Compressor with flooded start control

A system comprising:

• a compressor for a refrigeration system, the compressor having a suction chamber and a lubricant sump containing a mixture of liquid refrigerant and a lubricant;
• a duct assembly, located in the lubricant sump, that includes a duct frame and a sensor unit, the duct frame providing an enclosed path for evaporating the liquid refrigerant from the mixture in the lubricant sump to the suction chamber of the compressor,
• the sensor unit having at least one diode, the sensor unit being configured to:
• in response to receiving measurement signals, obtain temperature measurements of the mixture within the lubricant sump with the at least one diode;
• and
• in response to receiving a heat signal, heat and evaporate the liquid refrigerant located within the duct frame of the duct assembly with the at least one diode;
• and
• a control module that includes a processor configured to execute instructions stored in a non-transitory memory, wherein the instructions include:
• supplying a first measurement signal to the sensor unit;
• receiving a first temperature measurement from the sensor unit;
• supplying the heat signal to the sensor unit;
• supplying a second measurement signal to the sensor unit;
• receiving a second temperature measurement from the sensor unit;
• determining a temperature change of the mixture based on the first and second temperature measurements;
• determining whether the temperature change corresponds to an expected temperature change for the lubricant;
• determining whether the liquid refrigerant remains present within the lubricant sump of the compressor after supplying the heat signal to the sensor unit based on the determination of whether the temperature change corresponds to the expected temperature change for the lubricant;
• in response to determining that the liquid refrigerant remains present within the lubricant sump, prohibiting operation of the compressor;
• and
• in response to determining that the liquid refrigerant does not remain present within the lubricant sump, operating the compressor.