Transformers

RLA Study

Condition Assessment Study

In this condition assessment package, we will assess the condition of the total insulation system of high voltage Transformers.

Condition Assessment Technique will be implemented as per following techniques listed below, which will assess the condition of Machine Insulation System in total. The various techniques are detailed as below.

1. DC Megger Tests
2. Capacitance & Tan Delta Analysis
3. Partial Discharge Analysis
4. DC Leakage Current Test
5. Winding Resistance Test
6. Sweep Frequency Response Test
7. Turns Ratio Test
8. Magnetic Balance & Vector Group Test
9. Voltage Balance Test
10. Magnetic Balance Test
11. Core Ground Test
12. Oil Tests
13. Online Partial Discharge
14. Thermography Inspection

The main objective of this life assessment will be to generate a report which gives the information to achieve following tasks 

  • To arrest the deterioration in performance
  • To improve the availability, reliability, efficiency and safety of equipment.
  • To regain lost capacity
  • To extend useful life beyond design life and save investment on new equipment.

Diagnostic Tests

Thermal, Electrical, Ambient (or environmental) and Mechanical (TEAM) stresses act on various components of Transformers, either singly or in combinations (thermo-mechanical, electro-thermal, electro-mechanical, etc), with varying intensities, depending on design, manufacturing, operating, maintenance and storage conditions, ultimately weakening (ageing, defect formation) the structure of the Transformer component (winding, insulation,frame,bushing etc) and ultimately resulting in failure. Based on various international surveys and studies it has been concluded that winding insulation is found to be the one of the maximum potential areas of failures in Transformers.
The main objective of this life assessment will be to generate a report which gives the information to achieve following tasks

  • To arrest the deterioration in performance
  • To improve the availability, reliability, efficiency and safety of equipment.
  • To regain lost capacity
  • To extend useful life beyond design life and save investment on new equipment.
PROGNOSYS provides Diagnostic Testing services for Transformers includes following techniques listed below, which will assess the condition of Machine Insulation System in total.

1. DC Megger Tests
2. Capacitance & Tan Delta Analysis
3. Partial Discharge Analysis
4. DC Leakage Current Test
5. Winding Resistance Test
6. Sweep Frequency Response Test
7. Turns Ratio Test

8. Magnetic Balance & Vector Group Test
9. Voltage Balance Test
10. Magnetic Balance Test
11. Core Ground Test
12. Oil Tests
13. Online Partial Discharge
14. Thermography Inspection

Online Partial Discharge Analysis

Partial discharges have been known to accelerate the aging process. They cause erosion of insulating material and propagate through treeing mechanism eventually bridging the electrodes and causing insulation breakdowns. While the Capacitance & Tan Delta tests gives us the indication of presence of these discharges, this test uses acoustic method to find partial discharges on the transformer.

Partial Discharge test will be done using Partial Discharge Analyser at normal running condition without disturbing the supply. PD Analyser system is used for partial discharge test that includes analysis software that gives discharge patterns for defect identification and also quantifies the partial discharge in the winding for trend analysis.

Thermographic Inspection

The principle of Infrared Thermography is based on the physical phenomenon that any body of a temperature above absolute zero (-273.15 °C) emits electromagnetic radiation. There is clear correlation between the surface of a body and the intensity and spectral composition of its emitted radiation.

By determining its radiation intensity the temperature of an object can thereby be determined in a non-contact way. Thermography has proven to be the best tool to find out the hotspots on transformer core,winding,bushings & other components in online condition using Thermographic cameras.

MILESTONES:

Prognosys will analyze the data and will submit a report that will include information relating to the following

  • Condition Assessment report for the Transformer frame,Bushing,winding……
  • Immediate recommendations to rectify any faults prevailing in the Transformer
  • Maintenance plan based on Condition of Transformer components obtained from the analysis report.
  • Recommends maintenance actions for life extension of Transformer based on the analysis report generated.
  • Report also includes recommendations on future testing schedules.