P ri n ce Mo h a m m a d B in Fa h d Un i ve rs i t y
College of Engineering
Department of Electrical Engineering
Internship progress Report # 3
at
the Saudi Transformers company limited
Reporting Period:
[07July 2012 – 18 July 2012]
Submitted by:
[Abdullah Tarief Rasheed]
[200900813]
[submission date 28/7/2012]
Electrical Engineering Department
Summer 2012
Summary:
As a summery for the work in the last two weeks [23 June 2012 – 04 July 2012], here is a
brief explanation about the progress achieved and its effect upon schedule.
According to my schedule I was asked to know the nature of work in the cc-04 and cc-06T. in
cc-04 -which is the metal parts fabrication- I learned how the drawings are made for every
piece of the tank. There are very exact values to be followed. I also knew how the material is
prepared, and also I saw the welding process.
After that, I went to one of the most sections I was interested in which is the tanking section.
I knew and understood the operation in tanking, active part preparation activities, tank
preparation and tanking, vacuum oil filing chamber and system, low and high voltage
external connection, leak test under pressure, and finally transformer finalization for routine
testing.
In fact, there were a lot of tasks in the tanking section, and I could understand many things
that were not clear before. I also was taught many things I learned in my electrical
engineering classes especially in the three-phase connection. Before I explain what I learned
practically about the three phase transformer, let me define it first.
Three-phase transformer units are designed to be installed as a complete unit. Instead of
installing three individual transformers & field-connecting them into the desired pattern, a
transformer (pre-assembled as a unit) is used. The transformer windings are assembled on a
common core & the appropriate leads are brought out. There are usually three high-voltage
leads marked H1-H2-H3. The secondary leads would be marked X1-X2-X3. In three-phase
transformers the phase rotation or phase sequence, is critical between the primary & the
secondary.
A three-phase transformer wound on a common core offers advantages over a bank of
single-phase transformers. A three-phase transformer wound on a common core is lighter,
smaller and cheaper than the bank of three single-phase transformers. The common core
three-phase transformer also requires much less external wiring than the bank of singlephase transformers and can typically achieve a higher efficiency. The bank of three singlephase transformers does offer the advantage of flexibility. In the case of an unbalanced load,
one or more transformer in the bank can be replaced by a larger or smaller kVA-rated
transformer.
In terms of maintenance, a malfunctioning transformer in the bank of transformers can be
easily replaced while the entire common core three phase transformer would require
replacement. I also l earned how these three phase are connected using wye and delta
connection method. I learned this comprehensively in circuits2 and I saw it in STC factory.
On the other hand, there are many things I've learned beside the production process. One of
them is the importance of team work and how the work is divided among the workers.
Understand of the human resources is clearly seen in the industries.
Background :
In the previous two weeks [07July 2012 – 18 July 2012] and according to the training
program I understood the nature of the work in cc-06f (final assembly).
This section is very important because after the active part of the transformer is places
inside the tank and the connections are made and the test bay is dome, it is important to
prepare the transformer to the final position and make sure that it is ready to be used.
Progress:
1. Planed work:
The planed work in these two weeks was to learn everything in the final assembly including:
preparing the transformer for the final position and fixing accessories as per drawing
required.
2. Work done:
Here is a detailed description of what I learned in these two weeks:
Now we come to the last section in production department in STC which is called final
assembly (cc-06f). The nature of work in the final assembly can be summarized in three main
points: painting, final assembly, and lettering and marking.
After the test bay - (this task is related to quality department not to production and that’s
why it was not mentioned previously)-the transformer is sprayed with specified color. This is
for painting.
For final assembly, the workers assemble the busing with active horns and all needed
accessories. They also fix the electrical wiring and terminal box as well as the earthing
terminals. This is also including touching up paining for all transformer accessories, final leak
testing, preparing and fixing rating plate/STS logo, fixing the pallet and finally making crate
for shipment.
Final task in cc-06f is lettering and marking. They apply paint on engraved phase marking, fit
cable box, fix circuit breaker, and connect LV stems to the circuit breaker by means of
copper connection bars if required.
3. Problems:
One of the problems that I have faced is that, sometimes I could not understand something
in a section until I moved to the next one. This is because the production process in the
sections is strongly related. As I moved to the next sections I could understand better.
4. Schedule:
The schedule for is to continue training in the same section (final assembly).
Plans:
Next week I will continue working to cc-06F, I will go back to all previous sections for the
general review, and I will look at the drawings and designs. I am planning also to try to know
the theories and the formulas for every process made.