Engineering Quality Assurance Methods

✨ 70% of chip design time goes into Verification. Now imagine AI cutting that time in half 😀 Working as a Design Verification Engineer at Google, I can clearly see how AI is rapidly reshaping VLSI. What once felt like a distant future is already becoming part of our everyday workflow. Today, the industry already has tools that can: 🔹 Generate RTL code directly from specification documents or architecture diagram. 🔹 Auto-create SystemVerilog/UVM testbenches from high-level inputs 🔹 Use ML to analyze coverage gaps and suggest corner-case tests 🔹 Assist in debugging waveforms and highlight potential root causes 💡 The big shift: Verification engineers will spend less time on repetitive coding and more on guiding AI, validating results, and applying domain expertise. Even in my own work, I don’t remember a single day in last month where I haven’t used some form of AI tools 🧠 Of course, the best AI tool really depends on what you need: some are great for coding, some are best for Circuit diagrams, while a few are better suited for documentation and writing. The key is to mix and match based on your requirement. Beyond popular tools like ChatGPT, Gemini, or Perplexity, here are some AI tools I’ve found particularly useful in Design Verification & VLSI : a) Claude AI – https://claude.ai/new b) Cursor AI – cursor.com/agents c) Bronco AI – https://www.bronco.ai/ 🚀 The pace of change is incredible. AI isn’t just “supporting” verification anymore – it’s starting to reshape how we design and verify chips. 👉 Curious to know in the comments: Which AI tools do you find most effective in your workflow? #VLSI #Semiconductor #Google

𝗬𝗼𝘂𝗿 𝘁𝗲𝘀𝘁 𝘀𝘂𝗶𝘁𝗲 𝗶𝘀 𝗴𝗿𝗲𝗲𝗻. 𝗬𝗼𝘂𝗿 𝘁𝗲𝘀𝘁 𝗱𝗮𝘁𝗮 𝗶𝘀 𝗳𝗶𝗰𝘁𝗶𝗼𝗻. 𝗚𝘂𝗲𝘀𝘀 𝘄𝗵𝗶𝗰𝗵 𝗼𝗻𝗲 𝗽𝗿𝗼𝗱𝘂𝗰𝘁𝗶𝗼𝗻 𝗯𝗲𝗹𝗶𝗲𝘃𝗲𝘀. Most teams I meet can quote their test coverage to two decimals. Very few can tell me where their test data comes from. That gap is expensive. A suite built on stale or invented data reports green while the real edge cases sit waiting in production. You are not testing your software. You are testing a story about your software. I put it bluntly in my book: no test data strategy means flaky tests, late releases, and compliance nightmares. 𝗧𝗵𝗲 𝗽𝗮𝗿𝘁 𝗽𝗲𝗼𝗽𝗹𝗲 𝗺𝗶𝘀𝘀: 𝘁𝗲𝘀𝘁 𝗱𝗮𝘁𝗮 𝗶𝘀 𝗮 𝗳𝗲𝗲𝗱𝗯𝗮𝗰𝗸 𝗹𝗼𝗼𝗽. When the data is wrong, the loop lies to you. Speed on top of a lying feedback loop is not progress, it is risk moving faster. Then AI raises the stakes. The quickest way to leak customer data in 2026 is to hand a production dump to an external model "to help with testing." That one shortcut can breach GDPR, HIPAA, or PCI-DSS in an afternoon. This is why test data management is now a safety layer. Synthetic and masked data lets you run realistic tests, and let AI work on them, without ever exposing a real customer record. Own your data layer, mask it, then let AI in. What good looks like: - Provisioning automated and shifted left into the pipeline, not hand-assembled the night before release - Synthetic and masked data instead of raw production copies - Test data as code, versioned next to the tests it feeds - Self-service, so engineers stop waiting on a DBA None of this is exotic. It is discipline applied to the least glamorous input in engineering, the one that quietly decides whether every test above it is telling the truth. So before you celebrate 90% coverage, ask the harder question: do you trust the data those tests run on, or are you just testing fiction faster? #TestDataManagement #ShiftLeft #ContinuousDelivery #DevOps #DataPrivacy #SoftwareTesting

