The calculating Hot-point Temperature-rise of Transformer Windings
Tang Yan, Hao Zhongyan
Shenyang Transformer Works
Shenyang 110025, China
based the conservative equations and can calculats the
Winding is an important Winding Temperature
flow and temperature distribution in windings (0liver
Indicator (WTI), but it's a difficulty calculation in design
1980,Duval 1982,Gobec 1992 etc.). However the
also. On the "porous" medium value method of
model is established with the network of hydraulics,
calculating large scale boiler and the reactor hot conduct
they flow out and temperature the majority in model
of Atomic energy to calculate flow and temperature field
condition for the complex oil in transformer windings
of Transformer Winding, the new method estimation a
to describe ability limited.
We makes extensive use of the " porous
hotspot temperature-rise of the Transformer Winding.
The experiment make extensive use of the I t porous
"technique from the continuity equation of enargy
"technique on Transformer Winding model is effective,
conservation, momentum and mass to calculate the
so pads for calculating to exceed the hotspot
technical oil in transformer winding to flow and
temperature distribution to calculate and reach the
temperature-rise of the Transformer Winding's of high
Abstract-The hotspot temperature-rise of Transformer
capacity to decide foundation.
Keyword-TransformerWinding; hotspot temperature-rise;
calculation; test.
Nomenclature:
0
Y
P
U
percent of f l u i d s i n u n i t volume
pertdbility
density
fluids velocity
hotspot temperature-rise of designer's solicitude.
11. DESCRIPTION
OF EXPERIMENTS
To seek new calculation method, we have ma'de a
set of transformer coil model, Fig.] is in which one
that special research the temperature distribution in
transformer winding coil.
r
Diffusion Coefficient
or Mass ,or Velocity ,or Temperature
S
or Friction ,or Volumetrically heat
generation rate.
9
I.
r2
INTRODUCTION
The heat generation density of modem large
Transformer is increased markedly .In order to
increase the effectiveness of heat transfer, the
Transformer Winding are divided into several pass
with baffle plates, which make the conductor discs to
4
--
I
I
I
I
7
-
-I-
be cooled by forced-detected oil. However oil flow
and heat transfer very complex in this type of the coil
winding's structure. The hotspot temperature-rise of
transformer winding's whether it is to exceed in the
mark temperature, is to measure coil winding very
important in a design. So far several sophisticated
numerical models have been proposed, which are
1
/--
Fig. 1 1 Duct 2 Box 3 Preprocess section
4 Disc 5 Inlet 6 Outlet
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considered a fluid as flow in I‘ porous medium. The
solid in transfornier winding, disc and baf€le plate etc
regard as certain kind “porous” medium, will fluid oil
flow to regard as in “porous” medium to flow in the
coil winding.
I‘
The esperinient is conducted an oil loop .The
transformer 011 from the pump is heated by a preheat r,
F
and then flows upward through the test section After
cooling by a cooler, it pass a turbine flowmeter , it’s
rate is measured. The test sections include three pass
with heating only in the central one (in Fig.1) .The
heated pass consists of 19 coils connected in series.
Between them the thickness is 7.9mm and they length
is 194mm .It is simulated transformer windings and
thermally insulated with fibre 48 thermocouples are
embeded in conductor beneath or between the
horizontal spacers to measure the temperature
distribution in the coils. An auxiliary heater is
div(aypuq5)= div(aFgradq5)+ S(1)
The oil flow is respectively processed the percent
of volume “porous “and permeability in every
direction of space. In which, permeability is a test
experience number that decided from the condition
such as transformer winding design, technology and
material. Porous is the function, with consideration the
solid Merence such as the disc in coil winding is
arranged the influence that produce. Foundation on
above-mentioned work we establish the heat conducts
equation in the disc. The equation of mass, momentum
and energy conservation may be expressed
We makes use of SIMPLE (Semi-Implicit
Method Press linked Equations) (VS.Patankar et
al.1978) technique, become above the equation of
mass, momentum etc to difference equations. In which
equation difference grids (local) see Fig.2:
equipped in it to compensate the heat loss to the
surrounding .The clamps are connected to a DC supply
for heat generation of the winding. The measured
parameters are the flow rate, the temperature in each
coil, the inlet and outlet oil temperature in a pass.
All dates were scanned and processed by a computer.
Table 1 is a group of data that gets though this
experiment.
Table, 1.
No
P(kw)
Q(mA3/h)
Tinlet(%)
Ta(K).
Th(K)
Ta’(K)
Th’(K)
No
P(kw)
Q(mA3h)
Tinlet(%)
Ta(K).
