66 KV Oil Immersed Power Transformer For Industrial Factory GB1094.5-2003

66 KV Oil Immersed Power Transformer For Industrial Factory GB1094.5-2003

Description:

The 66KV transformer is based upon world-wide advanced technology and also incorporates the experiences of internationally leading transformer companies as well as our own long-term experiences. Low loss, low partial discharge and high short circuit withstand capability series transformers are achieved through innovation and optimization. Our transformer conform entirely with latest national standard GB1094.1~2-1996, GB1094.3-2003, GB1094.5-2003 and international standard IEC-76. Outstanding features as follows:

1. Low loss, low noise

The core laminations are composed of imported high quality grain-oriented cold-rolled silicon steel sheets with chamfered joints and the joints are step-lapped with 5 steps, thus ensuring low loss and low noise. The inside of the tank is lined with magnetic and copper shields, measures have been take for metallic structural pares located in high magnetic field, to deduce stray loss and thereby the total load loss, and to relieve local overhearing.

2. Safe and reliable service

Reliability is the everlasting objective of our company, partial discharge of finished products are constantly kept below 100pC, ensuring that the transformers can be operated under long service voltage and occasional over-voltage without trouble. Low current density in winding conductor and appropriate cooling arrangement ensure that the winding temperature rise and top oil temperature rise are lower than that specified in the national standard by more than 5K and that the mechanical stress in winding conductor during short circuit does not exceed certain safe limit. Together with technological procedures during manufacture and other means to elevate mechanical strength, transformers can withstand server short circuit in all case during service.

3. Easy erection and maintenance

To minimize erection work at sit, transformers are so fabricated that lifting the active part out of the tank for inspection after arrival at sit is not mandatory. Beside, all components to be mounted on the transformer at site have been preassembled before dispatch, and all secondary wirings have been laid down into conduits on the transformer and connected to the terminals in the control cabinet or terminal box.

4. Careful fabrication

Vertical winding machines with tension device are used for winding, so that the windings can be wound more tightly and therefore mechanically strength as a whole. All insulation parts subjected to mechanical stress during short circuit, such as spacers in windings are made with T4 demystified pressboard to deduce shrinkage. Drying process for the windings are carried out twice, once for ht individual winding, and again for the assembled phase block.  After core and coil assembly, an additional vapor phase drying (VPD) is once more carried out to ensure that all insulation parts are thoroughly dried and no further shrinkage is possible to occur during service. All the high voltage terminals and nearby metallic structural parts are rounded up to prevent partial discharge. High voltage bushing terminals are contained with turrets, and kept concentric with the turret. All the leads are properly crimped and metallized to be rounded up. VPD process insures that the moisture content within the transformer is kept at a very low level, and the core and coil assembly is once more cleaned by condensed vapor flowing down the surfaces. The fabricated tanks are relived from welding stress and shot-blasted integrally, so as to be free form oil leakage trouble and to give the tank a clean, pleasant looking appearance.

The following outstanding features:

1. Low loss, and significantly energy-saving. The average no-load loss is 35% lower than prescribed by National Standard GB/T 6451-2008.

2. The core laminations are made up from high-quality cold-rolled grain-oriented silicon steel sheets with chamfered joints and without punched holes, and are stacked without the upper yoke sheets in place, so that they are effectively improved no-load upper together with lower frame.

3. Zigzag directed flow of oil are provided within the windings, so that all parts of the windings can be cooled more evenly.

4. The regulating winding is a separate winding which apart from the high voltage main winding. In this way, total ampere-turn balance between windings ; and the axial electrodynamics force during short circuit can be  reduced, thus upgrading the short circuit withstand capability of the transformer as a whole.

5. The windings of one phase are assembled into an integral phase block before placing into the core.

6. The winding manufacture, winding assembly core and win