Liquid level detector

A liquid level detector for use in a pump control system, the liquid level detector adapted for connection to a condensate reservoir of an air conditioning system, a refrigeration system or a heating system and comprising:

• an enclosed filling chamber for liquid;
• a liquid inlet to the chamber;
• a liquid outlet from the chamber that is connectable to a pump, wherein the liquid outlet is positioned below the liquid inlet when the liquid level detector is connected, in use, to the condensate reservoir;
• and
• a first capacitive sensor including a first capacitive sensor element forming a first capacitance that is sensitive to permittivity within a first region of the chamber proximate the first capacitive sensor;
• a second capacitive sensor spaced from the first capacitive sensor and including a second capacitive sensor element forming a second capacitance that is sensitive to permittivity within a second region of the chamber proximate the second capacitive sensor,
• wherein each of the first and second capacitive sensor elements forms a ring around the chamber;
• and
• an electronic controller configured to receive output signals indicative of an amount of liquid in the chamber from the first and second capacitive sensors and to generate a control signal for controlling the pump, wherein the controller is configured to monitor the output signals and to and generate the control signal in response to the output signals to control a speed of the pump to maintain a desired amount of liquid in the chamber, and
• wherein the controller is configured to calculate an angle of orientation of the chamber by comparison of the output signals and generate the control signal based on the calculated angle and the output signals to control the pump in response to the amount of liquid in the chamber.