500KVTRANSFORM

Brief Introduction to Products
1. Structure characteristics of 500kV power transformer
Winding
The interleaved structure or shieldinginserted structure is adopted in
the winding of 500kV and above transformer. Transposed and multiple
conductor is used to improve the impulse voltage distribution and reduce
the additional losses of winding effectively. The electrical field and
impulse characteristic of winding are calculated by computer program to
guarantee the excellent electrical characteristics and impulse strength
of winding. The winding for large transformer is wounded by vertical
winding machine to achieve a tight and reliable winding. The edges of
rib and spacer in winding have been rounded to improve the dielectric
strength.
Core
The core is made of imported high quality cold-rolled grain-oriented
silicon steel. The core adopted full-bevel joint structure of 45° with
silicon steel out of punching hole to reduce the no-load losses of
transformer. All silicon steels are cut by advanced cutting machine
imported from George Company with the height of burrs less than 0.02mm.
The limb and side limb are fastened by polyester fiberglass glued band
without woof. The top and bottom yokes are tightened by the fiberglass
glued band through the tightening frame assembled on the clamp. For the
large transformer, the top & bottom yokes are connected with core firmly
by the non-magnetic steel flitch plate at both sides of core limb to
form a rigid steel frame for enhancing the mechanical stability of core,
so as to improve the short-circuit withstand ability of transformer.
Active part insulation
After the drying treatment of the active part in 400kW large kerosene
vapor phase drying oven imported from Switzerland, the water content of
insulation parts can decrease to less than 0.5%. The insulation parts
and active part assembly are carried out in the dust-proof room with
air-conditioners to guarantee the PD value of transformer fulfilling the
requirement in IEC standard. The rounded treatment shall be done for
winding exit and welded area of leads. The insulation pressing plate is
used to press the active part. The whole set winding assembly
processing, i.e. assemble whole set of windings on the core at the same
time was improved to enhance the product reliability as well as shorten
the processing duration for ensuring the product quality.
Tank
Normally, the tank is designed as bell type. The steel plates for tank
wall are bent to the corrugated shape by imported large bending machine,
or the tank walls are welded with bent stiffeners to enhance tank’s
mechanical strength and decrease the number of welding seams so as to
perfect the appearance of transformer. In order to decrease the stray
losses of transformer, the magnetic shielding or combined
copper-magnetic shielding is placed on the inner surface of tank wall
for extra-large transformer. Currently, some of tank for extra-large
transformers are made of non-magnetic steel plates. The tank frame can
be sealed either by bolts or welded together with upper and lower parts
tank.
2. Product application
A. DFPFS-250000/500 single-phase off-load power transformer operating in
Liaoyang substation, Liaoning province
B. ODFPSZ-250000/500 auto-power transformer with on-load tap changer
operating in Fangshan substation, Beijing
C. SFP-300000/500 generator step-up transformer operating in Gezhouba
hydropower station
D. ODFPS-250000/500 auto-power transformer with no-load tap changer
operating in Caopu power plant, Yunnan province
E. SFP-360000/500 generator step-up transformer operating in Yantan
power plant, Guangxi Zhuang Autonomous Region
F. ODFPSZ-250000/500 auto-power transformer with on-load tap changer
operating in Yangcheng power plant, Shanxi province
G. SFP10-400000/500 generator step-up transformer operating in Guohua
Zhungeer power plant, Inner Mongolia Autonomous Region
H. SFP-160000/420 generator step-up transformer operating in Dong Ran
Electromechanical Project, Iraq
I. ODFPS-250000/500 transformer operating in Ertan Changshou substation