Load Tap Changers (LTCs) are critical components in power transformers, regulating voltage and maintaining system stability under varying load conditions. But because LTCs switch under load, they are also one of the most maintenance-intensive and failure-prone components in the transformer system.
When an LTC fails, the results can include extended outages, costly repairs, and even collateral transformer damage. That’s why Condition-Based Maintenance (CBM), supported by specialized diagnostics, is essential.
At TJ|H2b Analytical Services, our Tap Changer Activity Signature Analysis, TASA®, is a proprietary diagnostic program designed to deliver precise, actionable insight into tap changer condition.
Rather than relying solely on time-based or reactive maintenance, TASA® enables utilities and industrial operators to monitor oil condition, assess contact wear, and plan maintenance based on true equipment health.
What Is TASA® Diagnostic Testing & What Does It Cover?
With over 25 years of expertise, TJ|H2b is a pioneer in condition-based maintenance (CBM) programs for high-voltage power equipment.
Our Tap Changer Activity Signature Analysis (TASA®) service integrates multiple test methods and advanced interpretation to give a comprehensive evaluation of load tap changer performance and degradation.
1. Comprehensive Test Suite
TASA® combines several diagnostic parameters that together provide a complete condition assessment:
- Dissolved Gas Analysis (DGA): Detects gases generated by arcing, overheating, and partial discharge within the LTC.
- Insulating Fluid Quality Assessment: Evaluates moisture content, acidity, dielectric strength, and overall condition to monitor fluid integrity.
- Particle Analysis: Identifies contamination levels which can indicate mechanical wear, contact erosion, or rust formation.
- Diagnostic Evaluation: Integrates fluid and gas results with equipment and maintenance specifics to determine LTC health and maintenance needs.
This combination goes beyond simple gas limits, providing true activity signatures that characterize the mechanical and electrical performance of the tap changer.
2. Why LTCs Need Specialized Analysis
Traditional DGA methods were first developed for transformers, but LTCs behave very differently.
Gas production in tap changers is more complex, often influenced by design, load operation, ventilation, and filtration.
Because gases may vent or be generated even during normal switching, gas thresholds alone are insufficient for accurate evaluation.
That challenge led to the creation of TASA®, which interprets gas patterns in conjunction with particle, fluid, equipment, and maintenance data, giving a complete picture of LTC load path component health.
3. Reducing Maintenance Costs & Preventing Failures
Performing full internal LTC maintenance can take significant time and cost.
With TASA®, operators can identify:
- Units requiring immediate maintenance due to deterioration or contamination.
- Units operating normally that do not yet need service.
This data-driven approach allows maintenance to be focused where it’s truly needed, reducing unnecessary overhauls, avoiding collateral transformer damage, and optimizing resource allocation.
4. Supporting Equipment Reliability Throughout the Lifecycle
TASA® delivers diagnostic value from commissioning through long-term operation:
- Baseline Testing: Establishes initial condition and fluid quality.
- Routine Trending: Detects evolving contact wear, fluid degradation, and contamination.
- Predictive Maintenance: Enables proactive parts planning and minimizes unexpected downtime.
By trending TASA® results over time, operators can transition from fixed-schedule maintenance to true CBM, improving reliability and cost efficiency.
5. Independent, Purely Diagnostic Testing
TJ|H2b is purely diagnostic.
We don’t perform maintenance or repair work, ensuring unbiased testing, honest interpretation, and trusted recommendations.
With 11 laboratory locations worldwide, TJ|H2b provides rapid analysis, consistent methodology, and expert consultation across all service regions.
Benefits of TASA® Diagnostic Testing
- Identifies which LTCs require maintenance and which do not.
- Reduces failures and prevents collateral transformer damage.
- Optimizes maintenance resources and planning schedules.
- Improves safety and operational reliability.
- Supports asset management decisions with data-driven clarity.
Getting the Most from Tap Changer Activity Signature Analysis®
With TASA® Diagnostic Testing, utilities and asset managers gain the insight needed to protect these components through data-driven, condition-based maintenance.
At TJ|H2b Analytical Services, our mission is to empower clients with accurate, independent diagnostics that improve reliability, lower maintenance costs, and prevent failures before they occur.
Enhance LTC reliability with confidence. Contact TJ|H2b today to learn more about TASA® diagnostic testing.
FAQs on Diagnostic Testing
Q1. How often should a tap changer be analyzed?
After performing a TASA® analysis, each tap changer receives a condition rating. The recommended sampling interval ranges from immediately to annually, depending on the equipment’s health.
Q2. What does the condition code mean?
The condition code reflects the LTC’s relative health — from normal operation to critical fault conditions — and guides next steps for maintenance or resampling.
Q3. Can TASA® detect issues before a failure occurs?
Yes. TASA® identifies early-stage contact wear, insulation charring, and contamination long before operational issues appear.
Q4. What parameters does TASA® evaluate that other tests miss?
Unlike basic oil analysis, TASA® examines gas activity patterns, particle contamination, and fluid degradation together.
Q5. Is TASA® cost-effective compared to routine LTC maintenance?
Absolutely. By isolating which units truly need attention, TASA® reduces unnecessary teardown, labor, and downtime while preventing high-cost failures.
