Power Transformer Failures - Causes, Protection Strategies, and Technological Solutions

The Cost of Transformer Failures -

    In India, power transformers are a critical infrastructure in the transmission and distribution system. Despite their robust design, hundreds of transformers fail or catch fire each year, resulting in -

• Energy loss
• Grid instability
• Downtime of feeders and substations
• Massive financial losses for DISCOMs (distribution companies)

Power Transformer Protection

    According to industry data, transformer failures cost Indian DISCOMs hundreds of crores annually, including replacement cost, service interruption, penalties, and manpower.

Causes of Transformer Failure -

1. Overloading - Transformers exceeding 80–85% loading over extended periods cause insulation deterioration.

2. Poor maintenance and oil contamination - Moisture and impurities in transformer oil reduce dielectric strength.

3. Short circuits or transient faults. 

4. Lack of protection relays or faulty relay settings.

5. High ambient temperature and inadequate cooling.

6. Lightning surges or switching overvoltages.

7. Ageing and mechanical vibration.

8. Fire risks stemming from oil leaks and combustible environments.

Technical Methods to Prevent Transformer Failure -

1. Load Management & Monitoring -

• Install online transformer load monitoring systems using IoT-based current and voltage sensors.
• Implement load shedding algorithms during peak hours or automatic feeder balancing.

Equation for load capacity -

•  S = (√3×V×I) / 1000 (kVA)

Where S = apparent power, V = line voltage, I = current

It should be ensured that the actual S ≤ 80% of - nameplate rating.

2. Online Dissolved Gas Analysis (DGA) -

Use DGA sensors to monitor transformer oil for fault gases like -

• Hydrogen (H₂)
• Acetylene (C₂H₂)
• Methane (CH₄)
• Ethylene (C₂H₄)

    DGA forecasts internal arcing, thermal overload, and insulation degradation prior to failure.

3. Temperature and Thermal Protection -

Install -

• Winding temperature indicators (WTI)
• Top oil temperature sensors
• Digital thermographic scanning during preventive maintenance.

Thresholds -

• Alarm at 80°C
• Trip at 95°C (winding)

4. Protection Relays and SCADA Integration -

• Use Numerical Differential Protection Relays (87T) for internal faults.
• Integrate with SCADA or RTU (Remote Terminal Units) to provide real-time data and alarms.

5. Use of Vacuum or SF₆ Circuit Breakers -

• Replacing oil circuit breakers at substations with vacuum or SF₆ CBs enhances arc quenching and safety.
• Fast-acting breakers prevent faults from propagating and damaging transformers.

6. Routine Testing and Preventive Maintenance -

• IR (Insulation Resistance) Testing
• Tan-Delta and Capacitance Test
• Transformer Turns Ratio (TTR) Test
• Bushing CT and OLTC testing

    Routine preventive schedules reduce the probability of sudden catastrophic failures.

Fire-Fighting Protection Systems for GSS and Transformers

1. Dry-Type and Fire-Retardant Transformers -

    In urban zones, use dry-type cast resin transformers or mineral oil alternatives like FR3 ester-based oils which are -

• Biodegradable
• Non-toxic
• Have high fire point (>300°C)

2. Automatic Fire Detection and Suppression System (AFDSS) -

    Install thermo-sensitive linear heat-sensing cables (LHSC) across GSS transformers and oil tanks. The system includes -

• UV/IR flame detectors
• Nitrogen or clean-agent gas suppression
• Deluge water spray systems for cooling

Smart integration - Link with SCADA or fire panel; trigger alerts and isolate supply instantly.

3. Infrared Imaging and AI Monitoring -

    AI-powered security cameras and infrared sensors identify anomalous heat zones (red-hot) on transformers in real-time. Algorithms predict fire risks using thermal trend analysis.

4. Oil Leakage Detectors -

    Use float-type or capacitive sensors to detect minor oil leakage that may escalate into fire hazards if not addressed.

Financial Savings and Cost-Benefit Analysis for Power Sector Companies- 

Latest Technologies in Transformer Protection

1. Digital Twin Modelling Predictive diagnostics through virtual simulations.
2. IoT-Enabled Smart Transformers with Remote Control.
3. Edge computing-based condition monitoring.
4. AI + ML fault detection algorithms trained on historical failure data.
5. Drone-based thermography for difficult terrains and EHV substations.

What Engineers and Transmissions, and DISCOMs Can Do -

1. Implement failure root cause analysis post every major fault.
2. Train ground staff in oil sampling, relay settings, and fire safety drills.
3. Schedule quarterly thermography and bushing checks.
4. Digitize old substations with sensorized retrofitting.
5. Establish Central Monitoring Centers for transformer health analytics.

