Classification of transformer
Core Coil Assembly (CCA)
3. COMPANY INTRODUCTION
“Danish Private Limited” is established in 1985 and is today
India’s leading quality manufacturer
Company Works in the field of Manufacturing and Exporting
of Transformers and Relay Panels.
Product Generated by Company:
o Distribution Transformer
o Dry type Transformer
o Power Transformer
o CRP and Substation Automation
o Substations Projects
A transformer is a device that changes ac electric power at one
voltage level to ac electric power at another voltage level
through the action of a magnetic field.
It can be either to step-up or step down the voltage.
A transformer is a static device.
The word ‘transformer’ comes form the word ‘transform’.
Transformers work on the principle of mutual induction.
“when the two coils are inductively coupled and if the current
in coil change uniformly then the e.m.f. induced in the other
coils. This e.m.f can drive a current when a closed path is
provide to it.”
“The principle of mutual Induction
states that an e.m.f. is induced in a
coil when current in the neighbouring
7. It consists of an iron core on which two separate coils of insulated
copper wire are wound.
The function of the core is to transfer the changing magnetic flux
from the primary coil to the secondary coil
The Secondary Coil has a load resistance connected to safe
transformer from being heating up.
Construction of a simple transformer
Can be seen in Fig.
8. Winding Construction
Core & Winding(Coil) Assembly
Tapping &Tap Changer
Tanking & Final Fitting
Fittings & Accessories
9. CONSTRUCTION OF WINDING
Conducting material is used for construction of winding.
The coils are used are wound on the limbs and insulated from
The two different windings are wounds on two different limbs.
The leakage flux increases which affects the performance and
efficiency of transformer.
To reduce the leakage flux it is necessary that the windings
should be very close to each other to have high mutual
11. CORE TYPE CONSTRUCTION
In this one magnetic circuit and cylindrical coils are used.
Normally L and T shaped laminations are used.
Commonly primary winding would on one limb while secondary
on the other but performance will be reduce.
To get high performance it is
necessary that other the two winding
should be very close to each other.
There are two type of core .
13. CORE COILASSEMBLY
In this Process the Winding Coil and Core is Assembled
Core Coil Assembly defines the insulation scheme, cooling,
dynamic withstand capability, handling.
Cooling is essential to prevent the thermal degradation of
insulation which enhances a transformer’s life.
The core assembly is vertically placed with the foot plate
touching the ground. The top yoke of the core is removed.
15. Tapping & Tap Changer
Generally Taps are provided on HV Windings for HV Variation
or LV Variation.
To achieve proper voltage regulation on load tap changer is used
instead of OCTC.
As it is mainly used for higher capacity transformers i.e. above
5000 KVA ratings, voltage can be supplied with On Load Tap
Changer along with necessary controls.
After this the CCA is placed in Vacuum Auto Enclave to remove
moisture content at 90°c.
16. TANK FABRICATION
Transformer tanks commonly used are of the following types;
1. Plain sheet steel tank.
2. Sheet steel tank with external cooling tubes.
3. Radiator tanks.
4. Tanks with corrugated wall panels.
The tank is manufactured by forming and welding steel plate
which is used as a container for holding the core and coil
assembly together with insulating oil.
18. TANK UP PROCESS
The core-coil assembly is taken out of the oven and the
"Muggers test" is carried out. If the merger value is as per the
specification then it is taken to Tank-up Dept.
After this test the Core-Coil Assembly is placed into the tank
and locked up, this process is known as “Tank-Up Process”.
Accessories are Fitted like drain valves, HV & LV Bushings,
conservator, oil level indicator and explosion vent are fitted in
Pure filtered transformer oil is filled in the tank to immerse the
20. After the Tank-up process the Transformer is Brought to the
In this process a zinc-32 rich primer is used to paint the
transformer tank for protection from corrosion.
21. TESTING OF TRANSFORMER
Following test used for the various purposes:-
1. Megger Insulation Test
2. Ratio And Polarity Test
3. High Voltage Test
4. Low Voltage Test
5. D.V.D.F Test
6. Open Circuit Test
7. Short Circuit Test
8. Winding Resistance Test
9. Oil Dielectric Strength Test
10. Vector Group Test
11. Magnetic Balance Test
23. APPLICATIONAND USES
The transformer used in television and photocopy Machines.
The transmission and distribution of alternating power is possible
Simple camera flash uses fly back transformer.
Signal and audio transformer are used couple in amplifier.
Less time require to assembling
Require less space
Deliver more power
Easier to install
Easy transportation and installation
Easy to repair
Greater cost of standby Units
Increased cost and inconvenience of repairs.
In Single Phase transformer (Three Single Phase
Transformer) failure of one transformer, the other two,
Single Phase Transformer still supply the power, while it is
not possible in case of failing a Transformer.