Evaluating Transformer Health in Pakistan: Techniques & Strategies by SGS

Transformers are indispensable in power systems, representing a significant investment and requiring diligent care throughout their lifecycle. These critical components face various integrity challenges, from manufacturing to operation. Undetected issues can lead to catastrophic failures, underscoring the importance of routine and preventive maintenance. 

Delivering excellence in transformer testing

SGS, a leader in testing and inspection services, offers advanced transformer testing solutions to predict, detect, and mitigate potential failures. By leveraging IEEE and ASTM standards, SGS ensures transformers operate reliably and efficiently. 

Key testing practices and their benefits 

Periodic General Inspections 

Routine visual and operational inspections provide insights into a transformer’s condition, enabling early detection of wear, leaks, or malfunctioning components. Regular inspections reduce the risk of sudden outages and ensure equipment longevity.

Insulating Liquid Testing

The insulating liquid serves as both an insulator and a cooling medium in transformers. SGS uses industry-standard tests to evaluate its condition:

• Acid Number Test (ASTM D974): Determines the acidity of the insulating fluid. A high acid number indicates oil degradation and potential insulation system damage
• Dielectric Breakdown Voltage Test: Assesses the fluid's ability to withstand electrical stress without breakdown. Low values suggest contamination or moisture presence
• Dissolved Gas Analysis (DGA): Identifies gases dissolved in transformer oil, which are byproducts of thermal or electrical stresses. Early detection of key gases like hydrogen or ethylene can indicate overheating, arcing, or insulation failure
• Sludge Test: Evaluates sludge levels, which can reduce cooling efficiency and impede transformer performance

Transformer Winding Assessments

Winding integrity is vital for transformer performance. Winding condition can be assessed through: 

• Insulation Resistance Test: Checks for low-resistance paths that could result from deteriorating insulation
• Winding Resistance Measurement: Identifies issues such as broken conductors, loose connections, or shorted turns, which could lead to inefficiencies or faults
• Capacitance and Dissipation Factor (Tan Delta) Test: Analyzes the ratio of resistive to capacitive leakage current, providing insights into insulation aging or contamination
• Transformer Turns Ratio (TTR) Test: Verifies the ratio between primary and secondary windings, ensuring the transformer delivers the expected voltage levels
• Excitation Current Test: Measures the current required to energize the core under no-load conditions. Abnormal readings may indicate core defects or winding short circuits
• Short Circuit Impedance Test: Detects changes in impedance caused by mechanical shifts or winding deformation during service

Advanced Diagnostics

Advance diagnostics are deployed to evaluate internal structural and electrical integrity of the transformers. These included: 

• Sweep Frequency Response Analysis (SFRA): Evaluates the structural and electrical integrity by comparing frequency response patterns. Deviations from baseline data may indicate core or winding displacement
• Dielectric Response Analysis (DIRANA): Assesses insulation moisture content and aging through polarization and depolarization currents, providing detailed diagnostics of both oil and paper insulation systems

Our value addition 

• Comprehensive Diagnostics: SGS provides an end-to-end assessment of transformer health, ensuring all potential risks are identified
• Proactive Maintenance Solutions: Early detection minimizes downtime, prevents unexpected failures, and extends equipment lifespan
• Industry Expertise: SGS adheres to international standards like IEEE and ASTM, ensuring reliability and accuracy in every test. We have proven experience and track record, having tested the biggest Power transformer (825MVA) in Pakistan

Conclusion 

Transformers are vital to power systems, demanding proactive maintenance to ensure reliability and prevent failures. SGS’s specialized testing techniques provide valuable insights, safeguarding investments and enhancing performance. By integrating these practices into maintenance routines, operators can ensure long-term stability and operational efficiency of their power networks.