        Transformer failures in India can be significantly reduced through proactive technical upgrades, intelligent monitoring, and reliable fire suppression systems. With climate change and increasing electrical loads, electricity companies must modernise transformer protection infrastructure to reduce financial losses, increase grid reliability, and ensure public safety.

Power Factor Explained

Power Factor (PF) is the ratio of real power (P, in kilowatts, kW) used by a load to do useful work to the apparent power (S, in kilovolt-amperes, kVA) drawn from the grid.

  PF = P/S = cos φ = Active Power / Apparant Power

- φ = the phase angle between the waveforms of voltage and current.

• Real power (P) does the work (lighting, heating).
• Reactive Power (Q) (in kVAR) oscillates between source and load, creating magnetic fields (motors, transformers).
• Apparent Power (S) combines both - S² = P² + Q².

Layman’s Analogy - 

Imagine water flowing through a hose - 

• Real power is like the water you actually use (to water plants).
• Reactive power is when water flows back and forth in the hose without actually watering anything (only creating pressure).
• All of the water in the hose, both wasted and helpful, is known as apparent power.
• A good PF (near 1) means almost all water goes to your plants.
• A poor PF (low) means lots of water just sloshes and doesn’t water.

What Happens with Good v/s Poor Power Factor?

What can be done for Power Factor Improvement- 

• Use PF Correction Devices - Capacitor banks or smart PF controllers.
• Choose PF‑Certified Appliances - Look for motors and appliances with PF > 0.9.
• Regular Maintenance - Keep motors and compressors clean for optimal magnetics.
• Balance Loads Across Phases - (in three‑phase systems) to avoid neutral overloading.

- GGJ

Comparison between Dry-type copper wound and Dry-type aluminum wound Transformers

Dry Type Transformer

Dry-Type Copper Wound Transformer - A dry-type copper wound transformer is a transformer that uses copper conductors in its windings and relies on air or resin insulation instead of oil for cooling. Known for their high electrical conductivity, durability, and efficiency, these transformers are ideal for critical and long-term installations where performance and reliability are key.

Dry-Type Aluminum Wound Transformer - A dry-type aluminum wound transformer uses aluminum conductors in the windings and is similarly air- or resin-insulated, eliminating the need for oil. These transformers are lighter and more cost-effective, making them suitable for installations where budget and ease of handling are more important than maximum efficiency.

1. Conductor Material 

Copper

• Higher electrical conductivity (\~59.6 MS/m)
• Requires a smaller conductor cross-section

Aluminum -

•  Lower conductivity (\~36 MS/m)
•  Requires a larger conductor size for the same current

Best - Copper

2. Resistance

Copper -

•  Lower electrical resistance
•  Reduces I²R losses

Aluminum -

• Higher resistance
• More heat and power loss

Best - Copper

3. Heating & Thermal Performance -

Copper-

• Better heat dissipation
• Lower temperature rise
• Less thermal expansion

Aluminum -

• Heats up more
• Higher thermal expansion (can cause joint issues)

Best - Copper

4. Efficiency -

Copper -

• Higher energy efficiency
• Better for long-term power savings

Aluminum - 

• Slightly lower efficiency

Best - Copper

5. Losses - 

Copper -

• Lower copper (I²R) losses

Aluminum - 

• Higher copper losses

Best - Copper

6. Size and Weight - 

Copper - 

• Compact winding size
• Heavier due to high density

Aluminum - 

• Larger windings
• Lighter and easier to handle

Best - Aluminium (for weight-sensitive setups)

7. Life Expectancy - 

Copper - 

• Longer lifespan
• Stronger mechanical strength
• Less prone to oxidation

Aluminum - 

• Shorter lifespan
• Higher risk of connection issues over time

Best - Copper

8. Oil & Insulation (Dry-Type Specific)-

Both - Use air or resin for cooling, no oil required, environmentally friendly

Best - Equal

9. Indoor/Outdoor Suitability - 

Copper - 

• Excellent in harsh outdoor environments

Aluminum - 

• Acceptable, but more prone to corrosion

Best - Copper

10. Mechanical Strength & Reliability -

Copper -

• Stronger
• Withstands vibrations and short-circuits better

Aluminum - 

• Softer metal
• Lower mechanical endurance

Best - Copper

11. Cost Consideration

Copper - 

• Higher initial cost
• Lower lifetime cost due to durability and efficiency

Aluminum - 

• Lower initial cost
• Higher total cost due to greater losses

Best - Aluminium (when budget is a constraint)

12. Installation & Handling - 

Copper -

• Heavier and harder to move/install

Aluminum - 

• Facilitated transportation and installation owing to reduced weight

Best - Aluminum

13. Accuracy (Voltage Regulation)-

Copper -

• Lower voltage drop
• Tighter voltage regulation

Aluminum - 

• Higher voltage drop under load

Best - Copper

So, lets check in below-

Factors                   /                         Suitable

..................................................................................................................................

