22 MVA 115 kV Oil Filled Power Transformer
- Primary Voltage Ratings: 115kV
- Secondary Voltage Ratings: 6.9kV
- H.V. TAP RANGE: 115 kV ±2×2.5%
- CONNECTION TYPE: YNd1
- BIL: 550/95kV
- Standards: CSA
- Application: Canadian Hydropower Plant
- Power Rating: 22 MVA
- Cooling Method: ONAN/ONAF1/ONAF2
This is a heavy duty 3 phase power transformer designed and developed by Daelim Transformers for a hydropower plant in Canada. It's an oil immersed type power transformer that has been designed and developed for reliable performance in challenging operating environments of Canada. This Power Transformer is featured with high surge withstand capabilities, multiple cooling systems, wide tap range, and compliance with CAN/CSA C88 and other related international and national standards as per Canadian laws. Energy efficiency design and robust manufacturing make it an ideal transformer for applications like the Canada national grid station.
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Power Rating
This three phase power transformer offers three different power rating operations. This is specially needed when the transformer is being designed for an application like power generation setup like a hydropower plant where power generation capacity and load capacity both change.
The transformer offer power ration of
- 12.5 MVA
- 16.5 MVA
- 22 MVA
Three different power ratings has one specific voltage value for all but three different current values (one for each rated power rating). The power rating of 12.5 MVA works here as the base line.
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22 MVA 115 kV Oil Filled Power Transformer
Voltage and Current Rating
Voltage regulation is a key aspect of power reliability, so this transformer is designed with a 5 position tap changer on the high voltage winding side, allowing adjustment of voltage from 109 kV to 120 kV. This is highly important for applications like transmission grid and to facilitate the precise control over primary side voltage.
| Winding | Voltage | Configuration |
| HV | 120/117/115/112/109 kV | Wye (grounded) |
| LV | 6.9 kV | Delta |
Tap positions are as follows.
| Tap Position | Voltage (V) | Current @ 12.5 MVA (A) | Current @ 16.5 MVA (A) | Current @ 22 MVA (A) |
| 1 | 120,750 | 59.8 | 78.9 | 105.2 A |
| 2 | 117,875 | 51.2 | 80.8 | 107.8 A |
| 3 | 115,000 | 62.8 | 82.8 | 110.4 A |
| 4 | 112,125 | 64.4 | 85.8 | 113.3 A |
| 5 | 109,250 | 66.1 | 87.2 | 116.3 A |
On the low voltage winding side, the transformer delivers 6.9 KV of voltage for all three power ratings with different current ratings. This ensures that the required output is delivered reliably under all operating scenarios.
| Voltage (V) | Current @ 12.5 MVA | @ 16.5 MVA | @ 22 MVA |
| 6900 | 1045.9 A | 1380.6 A | 1882.7 A |
Internal Current Transformers
The transformer is also designed with a built-in current transformer for accurate monitoring, protection, and metering. Multiple ratios offer flexibility in current sensing across both the high and low voltage sections. These CT conform to C100 and C200 accuracy classes that ensure precision in protection replat operations and systems.
Cooling System
The transformer is designed in a manner that it can utilize three different cooling mechanisms based on the power rating and load requirement. The transformer has one ONAN cooling system designed with fins on the transformer tank and two ONAF systems. One ONAF system is for when power rating is moderate and both ONAF systems are used when the transformer is operating on maximum power.
| Cooling Method | Rated Power Output |
| ONAN | 12.5 MVA |
| ONAF-1 | 16.5 MVA |
| ONAF-2 | 22 MVA |
The transformer uses about 8000 Kgs of mineral oil for the transformer cooling system. Sealed inside the transformer tank and work based convection mode of heat transfer.
Weight of Transformer
Each part of the transformer is precisely designed for balance between weight and structure integrity. Weight of each part is mentioned below in kg and combined weight of the transformer when fully assembled and when transported is mentioned separately.
| Component | Weight |
| Tank & Fittings | 8,900 kg |
| Transformer oil | 8,000 kg |
| Core & Coils | 14600 kg |
| Transport Weight | 27,500 kg |
| Total Weight | 32,500 kg |
Engineering Design
This power transformer is very carefully designed for reliability, safety, and efficiency due to the nature of its application. Some common features are as follows.
- Transformer winding is made from highly quality and pure copper material ensuring that no material defect is present in copper before and after winding of the transformer is done.
- Similarly the core of the transformer is very carefully sized, designed, and manufactured using highest standard steel sheets to ensure quality manufacturing.
- The transformer tank design, size, and manufacture is done to ensure reliability in the extreme environmental conditions of Canada where temperature can go well below zero.
- Transformer tank surface is heat treated and coated with rust resisting materials to increase the life of the tank in outdoor applications.
- All types of safety devices like thermal sensors, surge arrestors, lightning arrestors, transformer grounding etc are installed with IoT integration for remote monitoring and control.
- Oil use in the transformer is free from PECs at the time of delivery and operationalization.
- YNd1 vector group offering delta wye transformation with a 30 degree phase shift. This is considered perfect for grid balancing and synchronization.
Compliance and Safety
The power transformer designed and developed by Daelim Transformers can satisfy all international standards as we follow each and every standard procedure during transformer design and manufacturing.
Some of the basic standards that our transformer satisfies are mentioned below.
- ANSI / IEEE C57.12.00 for general power transformer requirements
- ANSI / IEEE Std.32 standard requirements and testing procedure of transformers
- CAN/CSA C22.2 No.94 special purpose enclosures
- CAN/CSA C88 Power Transformer standards
- IEEE C62.82.1 standards for insulation coordination
- IEEE C62.11 and IEEE C62.22 standard for metal oxide surge arresters and alternating current system
Applications
Power Transformer of this specification can be used in application including
- Hydroelectric power plant
- National Grid Stations
- National grid substations
- Diesel Generator power plants
Why Choose Daelim?
Having a team of engineers that has decades of experience in designing, manufacturing, assembling, testing, transporting, installing and operationalizing electrical transformers make Daelim a prominent name in the electrical transformer world.
Our team has already completed hundreds of projects all around the globe and we offer quality services like no other. We combine
- Custom engineering and CAD based simulation to ensure efficient designing of transformer parts
- Full pre and post shipment testing as per international standards
- Complete network of expert global logistics and support for transformer supply and installation.
- Compliance with IEEE, UL, CSA, and IEC standards
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If you need any help related to power transformers, then contact us and we will be happy to help you in your power transformer sizing, specs, and shipment.
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