In terms of cad cell operation, what does a decrease in resistance signify?

A decrease in resistance in a cad cell, which is commonly used in oil burners to monitor flame presence, signifies high light intensity. Cad cells operate based on the principle that they change resistance in response to the amount of light the flame emits. When the flame burns brightly, it produces a high amount of light, leading to a reduction in the resistance of the cad cell.

This mechanism allows the burner control system to determine whether the flame is present and functioning properly. If the cad cell detects a high light intensity, indicated by low resistance, the system confirms that the burner is operating effectively and that the flame is stable. This is critical for ensuring safe operation, as the absence of flame would lead to a higher resistance and could indicate issues such as inadequate fuel supply or other operational failures.

In contrast, low light intensity would result in increased resistance, which could trigger a shutdown of the burner for safety reasons. Therefore, the interpretation of cad cell resistance and light intensity is essential for the safe and efficient operation of oil burning systems.