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Indonesia is one of the countries with the highest thunderstorm frequency worldwide. Every year from November to March, massive lightning strikes threaten outdoor substations, factory distribution rooms and rural power facilities. A standard grounding system is the core defense line to release surge current and prevent lightning damage for all types of transformers. Many electrical accidents in Indonesia are not caused by defective equipment, but by unqualified grounding resistance.
All top local transformer manufacturers have clear grounding guidelines for their products. Whether buyers purchase dry-type and oil-immersed transformers from PT Trafoindo Prima Perkasa, B&D Transformer, PT Sintra Sinarindo Elektrik or PT Mettakindo Dayakubus, standardized grounding construction is a mandatory procedure to meet PLN grid access requirements.
| Grounding Resistance Range | Current Operation Status | Lightning Strike Resistance | Applicable Project Suggestion |
|---|---|---|---|
| Below 4Ω (Qualified) | Leakage current and lightning surge can be released instantly | Excellent, fully compliant with PLN safety regulations | Urban substation, large industrial park and coastal projects |
| 4Ω ~ 10Ω (Passable) | Basic protection available, weak against continuous thunderstorms | Medium, suitable for low-risk inland areas | Ordinary small factories and residential power supply zones |
| 10Ω ~ 20Ω (Unqualified) | Slow current discharge, easy to cause instantaneous overvoltage | Poor, easy to trigger protection tripping during thunderstorms | Need immediate grounding optimization and resistance adjustment |
| Above 20Ω (Dangerous) | Lightning current cannot be discharged, direct burnout risk | Extremely dangerous, zero lightning protection capability | Forbidden to put into operation for any PLN-related projects |
The humid soil in rainy seasons will reduce grounding resistance appropriately, while dry dry-season soil makes grounding performance worse. Electrical engineers suggest testing grounding resistance every quarter, especially before the thunderstorm season. Cooperate with local manufacturers to match supporting grounding accessories, so that transformers can effectively resist lightning surges and ensure stable power supply throughout the year across Indonesia.