Views: 0 Author: Site Editor Publish Time: 2025-03-31 Origin: Site
Transformers, as the core equipment in power systems, perform critical functions including voltage transformation, current regulation, and electrical isolation. Their stable operation is paramount to ensuring the safety and efficiency of electrical networks. The following sections provide a detailed analysis of transformer operation management, common fault detection methodologies, and troubleshooting procedures.
Prior to commissioning a transformer, a comprehensive inspection must be conducted to verify its readiness for optimal operation:
Fastener and Connection Inspection: Conduct a thorough examination of all fasteners inside and outside the transformer, particularly at critical connection points such as wiring terminals and busbars. Ensure proper torque application during tightening to prevent thread damage, while avoiding seizing caused by material incompatibility between bolts and nuts.
Component Installation Verification: Validate the proper reinstallation of all components disassembled during transportation or installation, inspect internal cooling ducts for debris-free conditions, and confirm the absence of residual tools within the transformer enclosure.
Temperature Control Device Inspection: Verify that control cables for temperature controllers and indicators are routed away from coil surfaces and live parts. Re-secure as needed to prevent interference.
Cooling System and Auxiliary Equipment Inspection: Verify proper operation of cooling fans, temperature control devices, and ancillary systems. Specifically confirm the fan rotation direction to ensure airflow is directed upward from the base of the transformer windings.
To validate compliance with design specifications, the following mandatory tests shall be performed prior to transformer commissioning:
DC Resistance Measurement: Conduct winding resistance measurements across all tap positions to verify compliance with design specifications.
Voltage Ratio Measurement: Verify the accuracy of voltage transformation ratios and confirm the correctness of vector group designation through polarity and phase sequence checks.
Insulation Resistance Test: Perform dielectric testing between the core and clamping structures to verify insulation integrity.
Winding Insulation Resistance Test: Measure the insulation resistance of windings to verify electrical safety compliance.
Power Frequency Withstand Test: For field-repaired transformers returning to service, the dielectric withstand voltage test shall be conducted at 80% of the original factory test voltage level, in accordance with IEC 60076-3 Clause 10 requirements.
Grounding System Inspection: Conduct rigorous inspection of the grounding system post-installation to verify its secure and reliable operation.
Safety Barriers: Transformers lacking enclosure protection shall be equipped with isolation barriers to prevent direct contact with live parts and mitigate electrocution risks.
Operation by Qualified Personnel: Installation, commissioning, and maintenance of transformers shall be conducted exclusively by certified professionals to ensure compliance with operational standards and safety protocols.
Temperature Control System Activation: Prior to energization, calibrate and test the temperature controller or temperature display unit to verify proper operation.
Energization Procedure: Close the circuit breakers with the transformer in no-load condition. Activate instantaneous overcurrent protection relay during energization to mitigate inrush current effects.
Gradual increase in load: After being put into operation, the load should be gradually increased and monitored for any abnormal sounds or vibrations to avoid sudden increases in load.
Moisture Mitigation Protocol: For de-energized transformers exposed to ambient humidity >80% RH.
Overheating fault: This includes localized overheating and excessive overall temperature rise. Inspect load, current, and heat dissipation conditions.
Discharge faults: May manifest as partial discharge, arc discharge, or spark discharge; typically associated with insulation issues.
Insulation fault: Such as insulation breakdown or degradation of insulation performance; damaged insulating materials must be promptly inspected and replaced.
Other faults: Including abnormal noise, protection malfunction, oil leakage, etc.
Visual inspection: Check load current, oil color changes, and external appearance for abnormalities (e.g., oil leakage, discoloration) .
Auditory monitoring: Listen for abnormal noises during operation (e.g., uneven buzzing, crackling, or hissing sounds).
Electrical measurement: Measure three-phase DC resistance and insulation resistance to assess whether values fall within the normal range.
The decrease in insulation performance is a common fault of transformers, especially in humid environments. The insulation resistance test should be conducted under suitable conditions, with the following standard values:
HV to LV and ground: ≥ 300 M Ω (10kV), ≥ 1000 M Ω (35kV).
HV to ground: ≥100 MΩ.
For core/accessories to ground, refer to manufacturer documentation.
If a transformer exhibits moisture ingress or condensation (e.g., visible droplets on epoxy resin surfaces or core components), immediate drying is required to restore insulation integrity, regardless of its current insulation resistance value.
The normal operation of a transformer will produce a buzzing sound that varies with the load. If there is an abnormal sound, further analysis is needed:
Core loosening: Produces clanking or whirring noises due to unsecured laminations or insufficient bolt torque.
Ungrounded core: Generates snapping discharge sounds from electrostatic buildup between core and tank.
Switch contact defects: Causes squeaking or crackling from arcing in tap changers or busbar joints.
Lead/winding discharge: Emits popping audible arcs from insulation breakdown in high-voltage regions.
Contaminated bushings: Triggers hissing corona discharge due to surface oil/particle accumulation.
Failure to Power On: Check the power supply, fuses, terminal connections, and switch status.
No Temperature Display: Check the sensor connection and resistance.
Temperature Deviation: Check the installation of sensors and interference sources.
Communication Failure: Check the communication line and contact the supplier's technical support.
Three phase voltage imbalance is often caused by grounding faults or load imbalance. The solutions include:
Multipoint Grounding for Neutral Line Loss Reduction：Implement multipoint grounding in low-voltage distribution networks to reduce neutral line power losses by optimizing current return paths and minimizing impedance.
Single-Phase Transformer Deployment：Utilize single-phase transformers for areas with dominant single-phase loads (e.g., residential zones) to isolate unbalanced currents and prevent harmonic interference.
Load Monitoring & Balancing: Conduct periodic load measurements using clamp meters to quantify current deviations between phases.
Oil Darkening: Darkening of oil (e.g., amber turn into brown/black) indicates moisture absorption and oxidation degradation, leading to reduced dielectric strength and increased acidity. Replace degraded oil promptly to prevent accelerated insulation aging and potential equipment failure.
Oil Leakage: Determine whether to continue operating and arrange maintenance based on the oil leakage situation, or immediately shut down and replenish oil.
In conclusion，Stable operation of transformers is the cornerstone of power system reliability. Through meticulous inspections, prompt fault diagnosis/resolution, and proactive maintenance, the service life of transformers can be effectively extended, failure rates minimized, and the safety/efficiency of power systems ensured.
