with each ph ase winding of the compressor motor for sensing the current in each phase winding. T he sensed currents are combined in a predetermined manner and used to provide protection against an overcurrent condition (15), single phase operation (13) an d light loading condition (14). Additional detector circuits are also connected to the p resent control and protection circuit to provide protection against high temperature in the compressor motor windings (16), high temperature in various component of the compressor motor (18), and undervoltage in the power supply (30). A temperature detector (T4) disposed inside the cooling chamber also provides for cycling of t he compressor motor to maintain the temperature in the cooling chamber at within a predetermined temperature range. The inductive coupling is activated by a protec tion timer (20) and an oscillator (22). The protection timer deactivates the oscillat or when a trip signal is received from the detector circuits. A predetermined time delay is provided by the protection timer to prevent spurious trips of the compressor mot or.
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