The International Electrotechnical Commission standard IEC 61869-3 establishes global specifications for inductive voltage transformers used in electrical measurement and protection systems.
When specifying potential transformers for international utility projects, engineering firms must pay close attention to three core parameters:
1. Rated Burden & Accuracy Class: Burden represents the total apparent power (VA) connected to the secondary winding. Operating a Class 0.2 PT outside its specified burden window (e.g. 25% to 100% of rated VA) will cause ratio error drift beyond class limits.
2. Voltage Factor (Vf) & Duration: For effectively grounded systems, the voltage factor is typically 1.2 continuous and 1.5 for 30 seconds. For ungrounded or resonant grounded networks, a voltage factor of 1.9 Un for 8 hours is required to survive ground faults.
3. Partial Discharge (PD) Testing: PD in cast resin or paper-oil insulation indicates microscopic void formation. PotentialTransformers.com tests 100% of production units in our high-voltage Faraday cage, guaranteeing PD < 5pC at 1.2 Un.
By selecting KEMA-certified PTs manufactured under IEC 61869-3 guidelines, utility operators ensure reliable revenue billing and protection relay performance for decades.