In Efficiency                             -           Copper        

Mechanical Strength & Life  -           Copper        

Heating & Thermal Stability -          Copper       

Price                                           -          Aluminum

Weight & Portability               -          Aluminum

Durability outdoors                 -         Copper  

Handling & Transport             -         Aluminum

Final Recommendation - 

• Choose a copper-wound transformer for high efficiency, long life, critical loads, and reliable performance.
• Choose an aluminum-wound transformer for budget-conscious applications, lighter installations, or temporary use.

- GGJ

Impact on electrical system if the Transformer is given 100 % Solar Load

    

The electrical system on the solar load

 Let us consider the case first - 

    I have a 100 KVA distribution transformer installed near my house (considering PF 0.9). The total solar load applied by households in that area is 90 kW, which will be fed through this 100 kva transformer. The parameters are -

1. Transformer rating = 100 kVA  
2. Power Factor = 0.9 (lagging, assumed typical for residential loads)  
3. Rated real power = 100 × 0.9 = 90 kW
4. Total solar load on system= 90 kW

    As per the condition, let's say all 90 kW solar generation is connected to feed into the transformer (i.e., export to the grid or supply local loads).

What Happens Technically When 90 kW Solar Is Connected?

1. Loading of Transformer - The transformer is rated 90 kW at PF 0.9. If all 90 kW solar starts generating at peak - 

1.  The transformer is operating at full real power capacity.
2.  But in real life, transformers also handle reactive power (kVARs), so apparent power can exceed 100 kva.

Risk Involved - If the local load is low (at night or on holidays), this full 90 kW might be pushed back to the grid, causing reverse power flow.

2. Reverse Power Flow - Transformers are usually not designed for continuous reverse flow unless specially specified.

- If generation > local consumption, surplus power flows back from LV to HV side, i.e., from 415 V to 11 kv in India.

Impacts -

• Overheating of the transformer due to reverse magnetisation.
• Protection malfunctions (relay settings typically designed for forward load).
• Can lead to overvoltage on the 11 kv feeder, especially if other transformers also have high solar.
• Utilities may limit solar penetration per transformer (usually 30-50 % of kva capacity); however, in JdVVNL, AVVNL, JVVNL, Rajasthan  norms its 80 % of the Transformer capacity.) 

3. Voltage Rise on LT Side -

• The LT line's voltage increases as a result of solar power.
• With 90 kW connected and minimal local consumption:
• LT voltage can exceed permissible limits (say > 240 V phase-to-neutral).
• May trip inverters due to overvoltage (anti-islanding protection).
• Uneven PV output can cause voltage fluctuations, especially if single-phase inverters are used.

4. Thermal Overload Risk -

• The transformer is designed for typical residential loads, with diversity and non-peak coinciding.
• 90 kW solar = non-coincident, simultaneous injection → actual load on transformer may exceed thermal limit.
• Temperature rise in windings, insulation degradation → shortens transformer life.

5. Power Quality Issues -

• If many inverters operate simultaneously - 
• It may introduce harmonics and voltage flicker.
• Also results in unbalanced loads (if solar is not equally spread across 3 phases), neutral heating, and voltage imbalance.

Solutions & Measures -

1. Limit Solar Capacity on DT -

• Follow solar hosting capacity guidelines and respective acts and norms to be followed with discipline. 
• Generally, max 30–50% of transformer capacity or as applicable by various discom norms of different states.
• For 100 kVA DT → limit solar to 30–50 kW (or as decided by the distribution company norms across states).

2. Upgrade Transformer -

- If demand justifies -

•  Upgrade to a 100 kVA or 160 kVA transformer.
•  Ensure it supports bi-directional power flow.

3. Install LT Side Voltage Regulation -

• Use on-load tap changers (OLTC) or line voltage regulators.
• Monitor and stabilise the voltage rise due to solar.

4. Install Reverse Power Relays or Limiters -

• Prevent dangerous export by tripping or curtailing excess generation.
• Or install net metering + export limiters.

5. Phase Balancing -

• Ensure solar connections are equally distributed across the 3 phases.
• Prevents overloading of a single phase and neutral heating.

6. Real-time Monitoring System -

IoT or SCADA monitoring of ----

•  Transformer loading
•  Voltage at the LT side
•  Solar injection
•  Reverse power

7. Energy Storage (Optional but Effective) -

• Use battery storage to store excess daytime generation.
• Reduces grid injection and stabilises voltage.

Types of Solar Rooftop Plates - Working, Specifications, Capacity & Lifespan

        With the rise in demand for renewable energy, solar rooftop systems have become a widely adopted solution for both residential and institutional electricity needs. At the core of these systems are solar plates—commonly known as solar panels—which convert sunlight into electricity. The selection of the right solar panel type depends on efficiency, installation area, budget, and desired output.

Solar Rooftop Plates - Working, Specifications, Capacity & Lifespan

Working Principle of Solar Rooftop Plates -

    All solar panels work on the photovoltaic effect. When sunlight hits the surface of a solar cell, photons in the sunlight dislodge electrons in the silicon-based semiconductor material. These free electrons flow through an electric circuit, generating direct current (DC), which is later converted into alternating current (AC) via an inverter for use in homes or institutions.

Types of Solar Rooftop Panels (Plates)

1. Monocrystalline Solar Panels (Mono-Si)

Made from a single crystal structure of high-purity silicon, these panels are known for their sleek black appearance and high efficiency.

- Efficiency - 18% to 22%

- Temperature Coefficient - 0.3% to -0.5% per °C (lower is better)

- Power Output - 320W – 600W (per panel)

- Lifespan - 25–30 years

- Best For - Limited rooftop space, high-efficiency requirements

- Cost - Higher than other types, but provides better ROI over time

Advantages -

- High power output per square meter

- Better performance in low-light and high-heat environments

2. Polycrystalline Solar Panels (Poly-Si)

    These panels are speckled and have a bluish colour because they are made of many silicon pieces that have been melted and put into moulds.

- Efficiency - 15% to 17%

- Temperature Coefficient - ~ -0.4% per °C

- Power Output - 250W – 400W (per panel)

- Lifespan - 20–25 years

- Best For - Larger rooftops, budget-friendly installations

- Cost - Cheaper than monocrystalline

Advantages -

- Cost - effective for large-scale installations

- Stable performance under average sunlight

3. Thin-Film Solar Panels (TFSP) -

    These are made by depositing one or more layers of photovoltaic material on a substrate like glass, plastic, or metal. Amorphous silicon (a-Si) and cadmium telluride (CdTe) are common materials.

- Efficiency: 10% to 12% (can go up to 14% with advanced models)

- Temperature Coefficient - 0.2% to -0.3% per °C

- Power Output - 100W – 300W (per panel)

- Lifespan - 10–20 years

- Best For - Curved or non-traditional roofs, lightweight applications

- Cost - Medium to low

Advantages -

- Flexible and lightweight

- Better performance in shaded or partially sunlit conditions

4. Bifacial Solar Panels -

    These panels can absorb sunlight from both the front and rear surfaces, increasing overall energy yield, especially when installed on reflective surfaces (e.g., white rooftops).

- Efficiency - Up to 25%

- Power Output - 350W – 700W

- Lifespan - 25+ years

- Best For - High-reflectivity rooftops, institutional use

- Cost - Higher initial investment

Advantages -

- Generates more energy from the same area

- Ideal for government or commercial rooftops with higher demands

5. Half-Cut Cell Solar Panels -

    A variation of mono or polycrystalline panels where cells are cut into halves to reduce resistance and improve performance.

- Efficiency - 19% to 23%

- Power Output - 370W – 600W

- Lifespan - 25 years

- Best For - Areas with partial shading or high temperatures

- Cost -Slightly more than standard panels

Advantages -

- Less power loss due to shading

- Higher durability and energy output

Comparison Table -

Panel Type	Efficiency	Lifespan	Power Output	Cost	Best Use Case
Monocrystalline	18–22%	25–30 yrs	320–600W	High	Limited space, max output
Polycrystalline	15–17%	20–25 yrs	250–400W	Medium	Budget-friendly setups
Thin-Film	10–12%	10–20 yrs	100–300W	Low	Lightweight, flexible use
Bifacial	Up to 25%	25+ yrs	350–700W	High	Reflective rooftops
Half-Cut Cell	19–23%	25 yrs	370–600W	Medium	Shaded or hot climates

    Choosing the right type of solar rooftop plate involves understanding your roof’s area, orientation, budget, and power requirement. In Rajasthan’s sun-rich environment, monocrystalline or bifacial panels offer the best long-term value for government and institutional installations, while polycrystalline panels are ideal for cost-sensitive projects.

        Installing efficient solar panels not only lowers electricity bills but also contributes to environmental protection by reducing carbon emissions and promoting clean, renewable energy adoption.

Government Scheme - PM Surya-ghar Muft Bijlee Yojna, an initiative by the central government, aims for the installation of solar net metering for households, under which the government of India offers a subsidy. The scheme to promote renewable energy to cut much higher household bills and helps in the reduction in carbon emission. 

Green Energy - A Sustainable Power Shift for Government Institutions in Rajasthan

Green energy in Rajasthan, solar power for government buildings, renewable energy implementation, sustainable development in Rajasthan, low-cost solar solutions, green energy benefits, solar rooftop in Rajasthan, clean energy in India. 

Green Energy - A Sustainable Power Shift

What Is Green Energy?

Green energy refers to electricity or thermal energy produced from renewable, non-polluting sources like solar, wind, biomass, and hydropower. These sources replenish naturally and emit little to no greenhouse gases, making them ideal for a sustainable energy transition. Unlike fossil fuels, green energy technologies preserve air quality, reduce global warming potential, and support long-term environmental balance.

Technical Overview of Green Energy Solutions - 

1. Solar Photovoltaic (PV) Systems - Direct current (DC) electricity is generated by silicon-based solar panels that capture sunlight. Inverters then transform the DC electricity into alternating current (AC).

2. Wind Turbines - Use the wind’s kinetic force to spin rotors and generate electricity.

3. Biomass Power Units - Convert agricultural or organic waste into energy through combustion or biogas technology.

4. Micro Hydro Systems - These systems leverage flowing water to turn small turbines and produce electricity, and they are suitable for select rural zones.

Rajasthan is particularly well-suited for solar and hybrid energy installations on public sector buildings because of its large open terrain and high solar radiation (5.5–6.5 kWh/m²/day).

Green Energy for Government Institutions in Rajasthan - 

1. Solar Rooftop Systems for Public Buildings -

Government offices, educational institutes, health centres, and administrative blocks can install solar rooftop systems to power lighting, air conditioning, and basic operations.

Components - 

- High-efficiency monocrystalline panels

- Net-metering inverters connected to the grid

- Minimal battery storage (optional for critical loads)

 

Advantages - 

- Zero fuel cost

- Quick return on investment (ROI within 5–7 years)

- Government can earn credits by feeding surplus electricity into the grid

2. Hybrid Solar - Wind Systems in Desert Regions

Districts like Jaisalmer, Bikaner, and Barmer can benefit from combined solar and wind systems.

Setup -

- 5–20 kW systems with vertical-axis wind turbines

- Works efficiently during both sunny days and windy nights

Cost-Effective -

- Suitable for low-connectivity areas and off-grid institutions

- Reduces diesel generator dependency

3. Solar Streetlights and Water Heating - 

- Solar-powered LED streetlights with dusk-to-dawn and motion sensors save power in municipal areas and campuses.

- Solar water heaters can meet daily hot water needs in hostels, guest houses, and canteens within government facilities.

4. Smart Energy Monitoring and IoT Integration -

Digital Energy Management Systems (EMS) allow real-time monitoring of energy use across government buildings.

Features -

- Smart meters

- Sensors for HVAC systems and lights driven by (IoT) Internet of Things

- Centralised dashboards for analytics. 

This approach helps optimise energy usage, detect wastage, and enhance efficiency with minimal intervention.

Environmental and Financial Impact - 

Benefit - 

- Carbon Reduction - 1 kW solar = ~1.5 tonnes CO₂ saved/year

- Cost Savings - 30–60% reduction in electricity bills

- Employment - Local jobs in solar installation and O&M

- Grid Independence - Less power outages, lower losses

- Eco-Preservation - Cleaner air, lower land degradation

Low-Investment Models for Quick Implementation - 

To minimise upfront costs, the government can adopt Public-Private Partnership (PPP) and RESCO (Renewable Energy Service Company) models -

- RESCO bears installation and maintenance costs.

- The government pays only for consumed electricity at a discounted rate.

- Eligible for MNRE subsidies and State Green Energy Incentives.

    This makes the shift to clean energy budget-friendly, scalable, and low-risk.

        Transitioning to green energy in Rajasthan’s government sector is not just an ecological necessity - it’s an economically sound decision. With the state's vast renewable potential, especially in solar energy, government premises can lead the way toward a cleaner, smarter, and self-reliant energy future. The implementation is cost-effective, environmentally beneficial, and socially responsible. 

        By setting an example, Rajasthan can inspire other states in India to adopt similar green energy transformation plans, contributing to national and global sustainability goals.