Th(K)
Ta’(K)
Th’(K)
1
2.12
0.76
49.2
16.6
22.8
17.1
21.5
5
3.0
0.55
62.7
22.7
44.1
23.5
42.7
2
2.0
2.12
62.7
12.8
15.8
12.5
16.6
6
3.0
2.9
61.1
17.8
22.3
17.1
24.2
3
3.0
2.12
63.1
18.1
22.2
18.1
24.8
7
1.6
0.76
59.5
12.7
18.0
12.4
16.7
4
4.11
2.12
61.3
23.9
31.5
24
33.2
Fig. 2 a Werence grid (local)
Under the foundation of mentioned work, we are
established a heat conduction equation for every disc
of coil winding, its boundary condition is the fluid
equation that has been calculated thermoviscous fluids
of ” porous medium.
In which, Tinlet is a temperature of inlet; Ta is
average winding temperature rise over oil; Th is
hot-spot winding temperature rise over oil ,had been
measured; Ta’ is average temperature rise; Th’ is
hot-spot temperature rise ,had been calculated.
I’
IV. CONCLUSION:
The variation of winding temperature rises over
111. BRIEFDESCRIPTION
OF THE MODEL
oil with disc number and turns in different discs as
show the Fig.3. And our calculation result basically is
trended to experimental results.
Fig. 1 is a model about transformer coil winding
by OD. Transformer oil is following fiom inlet to
outlet. This structure of coil winding had been
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used to measure temperature in high voltage
P=3 (kW)
environments. Specifically, it can be used to improve
transformer thernial design, for it allows temperatures
in hottest regions of transformers to measured. Are
doing the contrast work of our calculation method and
experiment of Optical Fiber Thermometry to measure
in passed few years, see Table 2.
The Transformer Winding does not be strict a
1
e3kV
30
network of water pipe, Transformer oil permeability is
r
stronger, in conductor of Transformer Winding the
25 -
heat can be tmsferred out through the oil. So,
20. -
traditional method has been a limitation; and some of
15 -
Type of Cooling that OFAF, ONAN etc can not been
10 -
I
0
5
10
’
15
20
25
30
calculated. Our
Turns (N)
have
considered the
permeability of oil, so it’s approached to test result;
Fig.3 The variation of mean winding coil temperature
rise with disc number and turns in Werent discs.
Our method can calculate the Transformer Winding
with different Type of Cooling without difficulty, l~nly
need be to change boundary condition.
Table 2.
\
method
w e
kV
Cooling ODAF
3ptical tYPe
kV
OFAF
REFERENCES
kV
ONAF
111
Hotspot 28.86) 23.46) 29.66)
%er
temp.-ria
n w e e Over oil
Average 19.36) 14.3(K) 21.2F)
temp.-ris
e over oil
Hotspot 31.26) 26.4(K) 28.w)
Salculati temp.
-rise
In
Over oil
Average 19.6(K) 17.I&) 20.46)
temp.-ris
e over oil
Yuzhou Chen , et al .YanTang ..., 1997.6.16-19.
In CuangZhou of China, “An investigation of hear
transfer chmcteristics in windings for the
transformers with forced-directed oil” The Second
International Symposium on Heat Transfer
Enhancement and Energy Conservation.
[2] M.Duva1, J.Aubin et al., 1982,”OiI additives for
the evaluation of hot spot temperature in Power
Transformers During Overload Tests ”,lEEE
Tms.EI-l7(5),4 14-422.
[3] Z.Godec and RSarunac,1992,”Steady-Slate
Temperature Rise of ONAN/ONAF/OFAF
Transformers”,IEE,Proc. ,C,Vol. 139,No.5,44845.
111
Optical Fiber Thermometry technology in widely
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[1] Jiang Fan et al., 1994,”An Eqerimental Study on
the distribution of flow in the forced directed
windings”, CIAE repot (in Chinese).
[7] O.Szpir0,P.H.G.AlleandC.W.Richards,
[5] A.J.Oliver, 1980,”Estimation of Transformer
Winding Temperatures and Coolant Flows Using
a General Network Method”, IEE Proc.C, Vol. 134,
No.4, 306-312.
[6] R.Sarunac, 1989,”Numerical Calculation of
Winding Temperature and Coolant Flows in
Power Transfornier with ODAF Tjye of Cooling”,
Proc. 6th Int. Conf. On Numerical Methods in
Thermal Problems Swansea, UK, 1644-1654.
1982,”Cooling Distribution in Disc Type
Transformer Winding Horizontal Dwts and Its
Influence on Coil Temperature”,proc.7th Int .Heat
Transfer Conf.,Munchen,HX16,251-256
[8] S.V. Patankar, ”A numerical method for conduction
in composite material , flow in irregular
geometries and conjugate heat transfer” ,Int., Heat
Transfer Conference, Torento, Vo1.3, p297, 1978
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