1. Sinhgad Institute Of Technology, Lonavala
Department of Electrical Engineering
A Presentation on
“ Failure and repair of transformer”
TE. Electrical, Roll No. TE16
Department of Electrical Engg.
Transformer is a static machine with very high efficiency and rugged construction.
Distribution Transformer plays a crucial role in the power distribution network. Failure of
distribution transformer results into interruption of power supply to consumers. This disruption
affects the economy of nation in the form of loss of revenue, materials, repairing charges etc
The rate of failure of distribution transformers in India is higher (12-17%) as compared to
developed countries (2-3%).
This high failure rate is cause of concern to all the Distribution Companies (Discoms) in the
Every year, nearly 200 Crore of Indian Rupees (INR) are spent by the Discoms for repair and
replacement of distribution transformers .
4. Literature Survey
1. Singh, R. and Singh, A, “Causes of failure of distribution transformers in India,” in Proc. 9th International
Conference on Environment and Electrical Engineering (EEEIC), Prague, Czech Republic ,2016.This paper
presents a detailed analysis of Transformer failure reasons and methods in conjunction with areal time data
of the electrical transmission and distribution system to find the reasons and its remedies for better
capacity utilization and reliability.
2. Mohsen Akbari, P. Khazaee, I. Sabetghadam and P. Karimifard "Failure Modes and Effects Analysis (FMEA)
for Power Transformers," in Proc. 28th International Conference on Power System, Tehran, Iran, 4-6,
3. S.S.Rajurkar and Amit R. Kulkarni, “Analysis of Power Transformer failure in Transmission utilities” in Proc.
16th National Power Systems Conference, 15th-17th December, 2010.
4. William H. Bartley, HSB, Transformers Failures, presented as Keynote Address at the annual ABB
Technical Conference, Alamo, TN, 2003.
5. 5 Working principle of Transformer
The transformer works on the principle of Faraday’s law of
electromagnetic induction and mutual induction. As per faraday’s
law of electromagnetic induction, this change in magnetic flux
induces an emf (electromotive force) in the secondary coil which
is linked to the core having a primary coil. This is mutual
Overall, a transformer carries the below operations:
1.Transfer of electrical energy from circuit to another
2.Transfer of electrical power through electromagnetic induction
3.Electric power transfer without any change in frequency
4.Two circuits are linked with mutual induction
6. 6 Causes of failure of transfomer
There are various electrical factors for transformer
failures which can be broadly classified in to following three
categories: Transient or overvoltage conditions; Lightening
and switching surges; Partial discharge.
Shipping of the transformer;
Transformer overloading for prolonged period;
Operation of transformer on nonlinear loads;
Failure of cooling system;
Blockage of oil ducts;
Operation of transformer in an overexcited condition;
Operation of transformer in high ambient temperature.
Repair Of Transformer
There are many factors to be considered when making the
decision on whether to have a failed transformer repaired
or to purchase a new replacement transformer.
The factors to be considered in making the decision will be
discussed in the folIow+g five sections of this paper:
1. Failure Statistics
2. Determination of Repair Cost
3. Repair Procedures
4. Loss Evaluation
5. Philosophy of Making The Decision
8. Advantages OF Transformer
• A transformer will increase or decrease basically AC voltage, current or
• It is efficient for high-frequency range
• The available power cannot change but will slightly too much decrease depending
on the efficiency of the transformer
• It has the advantage of preventing condensed flux leakage as well as iron loss
• It offers good mechanical strength
• The transformer is widely used in power transmission
9. 9 Disadvantages Of Transformer
•A transformer will not work with DC voltage under any condition
•The transformer size become un widely
•The physical size of the transformer is directly related to the amount
of power to be desired
•It is not good to use outdoors
•It can be noisy
• 1. Alternating Current Regulation
• 2. Charging Batteries
• 3. Steel Manufacturing
• 4. Controlling the flow of Electricity through a circuit
• 5. Audio Transformer
• 6. Air Conditioner
• 7. Stabilizers
• 9. Rectifier
• 10.For Step Up &Step Down Voltage
In India, failure rate of distribution transformers at an early age is very high. In practice, the life of a
distribution transformer can be as long as 30 years with appropriate maintenance but it lessens due to
lack of maintenance.
Two main reasons for low maintenance are –
(i) Most of them are located in remote areas and special attention cannot be given to the operating
conditions of the transformers.
(ii) A shortage of maintenance personnel working in State Electricity Boards (SEBs).