⚡ 500 kV Current Transformer (CT) Testing & Diagnostic Analysis: Recently, I performed complete diagnostic testing on a 500 kV Current Transformer (CT) to evaluate its accuracy, insulation integrity, and overall performance. CTs play a critical role in protection and metering circuits — ensuring their health is essential for safe and reliable operation of high-voltage systems. 🧪 🧰 Tests Performed & Objectives 🔹 1. Insulation Resistance (IR) Test Purpose: Assess insulation health between primary, secondary, and core. Method: High-voltage DC applied using a Megger Insulation Tester. Interpretation: High IR → Healthy insulation Low IR → Possible moisture or insulation deterioration 🔹 2. CT Analyzer Testing (Megger CT Analyzer) Comprehensive testing performed using Megger CT Analyzer, which automatically measures and analyzes all electrical characteristics of the CT, including: ⚙️ Winding Resistance (WR): Evaluates resistance of secondary windings to detect loose connections or shorted turns. (Measured automatically by CT Analyzer with temperature correction applied.) ⚙️ Ratio Test: Confirms the actual turns ratio matches the nameplate ratio. ⚙️ Phase Error / Phase Displacement: Measures angular deviation between primary and secondary currents — essential for accurate metering and protection. ⚙️ Excitation (Magnetization / Saturation) Curve: Determines the knee-point voltage and CT core behavior under fault conditions. ⚙️ Burden & Accuracy Class Verification: Confirms the CT maintains accuracy under rated burden as per IEC / IEEE standards. ⚙️ Polarity Test: Verifies the correct orientation between primary and secondary terminals. ⚙️ Demagnetization Function: Automatically demagnetizes the CT core after testing to restore accurate characteristics. 🔹 3. Capacitance & Dissipation Factor (C&DF / Tan Delta) Test Purpose: Evaluate insulation dielectric condition and detect early aging. Method: High-voltage AC applied; Capacitance and Tan Delta (Dissipation Factor) measured. Interpretation: ⭐ Stable capacitance → Healthy insulation ⭐ Increased Tan Delta → Possible moisture, heat, or contamination #CurrentTransformer #CTTesting #CTAnalyzer #ElectricalEngineering #PowerEngineering #TanDelta #CapacitanceTesting #DissipationFactor #WindingResistance #InsulationResistance #Megger #HighVoltageTesting #ConditionMonitoring #AGITROLSolutions #Siemens #TestingAndCommissioning #ProtectionSystem #ElectricalTesting #IEEEStandards #IECStandards

Failure Analysis | RCA | Fault Diagnosis – 80 MVA, 132/33 kV Power Transformer An 80 MVA, 132/33 kV Power Transformer experienced a severe site failure where the R-phase HV bushing blasted, resulting in the operation of all protection relays. Initial inspection revealed a flashover on the R-phase HV lead. The damaged lead was repaired, and the transformer was successfully re-energized. However, within a few minutes of charging, all three HV bushings catastrophically failed, and the complete protection scheme operated once again. The transformer was declared failed and shifted to the repair bay for detailed investigation. The interesting part began after the transformer reached the factory. All routine low-voltage diagnostic tests—including TTR, winding resistance, IR, magnetic balance, vector group, polarity, and LV short-circuit tests—were found to be within acceptable limits. Even after lifting the Core Coil Assembly (CCA) and applying 15% of rated voltage from the LV side, the transformer behaved normally. The previously flashed HV lead was visible, but there was no electrical indication suggesting an internal winding failure. At this stage, the transformer appeared electrically healthy despite the severe site failure. Instead of relying only on test results, the decision was taken to proceed with complete internal inspection by removing the top yoke. Inspection revealed that all three LV CTC windings had become mechanically disturbed, with multiple locations where the insulation had worn off, leaving the CTC conductors bare. These defects were not detectable through routine electrical tests but became evident only after dismantling. Key Learning This case demonstrates that healthy routine test results do not always guarantee a healthy transformer, especially when CTC LV windings are involved. While CTC windings provide significant advantages such as: ✔ Reduced stray losses ✔ Better current distribution ✔ Improved efficiency they may also be more vulnerable to mechanical displacement under severe short-circuit forces if winding support, clamping, or manufacturing integrity is compromised. Following a high fault current, the winding may suffer mechanical deformation without immediate electrical failure, allowing conventional diagnostic tests to pass while hidden damage remains inside the transformer. Engineering Takeaway Root Cause Analysis should never depend solely on electrical test reports. Combining site observations, relay records, physical inspection, dismantling, and engineering judgement is essential to identify hidden failures that routine diagnostics cannot detect. Sometimes, the transformer passes every test—but the failure is still waiting inside. #PowerTransformer #FailureAnalysis #RootCauseAnalysis #RCA #TransformerFailure #CTCWinding #ElectricalEngineering #HighVoltage #TransformerDiagnostics #ShortCircuitForces #ReliabilityEngineering #EngineeringInsights #TransformerRepair #QualityEngineering

