In GFPE residual sensor scheme, incorrect polarity of the neutral with respect to the associated phase conductors can cause what?

In GFPE residual sensor scheme, incorrect polarity of the neutral with respect to the associated phase conductors can cause what?

• A. Normal load current detected as a fault condition, which may result in a false GFPE trip
• B. Immediate trip of the GFPE
• C. No effect on protection
• D. Delayed fault detection

Answer: (A)

In a GFPE residual sensor scheme, protection works by detecting any current imbalance between the conductors feeding a circuit. Under normal conditions the currents sum to zero, so the sensor doesn’t trip. If the neutral is connected with the wrong polarity relative to the associated phase conductors, the return current on the neutral can be viewed by the sensor with the opposite sense. This creates a nonzero residual current even though there is no actual fault, so the protection interprets it as leakage to earth and may trip. That’s why a normal load current can be detected as a fault condition, potentially causing a false GFPE trip. The other possibilities don’t align with how polarity reversal affects the residual current sensing—the issue is a spurious residual, not an guaranteed immediate trip, no effect, or only delayed detection.

In a GFPE residual sensor scheme, protection works by detecting any current imbalance between the conductors feeding a circuit. Under normal conditions the currents sum to zero, so the sensor doesn’t trip. If the neutral is connected with the wrong polarity relative to the associated phase conductors, the return current on the neutral can be viewed by the sensor with the opposite sense. This creates a nonzero residual current even though there is no actual fault, so the protection interprets it as leakage to earth and may trip. That’s why a normal load current can be detected as a fault condition, potentially causing a false GFPE trip. The other possibilities don’t align with how polarity reversal affects the residual current sensing—the issue is a spurious residual, not an guaranteed immediate trip, no effect, or only delayed detection.