You are checking the supply chilled water temperature thermistor probe on a high-pressure hermetic centrifugal chiller. Using the illustrated chart, what statement is true if the supply water temperature is verified 45°F with a digital thermometer? Illustration GS-RA-48

Illustration GS-RA-48: the U.S. Coast Guard has not released this illustration.

Question

You are checking the supply chilled water temperature thermistor probe on a high-pressure hermetic centrifugal chiller. Using the illustrated chart, what statement is true if the supply water temperature is verified 45&deg;F with a digital thermometer? Illustration GS-RA-48

Illustration GS-RA-48: the U.S. Coast Guard has not released this illustration.

Accepted Answer

Option D: When checked with control power on and the thermistor probe connected into the circuit, the thermistor probe voltage drop should be 3.805 volts.. Thermistors operate as active circuit components; measuring their voltage drop requires control power to be energized with the sensor connected. Based on chiller control logic charts for a 45°F reading, the expected operational voltage drop across the sensor is 3.805 volts.