Transformer is a device on which cost effective supply of electricity mostly depends.so its maintanance is very important.

1. Transformer Diagnostics
Presented By:
Sanjeet Kumar
Registration No.-1308143
Branch:-Electrical & Electronics Engineering

2. Introduction
Transformer is a device on which cost effective
supply of electricity mostly depends.
The life measurement of the transformer is
made considering the following aspects:
a). Improvements over traditional time-based
maintenance, e. g. condition based or reliability
centered maintenance.
b). Maintaining a transformer in service.
c). Continuity of supply.
d). Priority of in-field repair and on line
processing.
e). Minimizing the remedy actions and making
the most effective remedial actions.
f). Comprehensive life assessment and/or
extension program.

3. Condition monitoring of power
transformer
Transformer health it is essential to employ
some form of monitoring to provide an idea
of when to initiate the above process. In case
of transformer monitoring, the following
questions are to be answered.
a) Is it normal?
b) Is there a fault?
c) Is the fault serious?
d) Is it fit for service?
e) What is its reliability?
The first two questions are answered
effectively by
i). Dissolved Gas Analyzer (DGA).
ii). Power factor/ Tan delta testing

4. Transformer maintenance process

5. Causes of Failure
Transformer is the heart of any power system.
Hence preventive maintenance is always cost
effective and time saving. Any failure to the
transformer can extremely affect the whole
functioning of the organization.
Many failures occur due to aging phenomenon:
•a). Shortened life due to accelerated deterioration of
components particularly bushing and OLTCS.
•b). Overheating of the HV winding coils due to poor
cooling excessive circulating current.
•c). Change in the condition due to ingress of water,
particle contamination, aging of oil, loosening of
contacts and clamping forces, vibration, unusual
stresses etc.

6. f). Three sources of excessive water may be developed in transformer
insulation
(i) Residual moisture in thick structural components not removed
during dry out.
(ii). Ingress from the atmosphere.
(iii). Aging decomposition of cellulose and oil.
g). Cellulose, fibers, iron, aluminum, copper and other particles
resulting from the manufacturing process are normally present in the
transformer oil. These form sludge particles slowly during normal and
overload operating temperature.
h). the present of bubbles may cause critical partial discharge (PD) to
occur even at rated voltage. Bubble evaluation is a problem of a “hot
transformer”

7. Dissolved Gas Analysis
Dissolved gas analysis is the most important test in determining the
condition of a transformer. Insulating oils under abnormal electrical or
thermal stresses break.
•The amount of gas detected in the sample is used to detect problems
with the insulation structure in the transformer. Data from DGA can
provide:
•Advanced warning of developing faults.
•Monitoring the rate of fault development.
•Confirm the presence of faults for scheduling Repairs.
•Monitoring of condition during overload

8. Resistivity or Specific resistance
Resistivity is the most sensitive property of oil, it varies greatly
with temperature. It is desirable to have resistivity of oil as high
as possible. Resistivity of oil reduces considerably due to
presence of moisture, acidity, solid contaminants etc.

9. Oil Analysis Techniques
The most common used insulating liquid is mineral oil. This is
due to low cost and its ready availability. Insulating oil used in
air breathing transformer has two important properties i.e. good
insulator and used as coolant.

10. Frequency Response Analysis (FRA)
• Frequency Response Analysis (FRA) testing by swept
frequency method makes a qualitative assessment of the
mechanical condition of the transformer core and winding.
The loss of mechanical integrity might occur due to:
• Large electromechanical forces due to fault Currents.
• Winding shrinkage causing release of clamping pressure.
• Transformer transportation and relocation.

11. Dielectric Dissipation Factor (DDF) or Tan
Delta
When an ac voltage is applied to insulation, the leakage current
flows, and this leakage current have two components, resistive
and capacitive.
A resistive component (IR) is in phase with voltage (V) and
capacitive component (IC) is 900 out of phase with the voltage.

13. Presented By:
Sanjeet Kumar
sanjeetkumar2101@gmail.co
+91-8968143473