The document reviews various bushing technologies for transformers, focusing on improving reliability and safety through risk assessment and innovative materials. It discusses the advantages of resin impregnated paper (RIP) and highlights alternatives like fiberglass impregnated glass, offering greater resistance to mechanical and thermal stresses. The document outlines a step-by-step smart plan for replacing aging bushing fleets based on risk factors and technology types.

1. Increasing Transformer
Reliability by SMART Bushing

2. OVERVIEW TECHNOLOGIES
Types RBP OIP RIP RIS RIF
Insulation Srbp Paper+Oil Paper+Epoxy Synth+Epoxy Glass+Epoxy
Tan δ 0.7 0.4 0.4 0.35 0.3
Pressure Nil Yes Nil Nil Nil
Life 25 40 40 50 50
Population 8 % 80 % 10 % 1 1
PD high <10pC <10pC <10pC <10pC
50 % of
failure-
>fire

3. FAILURE ANALYSIS…EUROPE
45%
7%
1%
17%
3%
26%
1%
Windings
Lead exit
Insulation
Bushing
Core
Tapchanger
Others
50%
>400kV
RD2

4. Slide 3
RD2 Ramachandran Damodaran, 05-08-2016

5. ROOT CAUSE ANALYSIS
80% leakage (OIP Bushings )
13% deterioration of insulation
7% mechanical damage (mainly
porcelain insulators)

6. WEAK LINKS
Water
accumu
late
High
RPN

7. Summary of IMPROVEMENTS
BY PROBLEM SOLVING + FMEA
LOWEST RPN ON SEALING
- ALL JOINTS – UNDEROIL
LOWEST RPN ON CONDUCTOR
- CASTINGS – WELDING
RISK REDUCED AT TOP CONNECTION
- 3 NOS TAPPED HOLES
HEAT SINK FOR HOTSPOT
- SOILD TOP TERMINAL
CURRENT SHARE EQUALLY
- PLANETARY + SINGLE PIECE
ELCTROPLATING DEFECTS
- ELECTROLESS
We understand and We care

8. SOME CASE STUDIES
NO WELDING –better
conductance
INTEGRAL terminal –
thermal performance
Electroless
Nickel

9. SOME CASE STUDIES
JOINTS ABV
OIL LVL

10. SOME CASE STUDIES
JOINTS ABV
OIL LVL

11. AGEING of BUSHING
High ambient temperatures & temperature changes
High & frequent load cycles (e.g. pump storage power plants)
Overvoltage/transients (switching, lightning, harmonics)
Leakage à moisture ingress
Oil leakage (OIP only) à loss of insulation/dielectric properties
Corrosive contaminants in oil (for OIP only)
Capillary cracks (RBP types)
Partial discharges

12. SMART PLANS
Step 1: Identify & Clustering Bushing Fleet
• Voltage level
• Current level
• Technology
• Age
• Type of transformer
• Importance of substation

13. SMART PLANS
Step 2: Risk Assessment of Installed Bushing Fleet
• Based on Age
• Site Measurements
- Tandelta + Capacitance
- thermography
- Dissolved Gas Analysis-oil sampling
- Partial Discharge limited by background noice
< 1% OK
1`2%..??
>2%..ICU

14. Step 3: Definition of Bushing Style to Replace
Installed Fleet
Step 4: Set Up Risk-Based Replacement Schedule
Step 5: Execution of Bushing Fleet Replacement
Strategy

15. THANK YOU

16. OIL + PAPER INSULATION
Oil Impregnated Paper (OIP)
Century Old Proven need Long Process time
Need Monitoring of oil level + Quality
Moisture settles down at most stressed part
Failure may lead to a devastating fire

17. RIP IS POPULAR
MANY
APPLICATIONS

18. RESIN + PAPERRESIN + PAPERRESIN + PAPERRESIN + PAPER
Dry type Resin Impregnated Paper (RIP)
A big relief against the nuance of oil
But RESIN do not marry PAPER well
Long Process time to remove water from paper
SLOW Impregnation of RESIN to Paper
PAPER absorb moisture STORAGE in store
RIP is BETTER than OIP but not the BEST
being fully dry and pressure-free;
• featuring a higher temperature class;
• being partial-discharge free;
• having low dielectric losses;
• being fire resistant, and;
• having outstanding mechanical properties

19. SEARCH FOR Alternative to RIP…..
ABB
MICAFIL

20. RESIN INFUSED GLASS
Most proven FRP system Resin Infused Glass widely
accepted from Boat to Aircraft
Superb Electrical and Mechanical properties
Popular for Polymer INSULATORS, Wind Mill etc..
Factory tested values retain life Long
P.Keith Ellis ..IEEE ex.chairman…
“….seen many failures of RIP leading fire…if you need a
safer bushing for transformer…look in to fiberglass
impregnated Glass.

21. RESIN +GLASS
Safer, no risk of fire and explosion.
Totally maintenance-free, low cost of ownership.
Superior resistance to mechanical and thermal stresses.
Environmentally friendly – no risk of toxic leakage.
Sealed and impervious to water and pollution.
Real time tracking for unmatched peace of mind.

22. MGC
PCORE
TRENCH

23. BETTER with POLYMER HOUSING

25. TRANSFORMER BUSHINGSTRANSFORMER BUSHINGSTRANSFORMER BUSHINGSTRANSFORMER BUSHINGS
No
Grading
with
Grading