Transformer Testing Used equipment: 1.1 Insulation Resistance Test (Megger Test) • Purpose: Checks insulation health between windings and ground. • Instrument Used: Megger (Insulation Resistance Tester) • Test Voltage: • LV Winding: 500V – 1000V • HV Winding: 2500V – 5000V 1.2 Transformer Turns Ratio (TTR) Test • Purpose: Ensures correct turn ratio between primary and secondary. • Instrument Used: TTR Meter (Transformer Turns Ratio Tester) • Acceptable Range: ±0.5% of design ratio 1.3 Winding Resistance Test • Purpose: Measures resistance of windings to detect loose connections or damage. • Instrument Used: Micro-Ohmmeter / DC Resistance Tester • Test Current: 1A – 10A DC 1.4 Vector Group Test • Purpose: Confirms correct vector group and phase displacement. • Instrument Used: Phase Angle Meter & TTR Meter 1.5 No-Load Loss and Current Test • Purpose: Measures core losses at rated voltage. • Instrument Used: • Power Analyzer • Voltmeter & Ammeter 1.6 Load Loss and Impedance Test • Purpose: Measures copper losses and impedance voltage. • Instrument Used: • Power Analyzer • High-Voltage Source 1.7 Oil Dielectric Strength Test • Purpose: Checks insulation quality of transformer oil. • Instrument Used: BDV (Breakdown Voltage) Tester • Standard Value: Minimum 30 kV for new oil 1.8 Magnetic Balance Test • Purpose: Ensures uniform flux distribution in three-phase transformers. • Instrument Used: Multimeter & Variac (Variable Voltage Supply) 2. Type Tests (Performed on One Unit per Batch) 2.1 Short Circuit Test (Dynamic & Thermal Stability Test) • Purpose: Verifies the transformer’s ability to withstand fault conditions. • Instrument Used: High-Power Short Circuit Test Setup 2.2 Lightning Impulse Test • Purpose: Simulates lightning strikes to check dielectric strength. • Instrument Used: • Impulse Generator • Oscilloscope 2.3 Temperature Rise Test • Purpose: Measures winding and oil temperature rise during full load. • Instrument Used: • Thermocouples • IR Camera 3. Special Tests (As per Customer Request) 3.1 Partial Discharge Test • Purpose: Detects internal insulation defects. • Instrument Used: Partial Discharge Detector 3.2 Sweep Frequency Response Analysis (SFRA) Test • Purpose: Detects winding displacement or mechanical deformation. • Instrument Used: SFRA Analyzer 3.3 Frequency Response Analysis (FRA) Test • Purpose: Checks mechanical integrity of windings. • Instrument Used: Frequency Response Analyzer #power #Transformer #Testing #Maintenance #IFAS #MV

What is RTM and How is Used by Business Analysts? RTM (Requirements Traceability Matrix) is a document that tracks and ensures that all project requirements are properly addressed throughout the project lifecycle. It links requirements to their corresponding test cases, design documents, and deliverables, ensuring complete coverage and reducing the risk of missing critical functionalities. How Business Analysts Use RTM: 1. Tracking Requirements – Ensures all business, functional, and technical requirements are addressed. 2. Validation & Verification – Helps confirm that each requirement is implemented and tested. 3. Change Management – Assists in assessing the impact of changes on existing requirements. 4. Project Transparency – Provides clear visibility to stakeholders on requirement progress and gaps. RTM is crucial in bridging the gap between business needs and project execution, making it a key tool for Business Analysts. #rtm #requirementtraceabilitymatrix #businessanalyst #Bas

