Surge Protection

Surge transients from lightning indirect strikes, utility switching, and large load disconnections on factory distribution systems inject kilovolt-scale impulses onto AC mains — propagating into dock PFC, DC bus capacitors, and downstream control electronics if inadequately attenuated. Floor-flush charging installations with long conduit runs from remote electrical rooms present elevated exposure; multi-pad aisles share feeders where one surge event affects parallel docks.

SiCore surge protection coordinates with overvoltage and isolation design — MOVs and gas discharge tubes clamp differential and common-mode impulses while preserving safety ground integrity and limiting follow-on current that could weld contacts or trip upstream breakers.

01Protection topology

• Type 2 SPD at dock AC inlet or upstream panel — rated for installation location and expected lightning exposure class.
• Tiered clamping: GDT for coarse protection, MOV for energy absorption, TVS for fast edge on control boards.
• Common-mode choke before Y-cap network — prevents surge current splitting unpredictably across facility ground.
• PFC pre-charge and inrush limiters — coordinate timing so surge recovery does not falsely trigger overcurrent.
• Signal port protection: surge-rated Ethernet and CAN transceivers with external GDT where cable runs exceed 30 m.

02Installation and grounding

Effective surge protection requires short, low-impedance path from SPD to facility ground electrode — SiCore installation guides specify maximum lead length from dock AC disconnect to building ground and prohibit shared neutral-only returns for surge current. Pit installations bond dock frame, liner, and SPD earth to the same electrode system evaluated during site audit.

Underground conduit ingress may introduce capacitive coupling — surge tests on installed mockups validate that pit moisture and rebar proximity do not elevate dock controller stress beyond type-test conditions. Post-surge behavior requires dock to enter safe idle state, log event with timestamp, and permit controlled restart after inspection — not immediate auto-resume at full power.

03Testing and maintenance

Immunity validation per IEC 61000-4-5 with 1.2/50 µs wave applied through coupling network — combined test of PFC, inverter disable, and communication survival. MOV aging from repeated clamping events reduces protection margin — SiCore recommends periodic inspection interval in high-lightning regions and documents SPD module replacement in maintenance schedules. Surge event counters in dock firmware support predictive maintenance for facilities with historical transient issues.