Which grounding scheme uses a resistor to limit fault current?

Which grounding scheme uses a resistor to limit fault current?

• A. Resistance grounding
• B. Solid grounding
• C. Reactance grounding
• D. Ungrounded

Answer: (A)

Limiting fault current with a resistor in the grounding path is the key idea. In resistance grounding, the system neutral is connected to earth through a high-value resistor. When a ground fault occurs, current can flow to ground but is kept at a small, controlled level by that resistor. This reduces the energy of the fault, protecting equipment, lowering arc-flash risk, and allowing protective relays to detect and respond to the fault without exposing the system to a full short-circuit current. This approach differs from solid grounding, where the neutral is tied directly to ground and fault current can surge to the full available short-circuit level; from reactance grounding, which uses an inductor to limit current but introduces reactive effects and different fault behavior; and from an ungrounded system, which has no intentional path to ground, making fault currents and fault detection behave differently.

Limiting fault current with a resistor in the grounding path is the key idea. In resistance grounding, the system neutral is connected to earth through a high-value resistor. When a ground fault occurs, current can flow to ground but is kept at a small, controlled level by that resistor. This reduces the energy of the fault, protecting equipment, lowering arc-flash risk, and allowing protective relays to detect and respond to the fault without exposing the system to a full short-circuit current.

This approach differs from solid grounding, where the neutral is tied directly to ground and fault current can surge to the full available short-circuit level; from reactance grounding, which uses an inductor to limit current but introduces reactive effects and different fault behavior; and from an ungrounded system, which has no intentional path to ground, making fault currents and fault detection behave differently.