Learning – Requirement Traceability Matrix (RTM) in Action As Business Analysts, one of our key responsibilities is to ensure that every requirement defined by stakeholders is delivered, tested, and aligned with business goals. The Requirement Traceability Matrix (RTM) is the tool that helps us achieve this. ⸻ 🔹 What is RTM? RTM is a document (or tool) that creates a map linking: • Business Requirements → Functional Requirements → Design → Test Scenarios/Test Cases → Defects (if any) It acts like a bridge connecting each stage of the SDLC, ensuring nothing falls through the cracks. ⸻ 🔹 How Does It Work? 1. Start with Business Requirements (BRD) or User Stories. 2. Break them down into Functional Requirements (FRD). 3. For each requirement, add the corresponding Test Cases. 4. Update the RTM as development and testing progress. 5. Track the status of each requirement (In-progress, Developed, Tested, Passed/Failed). This creates a one-to-one or one-to-many mapping, showing how each requirement is validated. ⸻ 🔹 Why RTM Helps BAs ✅ Provides end-to-end visibility across the project lifecycle. ✅ Helps in impact analysis – if one requirement changes, you can instantly see which test cases and modules are affected. ✅ Ensures complete coverage – no requirement is left untested. ✅ Reduces miscommunication between Business, Development, and QA teams. ✅ Strengthens UAT (User Acceptance Testing) by providing clear requirement-to-test case links. ⸻ 💡 Live Example: Password Reset Feature • Business Requirement: Users must be able to reset their password if forgotten. • Functional Requirement: A “Forgot Password” link on the login page should send an OTP or reset link to the registered email. RTM Mapping for This Requirement: • Requirement ID: BR-01 • Functional Requirement ID: FR-01 • Test Scenarios: • TS-01: Verify the reset password functionality. • Test Cases: • TC-01: Enter a valid registered email → OTP/reset link should be sent. • TC-02: Enter an unregistered email → Error message should be shown. • TC-03: Reset link expires after 15 minutes. • Defect Mapping (if any): D-001 (Reset link not expiring after 15 mins). This way, if BR-01 changes (e.g., reset by phone number instead of email), the BA can immediately identify which functional requirements, test cases, and defects are impacted. ⸻ 📌 BA Insight: RTM is not just a “QA tool,” it’s a strategic document for BAs. It ensures requirements integrity, gives stakeholders confidence, and makes projects easier to manage — especially in complex systems. #BusinessAnalysis #Requirements #RTM #Testing #LearningJourney

🔹 Transformer Testing – Explanation & Procedure 1.Insulation Resistance (IR) Test Purpose: To check the insulation strength between windings to windings and winding & earth. Ensures no moisture or deterioration. Procedure: Use Megger (500V / 1000V / 2500V / 5000V as per rating). Disconnect all connections from transformer bushings. Apply DC voltage between: * HV ↔ LV * HV ↔ Earth * LV ↔ Earth Record insulation resistance values in MΩ. For better check, also calculate Polarization Index (PI = IR at 10 min / IR at 1 min) 2.Winding Resistance Test Purpose: To measure winding resistance of LV and HV windings. Detects loose connections, shorted turns, or high-resistance joints. Procedure: Use a DC resistance test kit (Micro-ohmmeter) Connect across each winding terminal (HV side & LV side). Pass DC current and measure resistance. Compare with design/previous values; should be balanced across phases. 3.Magnetic Balance Test Purpose: To detect inter-turn short circuits in three-phase transformers. Ensures magnetic circuit balance of windings. Procedure: Apply low voltage AC (around 230V single phase supply) between two phases of HV winding at a time. Measure voltages induced in the third phase. Normal condition → induced voltages follow a definite balanced pattern. Abnormal imbalance → indicates possible winding fault. 4.Vector Group Test Purpose: To confirm the vector group (phase displacement) of transformer windings. Ensures parallel operation compatibility. Procedure: Apply 3-phase supply to HV side. Measure phase-to-phase and phase-to-neutral voltages on HV & LV. Compare phase displacement between HV and LV voltages. Verify with nameplate vector group (e.g., Dyn11, YNd1, etc.). 5.Voltage Ratio Test Purpose: To verify that the ratio of primary to secondary voltages matches the design. Procedure: Apply rated voltage on HV side (or a reduced test voltage). Measure voltage on LV side. Calculate ratio: HV / LV. Compare with nameplate ratio (tolerance ±0.5%). 6.Turns Ratio (TTR) Test Purpose: To accurately check the number of turns ratio between HV and LV. More precise than simple voltage ratio test. PROCEDURE: Use TTR meter(special kit). Connect across HV and LV windings. Inject a low test voltage from TTR kit. Instrument directly displays turns ratio & phase angle error. Compare with rated ratio.

