The document discusses a presentation on innovations in air cooled 3 phase transformer design by Michael Larkin of Tortech Pty Ltd. The presentation will cover Tortech's research on IP56 stainless steel enclosures for 3 phase transformers used by NSW State Railways. It will also discuss their solar isolation transformer design that improves efficiency and temperature characteristics. The talk will review calculations for temperature rise in enclosed transformers, the use of different core materials, IP56 enclosure design, solutions for in rush current, and aluminum windings in air cooled transformers.

1. Innovations in Power Efficiency: The Design of Air Cooled 3
Phase Transformers
Joint Electrical Institutions Sydney - Engineers Australia, IEEE, IET
DATE & TIME
Thursday, 10 September, 2015
5:30 pm for 6:00 pm start
VENUE
Engineers Australia Harricks Auditorium
Ground Floor, 8 Thomas Street, Chatswood NSW 2067
COST
EA, IET, IEEE Members –
Complimentary
Students – Complimentary
Non-members - $30
CPD
Eligible for 1.5 Continuing Professional Development
hours.
RSVP
HOSTED BY
Joint Electrical Institutions Sydney
Presentation by Michael Larkin - Managing Director of Tortech Pty Ltd and
Tortech Lighting Pty Ltd
The design of 3 phase transformers has been standard for some years. However, with the
introduction of new magnetic material and the ever increasing demand for power efficiency,
we are constantly developing new designs to meet these efficiency requirements.
Recently our team at Tortech has researched IP56 3 phase transformer design for the NSW
State Railway using special stainless steel enclosures. We have successfully overcome the
problem of high temperature failures by using air cooled transformers. The solution is in using
thermodynamic principles incorporated in with the Electrical transformer design.
In addition, our Solar Isolation Transformer Design incorporates the perfect solution for
minimising the core losses, and thereby improves the efficiency and temperature characteristics
of the enclosed transformer. This has enabled the Solar Inverters to operate more efficiently
and provide substantial cost savings to the customer.
The talk will review some of Tortech’s R & D research areas including:
1) Calculation of temperature rise of enclosed 3 phase air cooled
transformers
2) Use of different core steel characteristics based on application
3) Design of IP56 stainless steel enclosures for 3 phase
transformers
4) The solution for the problem of “in rush” current for railway
applications
5) The use of aluminium windings in air cooled
transformers
This talk will review the innovation in winding techniques and cooling calculations that have
been developed recently for the major industry applications in Mining, Railway, Transport and
SolarPower.
The talk will be stimulating and interesting to both the experienced engineers and those
new to the workplace.

2. 2

3. 1. 1975-1984: Power Transformer Designer at Tyree
Westinghouse at Moore Bank, NSW
 Specialised in Current and Instrument Transformer
Design, including high voltage 500 KV CT, 500 KV
CVT, Line traps and magnetic voltage transformers.
2. 1985-1987: Power Transformer Designer at Ferguson
Transformers at Moore Bank, NSW
 Specialised in three phase transformers and control
gear for HID equipment, including lighting control
design for Western Australia Cricket ground and
MCG.
3. 1987-Present: Established two companies: Tortech Pty Ltd
and Tortech Lighting Pty Ltd at Greenacre, NSW.
 We Quote, Design, Manufacture, Test and organise
approvals for transformers, lighting, Inverters,
Inductors, etc.
 We import and export both in Australia and overseas
to countries such as Indonesia, Malaysia, Brazil,
China, New Zealand 3

4. • Calculation of the temperature rise of air cooled
Transformers
• The use of a variety of core and conductor
material
• The design of transformers in IP23 Indoor & IP55
Outdoor enclosures
• Design challenges for Railway & PV centralised
MV Transformer applications
• Resin encapsulated F1 fire retardant class
transformers
4

5. To expose engineers to new design techniques using
alternative materials
• What are the main parameters of any
transformer quotation?
 Design / Price / Availability / Application
• How do we get the best for our client?
• “Build with the End in mind”
Rationale
To improve the competitiveness and efficiency of the
transformers and to meet customer requirements in a
competitive global market.
5

