Ensuring accuracy and repeatability in transformer manufacturing is critical, not only for product quality, but also for long-term performance and reliability in the field.

The team at Asya Trafo, a leading transformer test equipment manufacturer, faced a familiar challenge: how to improve oil filling precision and mechanical fatigue testing consistency while reducing maintenance and operational disruptions.

Their experience highlights how advanced measurement technologies, specifically Coriolis mass flow meters, can significantly improve process reliability in demanding testing applications.

The Challenge: Measurement Limitations Impacting Testing Reliability

Transformer oil plays a critical role in both insulation and cooling, making accurate oil filling essential. At Asya Trafo, oil was measured and delivered during vacuum filling and fatigue testing processes that simulate thermal expansion and contraction cycles.

However, the existing system based on gear flowmeters introduced several challenges:

• • Measurement accuracy limited to approximately ±2–2.5%
  • Frequent maintenance due to particle-sensitive mechanical components
  • Filter replacements required before nearly every test cycle
  • Air entrainment causing unstable readings
  • Temperature-driven volumetric inconsistencies affecting repeatability

These issues not only impacted oil filling precision but also reduced confidence in fatigue test results and increased downtime.

Why Mass Measurement Matters in Transformer Applications

Unlike volumetric measurement technologies, Coriolis flow meters directly measure mass rather than volume. This distinction is critical in transformer oil applications, where oil is bought, sold, and specified in mass units (kilograms).

Additionally, volumetric measurement methods can be influenced by temperature changes introducing variability into both filling operations and test simulations.

For processes that require consistent, repeatable performance, such as fatigue testing, measurement stability is essential.

The Solution: Coriolis Measurement for Accuracy and Reliability

To address these challenges, Asya Trafo implemented Micro Motion™ G-Series Coriolis Mass Flow & Density Meters to measure and control transformer oil with greater precision.

Several capabilities made this technology particularly effective:

• • Direct mass flow measurement, eliminating dependence on temperature or density
  • No moving parts, reducing maintenance requirements and eliminating failure points
  • Integrated temperature measurement, without impacting accuracy
  • Entrained air detection, improving process visibility and stability
  • Flexible installation, with minimal straight pipe requirements

These features allowed the system to maintain consistent oil delivery and provide accurate feedback during dynamic fatigue testing conditions.

The Results: Improved Accuracy and Repeatability

By switching to Coriolis-based measurement, Asya Trafo achieved measurable improvements in both oil filling and fatigue testing performance:

• • Up to 5x improvement in measurement uncertainty (from approximately ±2.5% to ±0.5%)
  • Ability to perform up to 2,000 repeatable fatigue test cycles without temperature influence
  • Elimination of frequent filter replacements, reducing maintenance interventions
  • Improved test consistency through real-time detection of entrained air

These gains translated into more reliable testing, improved process confidence, and reduced operational disruption.

Supporting Reliable Transformer Testing and Quality Assurance

Accurate simulation of transformer operating conditions is essential for product validation. By enabling precise control of oil mass during injection and retraction, Coriolis technology helps replicate thermal cycling behavior more consistently.

This not only improves testing reliability but also supports broader quality assurance goals across transformer manufacturing operations.

In addition, reduced maintenance requirements and enhanced diagnostics simplify system operation and improve overall efficiency.

Key Takeaways for Measurement and Testing Applications

For engineers and operators working with transformer oil systems, or similar fluid processes, this example highlights several important considerations:

• • Mass measurement provides greater accuracy and stability than volumetric methods
  • Eliminating mechanical components reduces maintenance and downtime
  • Real-time diagnostics improve process control and troubleshooting
  • Measurement reliability directly impacts product quality and test confidence

Read the full case study here. For more information on Emerson solutions for the Power & Energy industry, visit our Measurement Instrumentation for Power page at Emerson.com.