Principales elementos de prueba (funciones básicas)
A
1.Winding DC Resistance Test:Purpose: To check the quality of winding connections, the contact integrity of tap changers, and for possible shorted turns.Principle: Applies a direct current and measures the resistance.
2. Prueba de relación de transformación y grupo vectorial:
Purpose: To verify the voltage transformation ratio matches the design specifications, check the correctness of the winding turns ratio, and determine the transformer’s connection vector group (e.g., Dyn11, Yyn0).Principle: Measures the voltages on the high-voltage and low-voltage sides simultaneously to calculate the ratio and phase difference.3. Prueba de resistencia de aislamiento (relación de absorción, índice de polarización):
Purpose: To evaluate the dryness and overall condition of the transformer’s complete insulation system.Principle: Applies a high DC voltage and measures the leakage current flowing through the insulation to calculate the resistance.4. Prueba del factor de pérdida dieléctrica (tan δ):
Purpose: A sensitive indicator to determine if the transformer’s insulation (mainly oil-paper insulation) is damp, aged, or deteriorated.Principle: Measures the ratio of power lost in the insulating material under an AC electric field.5. Prueba de pérdidas en vacío y corriente en vacío:
Purpose: To measure the magnetic performance and core loss (iron loss) of the transformer core, checking for defects in the core material, design, or manufacturing.Principle: One winding is left open, and the rated voltage is applied to the other winding; the losses and current are measured.6. Prueba de pérdidas en carga y tensión de impedancia (prueba en cortocircuito):
Purpose: To measure the copper losses in the windings, calculate the transformer’s operating efficiency and temperature rise, and obtain the crucial impedance voltage parameter.Principle: One winding is short-circuited, and a current is applied to the other winding to bring it to rated current; the losses and voltage are measured.7. Ensayo de tensión soportada a frecuencia de potencia (ensayo de tensión aplicada):
Purpose: To assess the strength of the transformer’s main insulation and verify its ability to withstand overvoltages in operation.Principle: Applies an AC power frequency voltage significantly higher than the rated voltage for a specified duration to check if the insulation breaks down.8. Ensayo de tensión inducida de soporte (ensayo del aislamiento entre espiras y entre capas):
Purpose: To assess the strength of the transformer’s longitudinal insulation (insulation between turns, layers, and sections).Principle: Applies a voltage at a frequency higher than twice the rated frequency to induce a test voltage that is a multiple of the rated voltage.9. Prueba de descarga parcial:
Purpose: To detect the presence of partial discharges within the transformer, which is a critical sign of early-stage insulation deterioration.Principle: Uses high-frequency sensors to detect tiny discharge signals within the insulation.