6.  Let’s explore the 4 main considerations for 3 Phase transformers:
1. The design of a conventional 3 phase transformer
• The use of Non-Grain stacked cores
• Design parameters – Non-grain steel has low remanence flux
density
• Applications e.g NSW Railways, QLD Railways, PV Panels for
Solar Power
• Underlying principles and design parameters – especially for
Railway to limit in rush current to less than 10 times the rated
current/turns on current.
• Winding techniques to modify the self inductance and
resistance of the coils
• Enclosures – IP23 or IP55 – environment
• Example: Table of G.O.S.S, Non-G.O.S.S and Amophorous
Core’s
Non-Grain Stacked Core
6

7. G.O.S.S UnicoreNon-G.O.S.S Core Amorphous Core
 Design
• Choice of material
Non-G.O.S.S Core G.O.S.S Unicore Amorphous Core
Low Remanence Flux density High Remanence Flux density Moderate Remanence Flux density
Cheapest in Cost Reasonably Expensive Expensive
High loss: Watts/Kg Low loss: Watts/Kg Very Low loss: Watts/Kg
Suitable for Rail applications which Suitable for Solar PV installations which *G.O.S.S=Grain Oriented Silicon Steel7

8. Non-G.O.S.S G.O.S.S Amorphous
Saturation
Flux Density
1.5 Tesla 1.8 Tesla 1.5 Tesla
Remanence 1 Tesla 1.7 Tesla <0.5 Tesla
Core Loss
(50Hz)
2 W/Kg 1.1 W/Kg <0.2W/Kg
8

9. OPTION (A) Aluminium Windings and Sheet
Advantages Disadvantages
• Extremely Cheap • Higher Loss than Copper
• Not readily Available
OPTION (D) Aluminium Rectangular Conductor
Advantages Disadvantages
• Extremely Cheap • Higher Loss than Copper
• Not readily Available
OPTION (C) Copper Sheet
Advantages Disadvantages
• Low Loss • Highly Expensive
• Not readily Available
OPTION (B) Copper Rectangular Conductor
Advantages Disadvantages
• Low Loss
• Readily Available
• Highly Expensive
9

10.  When Analysing a design with a customer we look for:
1)
2)
3)
• Do you require off load Tap changer switches on the transformer?
• Do you require a screen and why do you require a screen?
Working
Environment
Ambient
Temp.
OutdoorIndoor
IP22 IP23 IP55 IP67 Is it 30˚C Is it 50˚C
What is the type of protection used?
D-Curve BreakerC-Curve Breaker
Installation
Lifting Lugs?Bushings?Access
Points?
Cable Entry?
10

11.  Specially designed core and coils have reduced induction
levels, resulting in a reduction in stray losses.
 Electrostatic shield reduces transient noise in the system which
may affect sensitive computer loads.
 Reduced core flux density prevents core from saturation and
overheating from voltage distortions caused by harmonic
currents.
 High Grade, Non-aging, silicon steel with high magnetic
permeability provides core induction levels without saturation.
 Neutral bus sized and configured to accommodate at least
200% of the rated currents compensates for increased neutral
currents found in non-linear loads, thus reducing heat.
 This is caused by harmonics in the input supply current. 11

12. 3-Phase’s
Air Ducts in
each phase
G.O.S.S Core
Flux Density at 1.55
Tesla,
Star IN–Delta OUT
12

13.  Aluminium-Copper
Welding through Electrofusion
13

14. Sources: Michael, A.
Afflerbach 2005, Solar
Atmospheres
Manufacturing, Inc, IEEE,
Indianapolis, IN
14

15. ∆TC =
𝑳𝒐𝒔𝒔
[ K 𝒓A 𝒓 + K 𝒄A𝒄 ]
𝑳𝒐𝒔𝒔 = 𝑻𝒐𝒕𝒂𝒍 𝑳𝒐𝒔𝒔 𝒇𝒓𝒐𝒎 𝑺𝒖𝒓𝒇𝒂𝒄𝒆 𝑾
K 𝒓 = 𝑪𝒐𝒆𝒇𝒇𝒊𝒄𝒊𝒆𝒏𝒕 (𝑾/˚𝑪 𝒊𝒏 𝟐
)
A 𝒓 = 𝑹𝒂𝒅𝒊𝒂𝒕𝒊𝒐𝒏 𝑨𝒓𝒆𝒂 𝒊𝒏 𝟐
A 𝒄 = 𝑪𝒐𝒏𝒗𝒆𝒄𝒕𝒊𝒐𝒏 𝑨𝒓𝒆𝒂 𝒊𝒏 𝟐
K 𝒄 = 𝑪𝒐𝒆𝒇𝒇𝒊𝒄𝒊𝒆𝒏𝒕 (𝑾/˚𝑪 𝒊𝒏 𝟐
)
 Electrical Equivalent Circuit
15
Sources: Calculation of the
temperature rise A thesis by Walter
Johnson June 1942 . PA State
College

