Transformer Installation: All you need to know about installing power transformers

Transformer Installation: All you need to know about installing power transformers

In this article, we delve into the intricate process of transformer installation, a crucial task in establishing and maintaining robust electrical systems. We will explore the essential steps from initial planning and site preparation to the final commissioning and maintenance strategies.

Important transformer tests

Before the installation of a power transformer, various essential tests are conducted to verify its design, construction, and performance. These tests are generally categorized into standard and special tests.

Standard Tests

These are routinely performed on each transformer unit to confirm compliance with specifications and standards. The key standard tests include:

  1. Voltage Ratio Test: Assesses the voltage ratio between primary and secondary windings at different taps.
  2. Polarity Test: Determines the current flow direction in primary and secondary windings, crucial for correct parallel operation and connection.
  3. Phase Relation Test: Checks the angular displacement between primary and secondary voltages in three-phase transformers, essential for parallel operations.
  4. No-Load Current Test (Excitation Current Test): Measures the primary winding’s current draw under no-load, rated voltage conditions to evaluate core losses and magnetizing characteristics.
  5. DC Resistance Test: Assesses the DC resistance of each winding to calculate winding temperature rise, copper losses, and impedance.
  6. Impedance and Short-Circuit Test: Measures impedance voltage or short-circuit voltage, informing protective device sizing and protection coordination.
  7. Full-Load Loss Test (Load Loss Test): Evaluates total power loss under full-load conditions, encompassing copper and stray losses.
  8. Voltage Regulation Test: Determines voltage changes in the secondary winding under full-load at varying power factors, indicating voltage stability.
  9. High-Potential Tests (Applied and Induced Potential Tests): Test the insulation system’s dielectric strength by applying high AC voltages to windings.

Special Tests

These are conducted based on specific applications, designs, or customer requirements for certain transformers. Notable special tests include:

  1. Impulse Test: Simulates lightning or switching surges using high voltage impulses to assess transient overvoltage withstand capabilities.
  2. Acoustic Test (Sound Level Test): Measures the sound emission under various operational conditions, important for installations near residential or office areas and to detect core issues.
  3. Temperature Rise Test: Monitors oil and winding temperature under rated load and ambient conditions to verify design limits and cooling system efficiency.
  4. Corona (Partial Discharge) Test: Identifies and locates corona discharges in medium and high-voltage transformers, a key factor in insulation degradation.
  5. Insulation Resistance Test: Measures insulation resistance, providing insights into insulation dryness and cleanliness, and serves as a baseline for future comparisons.
  6. Dissolved Gas Analysis: Investigates gases dissolved in transformer oil to diagnose issues such as overheating, arcing, partial discharge, and oil degradation.

Each of these tests plays a crucial role in ensuring the transformer’s reliability, safety, and efficiency before it is put into service.

Procedure for transformer installation

Planning and Design

During the planning and design stage of transformer installation, it’s crucial to accurately determine the transformer’s capacity and type (such as step-up, step-down, or isolation) based on the specific electrical load and application needs. Selecting a suitable installation site is vital, taking into account accessibility, safety, ventilation, and environmental conditions. Additionally, the installation plan must adhere to local and national electrical codes and standards to ensure compliance and safety. This careful planning is fundamental for a successful transformer installation.

Preparation of the Site

In preparing the site for transformer installation, safety is paramount. It involves implementing rigorous safety protocols, including disconnecting existing power sources to secure the working area. Additionally, preparing a robust foundation is crucial. This step may require constructing a concrete pad or setting up other support structures to ensure a stable and level base capable of supporting the transformer’s weight. These preparatory measures are essential for a safe and effective installation.

Transportation and Positioning

For the transportation and positioning phase, the transformer must be securely conveyed to the installation site with suitable lifting and moving tools. This ensures safe transit and minimizes the risk of damage. Once at the site, precise positioning is critical. The transformer should be meticulously set onto its foundation, with special attention to its alignment and level.

Electrical Connections

In the electrical connections stage, it is imperative to adhere closely to the manufacturer’s wiring diagrams. This ensures accurate connections between primary (input) and secondary (output) circuits. The connection of the transformer’s windings demands careful attention; each must be securely connected, tightly fastened, and correctly configured. Additionally, proper grounding of the transformer is essential. This critical step safeguards against electrical shocks and guarantees the safe operation of the transformer.

Cooling System Setup (If Applicable)

For transformers that require a cooling system, particularly liquid-filled types, setting up the cooling equipment is a key step. This involves installing and testing components such as radiators, fans, or pumps, ensuring they function effectively. It’s also crucial to conduct a thorough inspection of the cooling system, checking for any leaks and confirming efficient operation.

Final Inspection and Safety Check

This step is critical to confirm that the installation complies with all relevant safety standards and electrical codes. It includes a detailed review by a qualified electrician or inspector to ensure every aspect of the installation meets the required safety benchmarks.


In the commissioning phase, the transformer undergoes initial energizing, starting with a light load to test its operational efficacy. This cautious approach allows for monitoring and adjustment in a controlled manner. Following this, the transformer is subjected to load testing, where the load is incrementally increased up to its rated capacity. This gradual escalation is crucial for assessing the transformer’s performance under various load conditions, ensuring it operates efficiently and reliably at full capacity.

Documentation and Record Keeping

For effective management and future reference, meticulous documentation and record-keeping are essential throughout the transformer installation process. This involves maintaining comprehensive records of every step of the installation, including details of the tests performed and any adjustments or modifications made. Additionally, preserving the transformer’s operating manuals and maintenance guides in an accessible location is crucial. These documents are invaluable resources for ongoing maintenance, troubleshooting, and ensuring the transformer’s long-term operational integrity.

Regular Maintenance Planning

Establishing a regular maintenance schedule is vital for ensuring the transformer’s longevity and optimal performance. This schedule should detail routine checks and servicing to maintain the transformer’s efficiency and reliability. Equally important is equipping maintenance staff with specialized training tailored to the specific type and model of the transformer. This training enables the staff to effectively monitor, maintain, and address any issues that may arise, ensuring the transformer’s sustained and safe operation.


In conclusion, the installation of a transformer is a complex yet vital task, requiring thorough planning, precision, and adherence to safety protocols. Through diligent execution and ongoing maintenance, a well-installed transformer ensures efficient and reliable power distribution, playing a crucial role in the electrical infrastructure.

At TTES, we have over 100 combined years of experience manufacturing, maintaining, and repairing Zig zag transformers and other types. If you’re looking for industry-leading lead times of just 20 weeks on average, don’t hesitate and reach out to us for a free quote!

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