When the rectifier is turned off, which type of voltage remains in the system up to the breaker?

The correct answer is AC Voltage, which remains in the system up to the breaker when the rectifier is turned off. In cathodic protection systems that utilize a rectifier to convert AC (Alternating Current) to DC (Direct Current), the rectifier's primary function is to supply the necessary DC for effective corrosion prevention.

When the rectifier is powered down or turned off, the DC supply ceases, but the AC voltage that is upstream of the rectifier remains. This is due to the nature of how rectifiers operate; they only convert the input AC voltage to DC when they are active. The AC voltage is still present until it is interrupted further up the line at the breaker.

Understanding this distinction is crucial for maintenance and troubleshooting, as any remaining AC voltage can pose a safety hazard when working on the system. Recognizing the differences among the other types of voltage is also important: pulse voltage typically refers to short bursts and is not what remains when the rectifier is off, high voltage generally indicates voltages above standard levels but doesn't specifically refer to what's left in the system post-rectifier operation.