16.  Electrical Equivalent Circuit
16
Sources: Calculation of the
temperature rise A thesis by Walter
Johnson June 1942 . PA State
College

17. Sources: Michael, A.
Afflerbach 2005, Solar
Atmospheres
Manufacturing, Inc, IEEE,
Indianapolis, IN
 Un-Ducted
Design
17

18. Sources: Michael, A.
Afflerbach 2005, Solar
Atmospheres
Manufacturing, Inc, IEEE,
Indianapolis, IN
 End Ducted
Design
18

19. Sources: Michael, A.
Afflerbach 2005, Solar
Atmospheres
Manufacturing, Inc, IEEE,
Indianapolis, IN
 Full Ducted
Design
19

20. Sources: Michael, A.
Afflerbach 2005, Solar
Atmospheres
Manufacturing, Inc, IEEE,
Indianapolis, IN 20

21.  Overall Design
Core Loss:
785.65
Flux Density
1.55 Tesla
Temperature
Rise: 70˚C
Half Duct-
Half way
through
the HV
Half Duct-Half way
through the LV
Full Duct
between LV
and HV
Full Duct-Half
way through
the LV
21

22. 1. No HV
Intermediate Duct
2. No LV Intermediate
Duct 3. No HV and LV
Intermediate Ducts
Increase in
Temperature
Rise to 105˚C
Increase in
Temperature
Rise to 175˚C
Temperature
Rise
Stays at
175˚C 22

23. Increase in
Conductor
Size
High in
Temperature Rise
159˚C
 Having Removed all ducts with increased conductor size on
primary Winding
23

24.  Half & Full Ducts:
Dog-Bones
Half Ducts
Full Ducts
 How the ducts are Wound:
24

25.  Natural Air Currents near Heated Plate
Heated Plate
Duct Width Restriction Factor
(Fr)
Over 1/2” 1.00
3/8” 0.75
1/4” 0.50
25
Reference: A thesis by Walter
Johnson June 1942 . PA State
College

26. To allow Air Flow, Notice the
bend in Bus bar
26

27.  Final Product
27

28.  Dry-Type
25 KVA Transformer:
28

29. Taps on
each Phase Resin Encapsulated Transformers:
Cross flow fans 29

30. 30

31. 31

32. Shiny Stainless
Steel Grade
304 Material
Inside wall
painted Matt
black
Top Sun
Shield
enclosing the
Transformer
Large Vents at
Bottom of the
enclosure
Large Vents at
Top of the
enclosure
To allow for
Air Flow
32

33. Electrostatic
Shield Earth
connections
33

34. Temperature
Rise 71˚C
34

35. 35
 IP55 Stainless Steel Enclosure

36. *EN = Enclosure
36

37.  These are some of the questions you have to ask your
customer:
• What duty cycle do you have?
 Is it 20%, 50% or 100% duty cycle
• Is the customer looking for a transformer that has a low loss or
a high loss?
• Are they interested in a transformer that costs less but has a
high operating costs?
• What K-Factor do you need?
• What is your required temperature rise
• What is your Ambient Temperature requirements
37

38.  The Design of a three-Phase Dry type transformer is
one of the most difficult designs to do as one must
consider the inside and outside performance.
 The communication with the client is essential as the
engineer must investigate all parameters of the
client’s requirements, helping him/her to understand
the ramification of they’re requirements. So the end
product will be appreciated by the client – Job
Satisfaction is highly vital (for both the customer and
the Designer).
 We want to get the job right the first time around.
38

39. 39