15 MVA Step Up Power Transformer-4.16/69 kV | Guyana 2023

Stable power, empowering the future—choose our power transformers to light up every watt of energy!

01 General

1.1 Project Description

This 15 MVA step up power transformer was manufactured by us in 2023, the rated power of the transformer is 15 MVA, the primary voltage is 4.16 kV with +4×1.667% to -12×1.667% tapping range(OLTC), the low voltage is 69 kV. We have produced this OLTC step up power transformer in the material structure has taken a series of major changes, with light weight, small size, small partial discharge, low loss, low noise, high reliability, sudden short-circuit singularity protection, can reduce a large number of power grid losses, operating costs and economic benefits. YNd11’s connection mode provides good grid compatibility, while suppressing third harmonics and effectively improving grid operation quality. The high voltage side (Y) is a star connection with a neutral point that can be grounded directly or through a ground resistance to provide a stable high voltage output.

1.2 Technical Specification

15 MVA step up power transformer specification and data sheet

1.3 Drawings

15 MVA step up power transformer diagram drawing and size.

02 Manufacturing

2.1 Core

Our company adopts high-conductive volt-oriented cold-rolled silicon steel sheet, no-hole binding, frame structure, d-shaped yoke structure for coil instead of large-area platform, stepped joints. The core has small burr and low lamination coefficient. The no-load loss, the no-load current and the noise level are effectively reduced by the multi-stage joints of the iron core.

2.2 Winding

1. Continuous winding design: The tangle one continuous type and the inner plate one continuous type design are used, which helps to improve the longitudinal capacitance distribution of the coil under the impulse voltage. This design can reduce the concentration of electric fields, so that the coil has better electrical performance at high pressure. 2. Guided oil circulation structure: guided oil circulation structure is used to help reduce winding temperature rise. This design maintains the temperature inside the coil and helps to improve the safety and stability of the transformer.

2.3 Tank

1. Sealing performance: The oil tank is sealed with a stop limit to ensure that the transformer insulating oil can be effectively sealed inside the oil tank to avoid leakage and oxidation of insulating oil. 2. Anti-corrosion treatment: The oil tank is made of corrosion-resistant materials, and the paint treatment required for household appliances is used to enhance the corrosion resistance of the oil tank and extend the service life. 3. Leak detection test: the weld and seal of the tank have undergone three leak detection tests (fluorescence, positive pressure, negative pressure leakage test) to ensure tightness and safety.

2.4 Final Assembly

The final assembly of an oil-immersed power transformer produced by a transformer company typically involves several key steps: 1. Core Assembly: The core assembly is typically the first step in the final assembly process. This involves the stacking and clamping of the transformer core, which is composed of high-grade electrical steel laminations. The core must be assembled to precise specifications to ensure optimal magnetic properties and minimal core losses. 2. Windings Installation: The process involves installing the high-voltage (HV) and low-voltage (LV) windings onto the core. The windings are typically insulated copper conductors that are carefully placed, layered, and connected according to the transformer design. 3. Tank and Radiator Installation: The transformer tank, along with any associated radiators or cooling fins, is installed at this stage. The tank provides housing for the core and windings and can be sealed to contain the insulating oil. 4. Insulation, Connections, and Accessories: Insulating structures, such as bushings, leads, tap changers, and other accessories are installed and connected to the windings. Additional insulation and supports are added to ensure safe and reliable operation. 5. Oil Filling and Sealing: The transformer is filled with insulating oil through a carefully controlled process. Once filled, the transformer is sealed to prevent moisture ingress and to maintain oil integrity.

03 Testing

Insulation resistance test: used to detect the quality of insulation materials to prevent insulation breakdown. It is necessary to ensure that the transformer is offline and use appropriate resistance testing instruments.

Positive voltage test: High voltage is applied to the transformer during the test to test its insulation performance at rated voltage. This requires strict adherence to safe operating procedures and guarantees that test equipment meets standards.

Negative pressure test: This test item examines the insulation performance of the transformer at low voltage. It is also necessary to take appropriate safety measures to ensure that the test is carried out safely.

Ac resistance test: Test the grounding resistance of the winding to ensure the reliability of the grounding system.

Power loss and no-load current tests: These tests are used to measure the no-load performance and load performance of a transformer.

Load test: By applying the rated load, the performance parameters of the transformer under the rated load conditions are measured.

04 Packing and Shipping

4.1 Packing

The packing and transportation of an oil-immersed power transformer produced by a transformer company involves several important steps to ensure the safe and secure delivery of the equipment. Below is a general description of the process: Packing: Once the transformer has undergone final assembly, including testing and quality checks, it is prepared for packing. The transformer components, including the tank, core, windings, and associated accessories, are carefully secured and protected for transportation. The packing materials, such as wooden crates, foam padding, and strapping, are selected to provide adequate cushioning and protection. Preservation and Corrosion Protection: The transformer components are treated with appropriate preservation agents to protect against corrosion during transport and storage.

4.2 Shipping

Securing for Transport: The transformer components are secured within the packaging to prevent movement and to ensure stability during transportation. A secure and balanced arrangement is maintained to prevent undue stress on any part of the transformer. Identification and Documentation: Each packaged component is labeled, and detailed documentation is prepared, including packing lists, shipping instructions, and any required permits or certifications for transportation. Loading and Transport: The packaged components are loaded onto suitable transport vehicles, such as flatbed trailers or shipping containers, using cranes or other handling equipment. Specialized transportation may be required for oversized or heavy transformers. Handling and Unloading: During transport, the transformer components are handled with care to prevent damage. Upon arrival at the destination, care is taken during unloading to ensure safe and proper handling

05 Site And Summary

Preparation: Ensure the foundation is flat and stable, and all tools are ready.

Transportation and Hoisting: Transport the transformer to the site, hoist it into position, and secure it.

Attachment Installation: Install accessories such as cooling devices, oil conservator, and bushings.

Electrical Connection: Complete the connections for high and low voltage cables or busbars and ensure proper grounding.

Oil Filling and Inspection: Fill the transformer with insulating oil and check oil levels and quality.

Testing and Commissioning: Perform electrical tests such as insulation, resistance, and ratio tests.

Trial Operation: Conduct trial operation under load and confirm all parameters before final commissioning.