Product description
4000KVA oil-immersed transformer factory test items:
| Unbalance rate of winding resistance | Interline ≤2% |
| Short-circuit impedance | 4.0±5% (main tap), 4.0±15% (other tap) |
| Load loss | Po≤0.91±15% |
| No-load loss | Pn≤0.13±15% |
| No-load current | Io≤2.0±15% |
| Winding temperature rise limit | K≤65K |
| Sound power level | Less than ≤72dB(A) |
| Externally applied pressure | 35 (high pressure side), 5 (low pressure side) |
4000KVA oil-immersed transformer implementation standard:
| GB1094.1 “Power transformers – Part 1 General provisions”; |
| GB1094.2-1996 “Power transformers – Part 2 Temperature rise”; |
| GB1094.3-2003 Power transformers – Part 3 Insulation level, insulation test and air gap for external insulation |
| GB1094.4-2003 Power transformers – Part 10 Sound level identification |
| GB/T6451-2008 “Technical Parameters and Requirements for Oil-Immersed Transactors” and entrustment requirements |
| GB1094.5-2003 |
| GB/T15164 “Load Guidelines for Oil-Immersed Power Transformers” |
| IEC76 Power Transformers |
| GB2536 “Transformer Oil” |
4000KVA oil-immersed transformer operating conditions:
1. Altitude: H<1000m
2. Working ambient temperature: -25°C~+40°C
3. Relative humidity: when the air is +25°C, the relative humidity does not exceed 90%
4、air velocity：＜35m/s
5. Seismic acceleration: horizontal acceleration is 0.4m/s2
6. Workplace: no fire, explosion hazard, chemical corrosion level severe vibration occasions
In order to improve the short-circuit resistance of transformers, our company has adopted the following effective methods
◆ The introduction of international advanced technology fully considers the various situations when the product bears short circuit and solves it in a targeted manner, and adopts a series of measures such as rigid positioning on six sides of the body to maintain the overall stability of the product.
◆ The design adopts dynamic force calculation to assess the dynamic and thermal stability of the product; Set up a separate voltage regulating coil to strictly ensure the ampere-turn balance of the high and low coils, and at the same time maintain the consistency of the magnetic center of the high, low and voltage regulating coils, so that the short-circuit electric power is minimized;
◆ The low-voltage coil directly winds the high-strength bobbin, and the high, low, and voltage-regulating coils adopt a compression device in the radial and axial directions when winding, and the outer diameter side adopts a locking brace to increase radial firmness measures;
◆ The coil is dried by pressure vacuum, assembled as a whole, and the coil height is repeatedly adjusted during the reassembly process to ensure that the final high and low pressure coil height is completely consistent, that is, the coil is stabilized. The axial strength of the coil is improved by pre-densification of all cushion blocks, chamfering and deburring, evenly arranging the compression parts of the body to ensure mechanical strength and sufficient compression force
◆ High voltage, low voltage, voltage regulating coil winding to ensure that the geometric size of the coil itself is accurate, the assembly center between the coil and other parts of the scale of the scale of the tight, between the paper tube and the core with a brace rod solid support, coil set to adopt a series of combination technology in the spokes to bundle and solidify, and each part will not be channeled and unstable deformation when subjected to short-circuit electric power
◆ The lead wire is fixed to strengthen the encryption, and the parts adopt self-locking and anti-loosening structure to meet the dynamic and thermal stability in the event of short circuit.
◆ The radial fastening of the coil adopts the “zero” margin design, and the iron core and the low-voltage coil paper tube, between the low-voltage, high-voltage, voltage-regulating coil and between the support bar and the coaming plate are evenly and fully dried, and the close fit ensures that the whole coil has excellent tightness and concentricity.
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◆ The insulating materials are stored in strict and standardized drying and sealing at all stages of raw materials, semi-finished products and final assembly of the body to avoid uncontrollable moisture absorption, expansion and deformation and size changes, such as: insulating cardboard and post-processing cushion blocks, pressure rings, etc., all of which are sealed and stored in a special constant temperature drying cylinder.
◆ After the drying of the body is completed, it is strictly followed by the exposure time in the atmosphere to avoid the expansion and deformation of the insulator absorbing a large amount of water.
After taking the above measures, the transformer’s anti-short-circuit ability has been greatly improved, and it has passed the short-circuit test of the National Testing Center at one time.
