What are the advantages and disadvantages of single-phase reclosing and three-phase reclosing?

Single-Phase Reclosing

Advantage:

When a single-phase-to-ground fault occurs on a line and three-phase auto-reclosing is applied, it results in higher switching overvoltages compared to single-phase reclosing. This is because three-phase tripping interrupts the current at zero-crossing, leaving residual charge voltages on the unfaulted phases—approximately equal to the peak phase voltage. Since the de-energized interval during reclosing is relatively short, the voltage on these unfaulted phases does not decay significantly, leading to substantial switching overvoltage upon reclosure. In contrast, with single-phase reclosing, the voltage on the faulted phase at the moment of reclosure is typically only about 17% of nominal (due to capacitive voltage division along the line), thus avoiding significant switching overvoltage. Long-term operational experience with three-phase reclosing in 110 kV and 220 kV networks shows that switching overvoltage issues are generally not severe on medium- and short-length lines.

Disadvantage:

When single-phase auto-reclosing is used, non-full-phase operation occurs. In addition to requiring special considerations for pilot protection, this significantly affects the setting and coordination of zero-sequence current protection, thereby preventing zero-sequence current protection on medium- and short-length lines from functioning effectively.
Three-Phase Reclosing

Advantage:

When three-phase auto-reclosing is used, the tripping circuits of all protective relays can directly actuate the circuit breaker. However, when single-phase auto-reclosing is employed, all pilot protections, phase-to-phase distance protections, zero-sequence current protections, etc.—except those inherently possessing phase-selection capability—must be controlled by the phase-selection element of the single-phase recloser before they can operate the circuit breaker.

Disadvantage:

When three-phase auto-reclosing is used, under the worst-case scenario, reclosure may occur onto a three-phase short-circuit fault. For certain lines where stability studies indicate that such reclosure must be avoided, a simple phase-to-phase fault detection element can be added to the three-phase reclosing scheme. This element prevents reclosing for phase-to-phase faults while still allowing reclosure for single-phase faults.