The S11-400KVA oil-immersed transformer is assembled using oriented high-permeability silicon steel sheets. The core is a wound core type with fully mitered stacked lamination, and the core columns are of multi-step circular cross-section, ensuring low noise and low loss. The tank structure is robust, with high and low voltage cable boxes welded on both sides for cable connection. The high-voltage winding is equipped with a tap voltage of ±5% of the rated voltage, and a tap changer is used to change the voltage. The power must be cut off before switching, and the protective cover of the tap changer on the tank wall must be removed to perform the voltage change. The low-voltage side of the transformer allows “Y” connection for 693V or “D” connection for 400V power supply. Six porcelain bushings are directly installed in the cable junction box, with secondary terminals for users to modify the connection. The transformer is lifted using lifting lugs welded to the tank wall. The transformer base is equipped with skids, which have mounting holes for adding mining wheels when required in mining applications.
Application Range of S11-400KVA Oil-Immersed Transformer
Suitable for oil-immersed mining power transformers with a capacity of 1250A or less and a voltage of 10KV or less. This type of mining transformer is a general-purpose oil-immersed transformer without explosion-proof requirements. It is mainly used as a power source for mining lighting or electric drives during mine power distribution. After transportation, these series transformers do not require core inspection and can be assembled with relevant disassembled components. Therefore, acceptance test items are specified accordingly.
Standards Followed by S11-400KVA Oil-Immersed Transformer
The S11-400KVA oil-immersed transformer complies with the following standards:
GB1094.1~2-1996, GB1094.3,5-2003, GBT6451-2008, GB12173-2008.
Operating Environment and Working Conditions of S11-400KVA Oil-Immersed Transformer
1. Altitude not exceeding 1000m above sea level; special conditions require separate clarification.
2. Ambient temperature:
· Maximum air temperature: +40℃;
· Maximum daily average temperature: +25℃;
· Maximum annual average temperature: +20℃;
· Minimum outdoor air temperature: -20℃.
3. Relative humidity of surrounding air not exceeding 95% (at +25℃);
4. Installed in underground mines where coal dust and gas are present but without explosion hazards;
5. The waveform of the power supply voltage approximates a sine wave.
Selection Principles for S11-400KVA Oil-Immersed Transformer
The selection of capacity for the S11-400KVA oil-immersed transformer is a comprehensive and complex technical issue that cannot be expressed by a simple formula. The selection of transformer capacity is related to factors such as load type and characteristics, load factor, demand factor, power factor, active and reactive losses of the transformer, electricity price (including basic electricity price), infrastructure investment (including transformer price, installation and civil engineering costs, and power supply connection fees), service life, transformer depreciation, maintenance costs, and future plans.
The basic estimation of capacity for the S11-400KVA oil-immersed transformer mainly includes the following aspects:
1. Estimation Using the Calculated Load Method
First, determine the total calculated load to be supplied by the transformer, then estimate using the following formula:
Total transformer capacity = Total calculated load + Margin for future capacity expansion.
2. Estimation Using the Economic Operation Efficiency Method
The selected transformer should have its economic load equal to or close to the actual operating load, i.e., transformer capacity ≈ S / βm, where S is the actual operating load (VA), and β is the load factor at which the selected transformer achieves high efficiency.
Construction Features
The core (windings and core) of the S11-400KVA oil-immersed transformer is housed in an oil-filled tank made of welded steel plates. Medium and small transformers have a tank consisting of a tank body and a cover. The core is placed inside the tank, and removing the cover allows the core to be lifted out for maintenance. The S11-400KVA oil-immersed transformer uses imported silicon steel sheets to ensure core performance, high-quality red copper electromagnetic wire, and electrical-grade insulating pressed wood. For capacities ranging from 630 to 2000kVA, the low-voltage windings adopt a cylindrical or helical structure, ensuring balanced ampere-turn distribution, strong short-circuit withstand capability, no deformation, no bursting, and high mechanical strength.