Verification can easily reach 50% of the cost and time of chip design so I am really excited to share our latest chip design breakthrough (led by Steven Herbst). Steven has leveraged his open source Switchboard framework to demonstrate a 1,300X build time spedup and 19X RTL simulation speedup (compared to stock Verilator) for a million core RISC-V based "waferscale" processor! We are proud of this work so we took the time writing up a proper paper and submitted it to a journal (available on arxiv as preprint). The paper goes through the theory and motivation that went into the development of Switchboard. Paper: https://lnkd.in/dCDfS-xQ Switchboard Sources: https://lnkd.in/danEwBMh

Transformers Tests: - 1 - Insulation Resistance Test Used to measure the insulation resistance of the transformer components. Apply HV DC then measure resistance. Indicate the condition of the insulation. 2 - Turns Ratio Test Used to measure the turns ratio of the transformer (Primary and Secondary Windings. Apply voltage on winding then measure the voltage induced in the other winding. Percentage between voltages is the turns ratio of the primary and secondary windings. Accurate test. East to perform. 3 - Winding Resistance Test Used to measure the resistance of the transformer windings (primary and secondary). Done using LV DC source + Multimeter. 4 - Polarity Test Conducted to verify the polarity of the transformer windings. Apply DC source to the primary then measure secondary voltage. Polarity of the windings determined based on the direction of the induced voltage in the secondary winding. Simple and quick. Prevent damage of the transformer during installation. 5 - Open Circuit Test Performed to determine: >No Load Losses. >Magnetizing Current. Keep the secondary open circuited then apply voltage on the primary winding, then measure the primary (current and voltage). Calculate (No-Load Losses & Magnetizing Current). Determine the equivalent circuit then calc Efficiency and Regulation. 6 - Short Circuit Test Performed to determine: >Full Load Current. >Transformer Impedance. Keep the secondary short circuited then apply voltage to the primary winding, then measure the primary (current and voltage). Calculate (Full-Load Current & Impedance). Determine Winding Resistance. Determine Leakage Inductance. 7 - Sweep Frequency Response Analysis (SFRA) Non-destructive test used to detect any changes in the transformer mechanical structure. It can detect Winding Deformation or Shorted-Turns. It makes comprehensive assessment of the transformer condition. 8 - Dissolved Gas Analysis Test (DGA) Used to detect the presence of combustible gases in the transformer oil. Analyze a sample of the transformer oil to detect any changes in the gas concentration. It can detect incipient faults before they become major problems which allows predictive maintenance 9 - Partial Discharge Test Used to detect any partial discharges occurring within the transformer insulation. Apply HV to the transformer, then measure any partial discharge in the insulation. Can detect insulation faults before they cause significant issues to the transformer. 10 - Dielectric Withstand Test Apply HV to the transformer to test the ability of the insulation to withstand any voltage stress. Detect insulation weakness and that enables us to ensure the safety and reliability of the transformer. 11 - Thermal Imaging Test Uses infrared imaging to detect hot spots or temp gradients. It can detect problems such as: >Loose Connections. >Overload Components. It provides a non-invasive assessment of the transformer condition.