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This guide indicates the terms and definitions, operating conditions, product models, basic parameters, structural requirements, and technical requirements of three-phase combined power transformers with a rated capacity of 4000KVA and above, a nominal system voltage of 110kv~500kv, and a rated frequency of 50Hz. , Nameplate, allowable deviation, inspection rules and methods, lifting, packaging, transportation, installation, and storage.
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-FIND THE BEST THREE-PHASE OVERHEAD TRANSFORMER GUIDE ON THE WEB ALL IN ONE PLACE. SEE OUR LIST OF 8+FAQ RIGHT HERE.
The three-phase site-combined power transformer refers to a three-phase site-combined power transformer that will share one oil tank and install three units on the same foundation through pipelines.
The three-phase combined power transformer is applied to the climate and environmental conditions at different altitudes, as shown in Table 1.
For transformers scheduled to be installed at a certain altitude, the environmental parameters can be negotiated between the supplier and the buyer with reference to Table 1.
| No | Environmental parameters | Altitude m | ||||||
| 0 | 1000 | 2000 | 3000 | 4000 | 5000 | |||
| 1 | Air pressure/kpa | The annual average | 101.3 | 90 | 79.5 | 70.1 | 61.7 | 54 |
| 2 | Air humidity/°C°C | lowest | 97 | 87.2 | 77.5 | 68 | 60 | 52.5 |
| Highest | 45.4 | 45.4 | 35 | 30 | 25 | 20 | ||
| Highest daily average | 35、30 | 35、30 | 25 | 20 | 15 | 10 | ||
| The annual average | 20 | 20 | 15 | 10 | 5 | 0 | ||
| lowest | （+5、-5、-15、25、-40、-45 | |||||||
| Maximum daily temperature difference/K | 15、25、30 | |||||||
| 3 | Relative humidity/% | The wettest month has the smallest monthly average (monthly average maximum temperature/°C) | 95.9 （25） | 95.9 （25） | 90 （20） | 90 （15） | 90 （10） | 90 （5） |
| The driest month has the smallest monthly average (monthly average maximum temperature/°C) | 20 （15） | 20 （15） | 15 （15） | 15 （10） | 15 （5） | 15 （0） | ||
| 4 | Absolute humidity/(g/m2) | The annual average | 11 | 7.6 | 5.3 | 3.7 | 2.7 | 1.7 |
| Annual average minimum | 3.7 | 3.2 | 2.7 | 2.2 | 1.7 | 1.3 | ||
| 5 | Maximum direct solar radiation intensity/(W/m2) | 1000 | 1000 | 1060 | 1120 | 1180 | 1250 | |
| 6 | Maximum custom/(m/s)s） | 25、30、35、40 | ||||||
| 7 | Maximum precipitation (continuous 10min)/mmmm | 15、30 | ||||||
| 8 | Maximum soil temperature (depth 1m)/°C | 30 | 25 | 20 | 20 | 15 | 15 | |
The rated capacity, voltage combination, tapping range, connection group number, no-load loss, load loss, no-load current, and short-circuit impedance of the 110kvthree-phase site-combined power transformer should meet the requirements of Table 2~Table 6.
Table 2~Table 6 are applicable to transformers with hierarchical insulation for high-voltage windings (the rated insulation level of the neutral point segment is: the RMS value of the rated applied to withstand voltage is 95kv, and the peak value of the rated lightning impulse withstand voltage is 250kv).
For step-up transformers, a tapless structure should be adopted, and taps can be set if there is a requirement for operation.
| Rated Capacity kva | Voltage combination and tapping range | Connection group label | No-load loss kW | Load loss kW | Load current% | Short-circuit impedance% | |
| High voltage kv | Low voltage kv | ||||||
| 40000 | 110±2 X 2.5% 115±2 X 2.5% 121±2 X 2.5% | 6.3 6.3 10.5 | YNd11 | 33 | 148 | 0.45 | 10.5 |
| 50000 | 39 | 175 | 0.42 | ||||
| 63000 | 46 | 208 | 0.38 | ||||
| 75000 | 13.8 15.75 18 21 | 52 | 238 | 0.33 | 12~14 | ||
| 90000 | 60 | 273 | 0.3 | ||||
| 120000 | 76 | 339 | 0.27 | ||||
| 150000 | 88 | 401 | 0.24 | ||||
| 180000 | 100 | 460 | 0.2 | ||||
The capacity of the high, medium, and low voltage windings are allocated as (100/100/100)%.
According to user needs, the medium voltage can choose a voltage value different from that in the table, and the capacity exceeds 90000kva. It is not suitable to set up taps for medium voltage.
For step-up transformers, a tapless structure should be adopted, and taps can be set if there is a requirement for operation.
| Rated Capacity kva | Voltage combination and tapping range | Connection group label | No-load loss kW | Load loss kW | Load current% | ||
| High voltage kv | Medium voltage kv | Low voltage kv | |||||
| 40000 | 110±2 X 2.5% 115±2 X 2.5% 121±2 X 2.5% | 36 37 38.5 | 6.3 6.3 10.5 21 | YNyn0d11 | 41 | 179 | 0.45 |
| 50000 | 48 | 213 | 0.42 | ||||
| 63000 | 56 | 256 | 0.38 | ||||
| 90000 | 74 | 335 | 0.3 | ||||
| 120000 | 92 | 416 | 0.27 | ||||
| 150000 | 109 | 492 | 0.24 | ||||
| 180000 | 125 | 565 | 0.22 | ||||
On-load tapping transformers, temporarily providing step-down structure products.
