The standard refines the calculation of minimum air clearances. It emphasizes the relationship between the Rated Lightning Impulse Withstand Voltage (LIWV) and the Rated Power Frequency Withstand Voltage. The 2021 edition provides updated tables for phase-to-earth, phase-to-phase, and phase-to-structure clearances, ensuring designs can withstand transient overvoltages more effectively.
The operator must maintain an “Installation File” including single-line diagrams, earthing plans, coordination curves, and inspection logs for the entire 40-year lifecycle.
General design requirements
Insulation coordination and overvoltages
Earthing (grounding) and equipotential bonding iec 6193612021 link
Protection against electric shock
Short-circuit and fault studies
Overcurrent protection and coordination
Switching, control and protection devices The standard refines the calculation of minimum air
Cables and conductors
Busbars, busducts and switchgear
Indoor and outdoor installation specifics
Testing, commissioning and maintenance
Documentation
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IEC 61936-1:2021 works in close conjunction with IEC 61936-2 for earthing. The standard reinforces the requirement for Earth Potential Rise (EPR) calculations. It specifies that earthing systems must limit touch and step voltages to safe levels, explicitly accounting for fault currents from modern inverter-based resources (like solar and wind farms), which can have different fault characteristics than traditional rotating machines.
The standard mandates a multi-layered approach to safety: General design requirements
For installations using oil-filled transformers and reactors, IEC 61936-1:2021 dictates: