Substation and its components:

Switchyard:

Switchyard is the feed bay where electricity is transferred from substation (sending end) to the
receiving end through transmission lines. Switchyard is the intermediate point between the
substation and transmission.

Objects inside switchyard:

1. Transformer :

Defects to be inspected:

 Oil leakage : Oil leaks in transformers are usually caused by manufacturing defects, such as
poor welding, insufficient sealing, or loosely torqued bolts. These faults can be fixed by
welding and adding fillers and sealants that are compatible with oil and water.
  Overheating:
Use of thermo graphic instrument we can measure the temperature of transformer for
overheating. To prevent overheating, proactive measures are crucial. Regular monitoring
of transformer operating temperatures is essential, and any deviations from normal
ranges should be investigated promptly. Ensuring proper load management and avoiding
overloading is vital to prevent excessive heat generation. Adequate ventilation and
cooling systems must be in place and maintained to dissipate heat effectively. Installing
temperature monitoring and alarm systems can provide early warnings of potential
overheating issues. Routine oil analysis can also help detect problems like hotspots or
deteriorating insulation. By implementing these preventative measures, the risk of
overheating in transformers can be significantly reduced, enhancing their reliability and
lifespan while minimizing the potential for costly failures.

 To inspect for insulation deterioration in a

Insulation Deterioration:
transformer, the most reliable method is to perform a Dissolved Gas
Analysis (DGA) test, which analyzes the dissolved gases in the
transformer oil to identify potential issues like overheating, arcing,
and degradation of the cellulose paper insulation, providing valuable
insights into the health of the transformer's insulation; alongside this,
visual inspections, insulation resistance testing, and power factor
measurements can also be used to detect signs of insulation
degradation.
Key methods for inspecting transformer insulation deterioration:
 Dissolved Gas Analysis (DGA):
Considered the most important test for detecting insulation degradation,
DGA analyzes the types and concentrations of dissolved gases in the
transformer oil, which can indicate specific problems like overheating,
partial discharges, or arcing.
 Insulation Resistance Test:
Measures the resistance of the transformer's insulation by applying a high
voltage and observing the leakage current; a low resistance value indicates
potential insulation degradation.
 Power Factor Measurement:
Assesses the quality of the transformer's insulation by measuring the power
factor; a low power factor suggests increased insulation losses and
potential degradation.
 Visual Inspection:
Checking for signs of external damage, leaks, loose connections, and the
condition of the transformer tank and cooling system can provide clues
about potential insulation issues.
 Oil Analysis:
Analyzing the color, acidity, moisture content, and dielectric breakdown
voltage of the transformer oil can reveal signs of contamination or
degradation.
Important factors to consider during inspection:
 Transformer age and operating history: Older transformers are
more prone to insulation degradation.
 Environmental conditions: High temperature, humidity, and
pollution can accelerate insulation deterioration.
 Load profile: Frequent load fluctuations can stress the insulation.
High Moisture Levels:Silica gel breather crystals turns pink from blue

Key points about high moisture in transformers:

 Impact on insulation:

Moisture absorbed by the paper insulation within the transformer significantly reduces its
dielectric strength, making it more prone to electrical breakdown.

 Causes of moisture ingress:

 Leaks in seals or gaskets

 Environmental conditions with high humidity

 Aging of the insulation paper which naturally generates moisture

 Signs of high moisture:

  Increased dissolved gas levels in the transformer oil

 Abnormal readings on a moisture analysis test

 Increased partial discharge activity

 Consequences of high moisture:

 Reduced transformer lifetime

 Increased risk of electrical faults like arcing and flashovers

 Potential for overheating and damage to internal components

What to do about high moisture levels:

 Regular monitoring:

Routine testing of transformer oil to measure moisture content using specialized

equipment

 Drying process:

If high moisture is detected, a dedicated drying process may be required using

specialized equipment to remove moisture from the oil and insulation

 Maintenance of seals and gaskets:

Regularly inspect and maintain seals and gaskets to prevent moisture ingress

 Environmental control:

Manage humidity levels in the transformer area where possible

 Corrosion:Visual inspection

To inspect for corrosion in a transformer, a visual examination of all metallic parts of the
transformer tank body, including the tank itself, radiator fins, fans, chassis, and other
components, should be conducted, focusing on signs of rust and degradation, particularly in
areas exposed to moisture or harsh environments; additionally, more thorough inspections
might involve using non-destructive testing methods like magnetic particle inspection or liquid
penetrant testing to detect hidden corrosion
 areas.

Key points to check during a transformer corrosion inspection:

 Visual assessment:

 Look for visible rust on the tank exterior, including the base, seams, and corners.

 Check the condition of paintwork for peeling or blistering, which can indicate
underlying corrosion.

 Inspect the condition of hardware like bolts, nuts, and mounting brackets for signs
of rust.

 Examine the radiator fins for corrosion, especially if they are exposed to the
elements.

 Check the condition of the transformer bushings and connections for signs of corrosion.



 Overloading:Load more than the capacity

Inspecting for transformer overloading involves primarily monitoring the transformer's

temperature using dedicated sensors or infrared cameras, alongside visual checks for signs
of excessive heat like discolored paint, loose connections, and unusual noises, while also
analyzing load data through current measurements to assess if the transformer is operating
beyond its rated capacity.
Key aspects of a transformer overload inspection:
 Temperature monitoring:

 Temperature sensors: Most transformers are equipped with temperature

sensors (like winding hot spot sensors) that provide real-time data on the internal
temperature, allowing for direct comparison to the manufacturer's rated
temperature limits.

 Infrared thermography: Using an infrared camera to scan the transformer's

external surface can identify areas of excessive heat generation, which could
indicate overloading.

 Visual inspection:

 Paint discoloration: Check for areas of discolored paint on the transformer

casing, which could signify high operating temperatures.

 Loose connections: Inspect all connections for signs of overheating like loose
or corroded terminals.

 Abnormal sounds: Listen for unusual noises like buzzing or humming sounds
that could indicate overloading.

 Oil leaks: Check for oil leaks around seals or bushings, which could be a sign of
excessive pressure due to high temperatures.

 Load data analysis:

 Current measurements: Monitor the current drawn by the transformer using

current transformers to compare against the rated current.

 Load monitoring systems: Utilize dedicated load monitoring systems to track

transformer loading over time and identify potential overload situations.
Important considerations:

 Ambient temperature:

Always factor in the ambient temperature when evaluating transformer temperatures, as

higher ambient temperatures can lead to increased transformer heating even at normal load
levels.

 Transformer design:

Different transformer designs have varying overload capabilities, so consult the

manufacturer's specifications for accurate interpretation of inspection data.

 Regular inspections:

Routine inspections are crucial to catch potential overload issues before they cause
significant damage to the transformer.
What to do if overloading is detected:

 Reduce load:
If overloading is confirmed, take steps to reduce the load on the transformer by redistributing
power to other transformers or adjusting power consumption in the area served.

 Maintenance checks:

Perform thorough maintenance checks to ensure the transformer is functioning optimally,

including cleaning cooling systems and tightening connections.

 Upgrade considerations:

If the load consistently exceeds the transformer's capacity, consider upgrading to a larger
transformer with a higher capacity

 Oil Contamination

DGA, To inspect for oil contamination in transformers, technicians typically take an oil
sample and analyze it in a laboratory, performing tests like dielectric breakdown voltage,
moisture content, dissolved gas analysis (DGA), interfacial tension, and specific gravity,
which reveal the presence of contaminants like water, particles, and degradation products
within the oil, indicating potential issues with the transformer's insulation quality and overall
health; visual inspection of the oil for discoloration or sediment can also provide initial clues
about contamination levels.
Key points about oil contamination inspection in transformers:

 Oil sampling:

A small sample of transformer oil is extracted using a specialized sampling device to ensure
representative data.

 Laboratory analysis:

 Dielectric breakdown voltage (BDV): Measures the voltage at which the oil
breaks down, indicating the presence of contaminants that reduce insulation
strength.
  Moisture content: Detects the amount of water dissolved in the oil, which can
significantly impact insulation properties.

 Dissolved gas analysis (DGA): Analyzes the types and concentrations of gases
dissolved in the oil, which can reveal information about potential faults like
overheating, arcing, or partial discharges.

 Interfacial tension: Indicates the presence of polar contaminants and oxidation

products in the oil.

 Specific gravity: Checks the oil's density, which can be affected by

contamination.

 Color and appearance: Visual observation of the oil sample for discoloration or
sediment.

 Interpretation of results:

Comparing the test results to established standards helps determine the level of oil
contamination and potential risks to the transformer.

 Action based on findings:

Depending on the analysis, actions may include:

 Oil filtration: Removing contaminants by filtering the oil.

 Oil replacement: Completely changing the transformer oil if contamination is

severe.

 Investigating potential fault sources: Further diagnostics to identify the root

cause of contamination.

 Mechanical Damage:Any loose or damaged parts of transformer A mechanical damage

inspection of a transformer involves a visual assessment of the transformer's exterior,
looking for signs of physical damage like dents, cracks, corrosion, loose components,
deformed tank shapes, oil leaks, and checking the condition of the cooling system,
bushings, connectors, and control devices for any signs of wear or deterioration.
 Key areas to inspect for mechanical damage:

 Transformer tank:

 Dents or bulges on the tank body

 Signs of corrosion or rust

 Cracks or splits in the tank welds

 Misalignment of tank components

 Deformation of the tank shape

 Cooling system:
 Damaged cooling fins on radiators

 Loose or malfunctioning cooling fans

 Oil leaks from cooling system components

 Bushings:

 Cracked or chipped porcelain insulators

 Loose or damaged bushings

 Signs of arcing or overheating on the bushing surfaces

 Connectors and terminals:

 Loose or corroded connections

 Damaged terminal lugs

 Signs of overheating on the connections

 Mounting hardware:

 Loose or damaged mounting bolts

 Improper alignment of the transformer on its foundation

 Inspection methods:

 Visual inspection:

 A thorough visual examination of the transformer from all angles, using binoculars or
other tools to access hard-to-reach areas.

 Physical checks:

 Checking for loose components, tapping on the tank to identify potential internal damage,
and assessing the overall stability of the transformer.

 Oil level check:

 Checking the oil level in the transformer tank to ensure it is within the acceptable range.

 Oil sample analysis:

 Taking an oil sample to analyze its condition for signs of degradation or contamination
which can indicate internal mechanical damage.
 Important considerations:

 Safety precautions:

 Always follow safety procedures when inspecting a transformer, including de-energizing

the unit, using proper protective equipment, and being aware of potential hazards.
  Documentation:

 Record all observations and findings during the inspection, including photographs of any
damage identified.

 Maintenance schedule:

 Regular mechanical inspections should be part of a preventative maintenance plan for

transformers to identify and address potential issues before they escalate.

What do you inspect on a transformer?

The visual inspection of a transformer is as simple as going out and walking around the unit
to look at three key areas: paint condition, leaks, and gauges(Winding temperature and Oil
temperature gauges.)

 OLTC: An inspection of an On-Load Tap Changer (OLTC) in a

transformer involves a thorough visual assessment, followed by electrical
tests like DC winding resistance measurements to check for contact
degradation, dynamic resistance measurements to analyze the operation
during tap changes, and sometimes even oil analysis to monitor the overall
health of the OLTC mechanism, all aimed at identifying potential issues with
the tap changer's functionality and preventing unexpected failures during
operation.
 Key aspects of an OLTC inspection:
 Visual inspection:
 Check for signs of physical damage like dents, corrosion, or loose
connections on the OLTC housing.
 Assess the condition of the oil level in the tap changer head and the
surrounding area for any leaks.
 Observe the condition of the operating mechanism and moving parts for
wear and tear.
 Electrical tests:
 DC winding resistance measurement: This test measures the resistance
of the transformer windings at each tap position to identify potential
problems with contacts or loose connections.
 Dynamic winding resistance measurement: This test monitors the
resistance of the winding while the OLTC is changing tap positions, allowing
detection of issues with the diverter switch or transition resistors.
 Sweep frequency response analysis (SFRA): This test can be used to
assess the mechanical integrity of the tap windings and their leads.
 Mechanical checks:
 Operation test: Manually operate the OLTC through its entire tap range to
check for smooth transitions and proper functioning.
 Torque measurement: Monitor the torque required to operate the tap
changer to identify potential mechanical issues like worn gears or bearings.
 Contact wear assessment: Analyze the condition of the OLTC contacts for
excessive wear or pitting.
 Important considerations:
  Oil analysis:
 Regularly sample the transformer oil to check for contaminants that could
affect the OLTC operation.
 Operating history:
 Review the tap changer's operational data, including the number of tap
operations and the frequency of reversals, to identify potential wear
patterns.
 Maintenance schedule:
 Establish a regular maintenance schedule for the OLTC, including cleaning,
lubrication, and contact replacement as needed.
 Common defects in an on load tap changer (also known as a no-load tap changer)
include: mechanical issues like contact wear, misalignment of contacts, problems
with the operating mechanism, faulty linkage, poor lubrication, issues with the
diverter switch, and potential for arcing due to improper operation during energized
switching; these can often be caused by inadequate maintenance or improper
handling when switching taps on a live transformer. Oil leakage is also required to
be inspected .

 Bushings:Visually look for signs of physical damage like cracks, leaks, loose
connections, or contamination on the bushing exterior. Here are some ways to inspect
bushings in transformers:
 Visual inspection
 Walk around the transformer and check the bushings, cooling system, paint condition,
leaks, breathers, and gauges.
 Capacitance and tan delta (C and tan δ) testing
 Measures the quality of the insulation system and dielectric properties of the bushings.
 Power factor (PF) testing
 Assesses the insulation integrity of the bushing.
 Partial discharge (PD) testing
 Measures the quality of the insulation system and dielectric properties of the bushings.
 Hot collar test
 Generates localized high-voltage stresses through the bushing or pothead to measure
dielectric losses.
 Oil dielectric test
 Tests an oil sample to determine its dielectric strength and assess the condition of the
insulation system.
 Infrared inspection
 Checks for loose connections by looking for bushings that get hotter than normal under
the same load.
 Bushing failures are a leading cause of transformer failures and forced outages. Regular
testing can help detect deterioration so bushings can be replaced before a catastrophic
failure.

  Cooling fans:Check if fans are getting on or not When inspecting cooling fans on a
transformer, you should primarily check if the fans rotate freely at full speed, with
minimal vibration, and ensure the blades are clean and not deformed; additionally, look
for signs of wear, corrosion, or unusual noises while the fan is running, and verify
proper functionality by operating the fan control switch to "manual" to test its speed
and operation.
 Key points to inspect:
 Rotation and speed:
 Engage the fan control switch to "manual" to activate the fan.
 Observe if the fan spins freely and reaches full speed within a few seconds.
 Blade condition:
 Check for any damage or deformation to the fan blades.
 Ensure the blades are clean and free of debris.
 Noise and vibration:
 Listen for any unusual noises or excessive vibrations while the fan operates.
 Visual inspection:
 Look for signs of wear, corrosion, or damage on the fan housing and motor.
 Motor functionality:
 Check if the motor starts smoothly and runs without any issues.
 Important considerations:
 Safety procedures:
 Always follow safety protocols when working around electrical equipment, including
de-energizing the transformer before inspection.
 Maintenance schedule:
 Regularly inspect cooling fans as part of your routine transformer maintenance
schedule.
 Documentation:
 Record any observed issues or concerns during the inspection for future reference.


 Radiator fins :Check for oil leakage , check for valves damage, check for physical damage
When inspecting a transformer's radiator fins, you should primarily check for signs of dirt,
debris, or excessive dust buildup between the fins, as this can significantly hinder the
cooling efficiency of the radiator, potentially leading to overheating issues; a visual
inspection should also look for any physical damage to the fins, such as bending or missing
sections.
 Key points to focus on during radiator fin inspection:
 Cleanliness:
 Use a flashlight to thoroughly examine the spaces between fins for dirt, dust, or other
contaminants.
 Check for any large debris stuck within the fins that might obstruct airflow.
 Physical integrity:
 Look for any bent, damaged, or missing fins.
 Check for signs of corrosion on the fins, which can affect their heat transfer capabilities.
 Overall condition:
 Assess the overall appearance of the radiator fins, noting any significant buildup of dirt or
debris that could impact cooling performance.
 Important considerations:
 Maintenance schedule:
 Regularly scheduled cleaning of the radiator fins is crucial to ensure optimal cooling.
 Cleaning method:
 Depending on the level of dirt, cleaning may involve compressed air, a soft brush, or
specialized cleaning solutions.
 Safety precautions:
 Always follow safety procedures when inspecting and cleaning transformer components,
including wearing appropriate protective gear.
 Conservator tank: When inspecting a transformer's conservator tank, the primary focus is
to check the oil level using the provided gauge, ensuring it is within the recommended
range, and looking for any signs of leaks, damage, or contamination, while also visually
assessing the tank's exterior for corrosion or physical damage; the oil level should be high
enough to accommodate thermal expansion and contraction of the transformer oil without
contacting outside air.
 Key points to check during a conservator tank inspection:
 Oil level:
 Use the oil level gauge to verify the oil level is within the specified operating range.
 Note any significant fluctuations in oil level which could indicate a leak.
 Visual inspection:
 Check for any signs of external damage on the conservator tank like dents, cracks, or
corrosion.
 Observe the tank's seals and connections for any signs of leakage or deterioration.
 Gauge functionality:
 Ensure the oil level gauge is functioning correctly and accurately reading the oil level.
 If the gauge is malfunctioning, take necessary steps to repair or replace it.
 Contamination checks:
 Look for any visible signs of contamination in the oil, such as sediment or debris.
 Air vent functionality:
 If applicable, check the air vent on the conservator tank to ensure it is clear and functioning
properly.
 Important considerations:
 Safety precautions:
 Always follow safety procedures when inspecting a transformer, including de-energizing the
unit and taking appropriate precautions against potential electrical hazards.
 Maintenance records:
 Compare the current inspection findings with previous maintenance records to identify any
trends or potential issues.
 Professional expertise:
 If any concerns are identified during the inspection, consult with a qualified electrician or
transformer specialist for further evaluation and repairs

 2.Circuit Breakers: Visual inspection:

 Check for any visible damage to the breaker casing, terminals, and contact surfaces.
 Examine for signs of overheating, like discoloration or deformation.
 Verify proper alignment and mounting of the breaker.
 Inspect the condition of labels, nameplates, and safety markings

Mechanical inspection:
  Check the operation of the closing and opening mechanism, ensuring smooth
movement without sticking or binding.
 Verify the functionality of the tripping mechanism and auxiliary contacts.
 Assess the condition of the operating handle and interlock mechanisms

 Grounding checks:

 Verify that all grounding connections to the breaker are secure and in good
condition.

 Other considerations:

 SF6 gas pressure check (if applicable): Check the pressure level of the
insulating gas in SF6 circuit breakers.

 Cleaning and lubrication: Clean the breaker exterior and lubricate moving
parts as needed.

 Documentation: Record all inspection findings and test results for future
reference

3.Isolators or Disconnect switch: Also known as disconnection switches, these allow

sections of the substation to be de-energized for maintenance or repairs.

Key aspects of an isolator inspection in a switchyard:

 Visual inspection:

 Check for any visible damage to the isolator body, including cracks, dents, or
corrosion.

 Assess the condition of insulators for cracks, dirt accumulation, or signs of

flashover.

 Verify the alignment of contact blades and ensure they are clean and free of
debris.

 Examine the mounting hardware for tightness and proper securing.

 Mechanical operation:

 Manually operate the isolator to check for smooth opening and closing
movements.

 Verify the presence and functionality of interlocks, ensuring the isolator

cannot be operated in an unsafe sequence.

 Check for any excessive friction or binding during operation.

 Contact inspection:
  Assess the condition of contact surfaces for wear, pitting, or excessive
erosion.

 Check for proper contact pressure and alignment.

 Verify the integrity of the contact springs.

 Insulator inspection:

 Examine insulators for any visible damage, cracks, or contamination.

 Check for proper insulator stringing and spacing.

 Control circuit inspection:

 Verify the functionality of control wiring and connections.

 Test the control relays and auxiliary switches.

 Check for proper labeling of control circuits.

 Cleaning and maintenance:

 Remove any accumulated dirt, dust, or salt deposits from the isolator surfaces.

 Apply appropriate lubrication to moving parts as needed.

4. Switchyard structures: Made up of columns and beams that support the electric
equipment

Key aspects of a switchyard structure inspection:

 Visual assessment:

 Check for visible signs of corrosion, rust, paint deterioration, or damage on

structural members.

 Examine welds and connections for cracks, distortions, or improper

attachment.

 Look for signs of excessive vibration or movement in the structure.

 Assess the condition of concrete foundations and anchor bolts.

 Structural integrity:

 Verify that all structural members are properly aligned and within design
specifications.

 Check for any deflection or sagging in beams or columns.

  Assess the load-bearing capacity of the structure based on current equipment
and potential future expansions.

 Grounding system:

 Inspect grounding cables and connections for damage, corrosion, or loose

connections.

 Test grounding continuity throughout the switchyard using appropriate testing

equipment.

 Ensure proper grounding of all structural components.

 Specific areas of focus:

 Bus support structures: Check for any cracks, loose connections, or

misalignment of bus bars.

 Breaker mounting structures: Inspect for signs of wear, damage, or

improper alignment of circuit breakers.

 Disconnect switch supports: Examine the mounting points and mechanisms

for proper functionality.

 Transformer support structures: Assess the condition of the foundation and

anchor bolts for transformers.

Important considerations during inspection:

 Safety procedures:

Always follow strict safety protocols when inspecting a live switchyard, including de-
energizing circuits when necessary, proper PPE, and maintaining safe distances from
energized equipment.

 Documentation:

Record detailed observations, including photos and measurements of any identified issues,
for future reference and corrective action.

 Qualified personnel:

Ensure the inspection is conducted by trained personnel with expertise in high-voltage

switchyard operations and structural integrity assessment.

5.Auxiliary Equipment:
An inspection of auxiliary equipment in a switchyard involves a thorough visual
examination of supporting systems like battery banks, control panels, lighting systems,
communication equipment, earthing connections, and cooling fans, checking for any signs
of damage, wear, corrosion, loose connections, malfunctioning components, and ensuring
their proper functionality to support the main switching devices in the yard.

Key aspects of auxiliary equipment inspection in a switchyard:

 Visual inspection:

 Checking for physical damage, cracks, or deformations on equipment

enclosures and components.

 Assessing the condition of cables, wires, and connections for signs of fraying,
overheating, or loose terminations.

 Examining the cleanliness of equipment, looking for dust buildup that could
affect insulation.

 Verifying proper labeling and identification of components.

 Functional testing:

 Testing battery voltage and charging capabilities to ensure proper backup

power supply.

 Checking the functionality of control panel switches, relays, and alarms.

 Verifying the operation of lighting systems, including emergency lighting.

 Testing the communication system for clear transmission and reception.

 Assessing the performance of cooling fans and ventilation systems.

 Electrical measurements:

 Measuring insulation resistance of cables and equipment using a megger.

 Checking the continuity of earthing connections.

 Monitoring voltage and current levels on auxiliary circuits.

Specific auxiliary equipment to inspect:

 Battery banks: Check electrolyte levels, cell voltage, and charging system
functionality.
 Control panels: Inspect switchgear, relays, and wiring connections for proper
operation.
 Lighting systems: Test all lights, including emergency lighting, for proper
illumination.
  Communication systems: Verify communication channels, including radio,
telephone, and data links.
 Earthing system: Check all earthing connections for integrity and proper grounding
resistance.
 Cooling fans and ventilation systems: Assess fan performance and airflow.
 Monitoring systems: Review data from auxiliary equipment monitoring systems.

Important considerations:

 Safety procedures:

Always follow established safety protocols when inspecting switchyard equipment,

including proper lockout/tagout procedures and use of personal protective equipment.

 Maintenance records:

Refer to previous maintenance records to identify recurring issues and potential areas of
concern.

 Documentation:

Record findings and any necessary corrective actions in a detailed inspection report

6. Lightning Arrestors:

Key points to inspect during a lightning arrester check in a switchyard:

 Visual inspection:

 Check for cracks or damage to the porcelain housing.

 Examine the condition of the connecting hardware, looking for loose or

corroded connections.

 Assess the overall mounting and alignment of the arrester.

 Look for signs of overheating, discoloration, or leakage marks.

 Verify the integrity of the safety vent (if applicable).

 Grounding check:

 Inspect the grounding conductor connection to the arrester for proper tightness
and corrosion-free contact.

 Ensure the grounding system is properly maintained and connected to the

earth grid.
7. Current and voltage transformers:

Key points to inspect in a current and voltage transformer:

 Visual Inspection:

 Check for any visible damage to the transformer casing, bushings, or

mounting brackets including cracks, dents, corrosion, or signs of overheating
(discoloration).

 Inspect the condition of the paintwork for signs of peeling or rust.

 Verify the integrity of all seals and gaskets to prevent oil leaks.

 Look for any signs of contamination on the exterior, like dirt or debris.

 Connection Checks:

 Verify that all primary and secondary connections are tight and properly
secured.

 Check for any loose or corroded connections on the terminal blocks.

 Ensure proper grounding of the transformer casing and secondary

connections.

 Burden Check (Current Transformer):

 Verify that the connected burden (load on the secondary circuit) is within the
rated capacity of the current transformer.

 Check if the secondary circuit is properly terminated (not open-circuited).

 Ratio Test (Voltage and Current Transformer):

 Use a dedicated test equipment to verify the transformation ratio between the
primary and secondary windings to ensure accurate measurement.

 Insulation Resistance Test:

 Measure the insulation resistance of the transformer windings to assess the

overall insulation quality.

 Oil Level Check (For Oil-Immersed Transformers):

 Check the oil level within the transformer tank and ensure it is within the
specified range.

 Take an oil sample for analysis to assess its condition and potential
degradation.
  Operational Checks:

 Monitor the secondary output voltage of the transformers using a suitable

meter to verify that it is within the expected range under normal operating
conditions.

Safety Considerations:

 Always follow proper safety procedures when inspecting high voltage equipment.
 Ensure the switchyard is de-energized before performing any inspections.
 Use appropriate personal protective equipment (PPE) including insulated gloves,
safety glasses, and arc flash protection.
 Never work on a transformer alone, always have a qualified person present to assist in
case of emergencies.