According to user requirements, other voltage combination products can be provided.
| Rated Capacity kva | Voltage combination and tapping range | Connection group label | No-load loss kW | Load loss kW | Load current% | Short-circuit impedance% | |
| High voltage kv | Low voltage kv | ||||||
| 40000 | 110±8 X 1.25% | 6.3 6.6 10.5 21 | YNd11 | 38 | 156 | 0.45 | 12~18 |
| 50000 | 44 | 194 | 0.42 | ||||
| 63000 | 52 | 232 | 0.38 | ||||
| 90000 | 68 | 304 | 0.3 | ||||
| 120000 | 85 | 378 | 0.27 | ||||
| 150000 | 100 | 447 | 0.24 | ||||
| 180000 | 116 | 513 | 0.22 | ||||
On-load tapping transformers, temporarily providing step-down structure products.
The capacity of the high, medium, and low voltage windings are allocated as (100/100/100)%.
According to user needs, the medium voltage can choose a voltage value different from that in the table or set traps, and the capacity exceeds 90000kva. Taps are not suitable for medium voltage.
| Rated Capacity kva | Voltage combination and tapping range | Connection group label | No-load loss kW | Load loss kW | Load current% | Short-circuit impedance% | ||
| High voltage kv | Medium voltage kv | Low voltage kv | ||||||
| 40000 | 110±8 X 1.25% | 36 37 38.5 | 6.3 6.3 10.5 21 | YNyn0d11 | 44 | 179 | 0.45 | high-midium 17.5~18.5 high-low 10.5 midium-low 6.5 |
| 50000 | 52 | 213 | 0.42 | |||||
| 63000 | 61 | 256 | 0.38 | |||||
| 75000 | 68 | 292 | 0.38 | |||||
| 90000 | 80 | 335 | 0.3 | |||||
| 120000 | 99 | 416 | 0.27 | |||||
| 150000 | 116 | 492 | 0.24 | |||||
| 180000 | 133 | 565 | 0.22 | |||||
For step-up transformers, a tapless structure should be adopted, and taps can be set if there is a requirement for operation.
| Rated Capacity kva | Voltage combination and tapping range | Connection group label | No-load loss kW | Load loss kW | Load current% | Short-circuit impedance% | |
| High voltage kv | Low voltage kv | ||||||
| 40000 | 110±2 X 2.5% 115±2 X 2.5% 121±2 X 2.5% | 36 37 38.5 | YNd11 | 38 | 156 | 0.45 | 10.5 |
| 50000 | 42 | 194 | 0.42 | ||||
| 63000 | 49 | 232 | 0.38 | ||||
| 75000 | 55 | 265 | 0.38 | 12~14 | |||
| 90000 | 64 | 304 | 0.3 | ||||
| 120000 | 79 | 378 | 0.27 | ||||
| 150000 | 93 | 447 | 0.24 | ||||
| 180000 | 104 | 513 | 0.22 | ||||
Three-phase power transformers should be hoisted in units.
Each unit should have a lifting device to withstand the total weight of the unit.
The body, mailbox, radiator, or cooler of each unit should be equipped with lifting devices.
The package of the disassembled components and parts of the three-phase power transformer (such as gas relay, quick-acting oil pressure relay, bushing, pressure release valve, temperature measuring device and fasteners, etc.) should be transported and stored without damage before installation. And free from dampness.
The main body of each unit and the disassembled large components (such as radiator or cooler, oil purifier and oil conservator, etc.) can be transported without packing, but it should be guaranteed not to be damaged or damp.
Three-phase power transformers are usually transported in units. The internal structure of each unit should remain unchanged relative to each other after passing through normal railways, highways, and shipping, and the fasteners should not be loosened.
The structure and location of the components and parts of the three-phase power transformer shall not hinder the transportation and fastening and positioning.
Each unit of a three-phase power transformer is usually transported without oil.
It must be filled with dry gas during transportation (the dew point is lower than -40°C), and the type of inflation must be clearly marked.
A seal test should be carried out before transportation to ensure a good seal when filled with gas at a pressure of 20kPa~30kPa.
The gas pressure in the mailbox should be maintained at a positive pressure during transportation and after reaching the site of each unit subject, and a pressure gauge should be used to monitor it.
If the transportation conditions permit, it can also be transported with oil.
Three collision recorders should be installed during transportation, and the transportation shock acceleration that each unit can withstand is 3g (monitored during transportation).
All components and parts of the three-phase power transformer (such as oil conservator, bushing, valve, radiator or cooler, etc.) should be protected from damage and moisture during transportation.
The installation base of the three-phase power transformer should be firm and flat, and the mailbox should take into account unfavorable factors such as ground subsidence and deformation.
The units of the three-phase power transformer should be combined strictly in accordance with the layout drawings provided by the manufacturer and the requirements of the installation and operation instructions.
During the installation of the three-phase power transformer, moisture-proof, dust-proof and pollution-proof work should be done well.
Each unit of the three-phase power transformer is divided into temporarily not installed storage and temporarily not put into operation storage after installation.
When not installed, the gas pressure in the tank of each unit should be monitored regularly. Ensure that the gas is not less than 10kPa. Protect all components and parts of the three-phase power transformer from damage and moisture.
When not put into operation after installation. The moisture absorber of the oil conservator should be installed in time after the vacuum oil filling (the oil conservator that does not need a moisture absorber should be sealed with all flanges).
This can prevent the three-phase power transformer from getting wet, and the oil level should be monitored regularly.
When you need to find more than just existing transformers, Daelim’s Transformer Service Center can help you design and produce distribution transformers that meet your unique needs.
We have our own factory and a professional team of engineers, which can design and modify application requirements that meet all your conditions.
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