MPS Polymer Cutout Advantages

1 MacLean Power Systems


I. Cutout Design & Function1. Function

a. Purposeb. System construction

2. Terminologya. Common termsb. Cutout components

3. History

II. Cutout Standards1. Current standards

a. IEEE / ANSI b. CSAc. IEC

2. Evolution of standardsa. NEETRAC b. IEEE / ANSIc. Considerations

3. Design testsa. Standard testsb. MPS testsc. NEETRAC proposed


III. Advantages of Polymer1. Design

a. Material b. Insulationc. Thermal cycling

2. Installationa. Durabilityb. Weightc. Handling

3. Maintenance & operationa. Core strengthb. Safetyc. Lifecycle & replacement

IV. MPS Cutouts1. Design advantages

a. Transmission experienceb. Silicone vs. EPDMc. Cored. Shed patterne. Fittingsf. Hardware

2. Service advantagesa. Domestic factoryb. Storm capabilities


I. Cutout Design &

Function


a. Purpose• Over-current protection

- System demand- Short circuits- Various fault types

b. System construction• Overhead distribution • All distribution kV classes• Commonly applied in front of transformers• Applied prior to beginning underground line

http://www.youtube.com/watch?v=zAxGBHZtUM0&feature=youtu.be

http://www.youtube.com/watch?v=zAxGBHZtUM0&feature=youtu.be


a. Common terms

• Interrupt Rating- Maximum short-circuit current the cutout device can interrupt, extinguish, and clear under standard test conditions

• Basic Insulation Level (BIL)- Measure of withstand for surge voltages such as lightning or system switching

• Dry Arc - Distance of the shortest path from line voltage to ground

• Leakage- Distance from line voltage to ground when the current path is along the insulation surface


b. Components

Fuse support / body

Arcing horns / guide

hooksLower contacts

Parallel-groove clamp

Trunnion

Flipper

(under trunnion)

Fuse tube ferrules

Fuse holder / tube /

door

Lower hinge

Upper contact spring

Sleet shield

Upper contactCenter bracket

Hook stick ring / eye


Arc-extinguishing

linerArc-shortening rod

Cap Fuse link

Flipper

spring

• Fuse holder- Current interrupt rating specific- Filament wound tube to support fuse link- Reusable, but liner must be inspected after interruption- Arc energy used to convert synthetic liner to di-electric gas

• Fuse link- Selected by current rating and system coordination- Replaced after every over-current incident- Time / Current characteristics control melt speed


• General- Cutout patents date back to 1930- Up to mid 1990’s each manufacture had unique fuse holder dimensions

• Fuse tube- Bone fiber or fish paper

- Problems with moisture absorption and swelling- Durability

- S&C fuse tube design patented 1980 with synthetic lining- Current tubes are constructed from fiberglass

• Insulator- Porcelain devices- S&C silicone insulator patent filed 2002- MPS silicone cutouts 2010


II. Cutout Standards


a. IEEE / ANSI• Institute of Electrical and Electronics Engineers Power & Energy Society

-Shares developments in the electric power industry, creates standards for the development and construction of equipment and systems, and educates industry and the general public-Switchgear subcommittee is the controlling body for cutouts standards

• ANSI / IEEE C37.41-2008 Standard Design Tests -Power Frequency Dry Withstand-Power Frequency Wet Withstand-Impulse-Interrupting Test Series 1 – 5-Radio Influence -Temperature Rise-Manual Operation-Thermal Cycle-Bolt Torque

• ANSI / IEEE C37.42-2009 Standard Specifications -Tables specify test values for design tests listed above-Currently under revision with long term goal to roll C37.42 into C37.41


b. CSA – Canadian Standards Association

• C310-09 Distribution Class Polymeric Cutouts - References C37.41 & C37.42- Additional tests for polymer fuse supports, based on distribution insulators- Additional mechanical tests- Interchangeability clause- Bolt torque

• Concerns with C310-09 Specifications - Tracking & erosion test is at fixed 35V/mm leakage, not system voltage, penalizing high-leakage designs- Interrupt interchangeability of fuse tubes has no standard - annex A.5.4 suggests customers to inquire with manufactures

c. IEC• Used internationally in European, African, and many Latin American and Asian countries


a. NEETRAC• School of Electrical and Computer Engineering at Georgia Tech• Self-supporting, membership based testing & research center

b. ANSI / IEEE• C37.41 – porcelain cutout standard evolving to cover polymer cutouts

- Currently under revision- Incorporating sections of C37.42- NEETRAC polymer working group has proposed recommendations to IEEE committee to include tracking & erosion, mechanical tests on fuse support and interruption at temperature extremes

• C37.42 – phasing `out-Currently under revision-Many sections being moved to C37.41-Next revision most likely to be the last change

c. CSA• CSA 310-09

-Test parameters should be reconsidered-MPS has not participated in this committee


a. Standards Tests•ANSI / IEEE C37.41-2008 Standard Design Tests

- Power Frequency Dry Withstand Tests insulator design and construction by holding a specified voltage for a period of time

-Power Frequency Wet WithstandSame as above but in a simulated high humidity or rainfall environment

- Impulse (BIL): Tests insulation level to protect against surge voltages such as lightning or system switching

-Radio Influence Voltage (RIV)Tests to ensure the design does not create electrical noise

- Interrupting Test Series 1 – 5Tests the entire cutout system to interrupt different over-current conditions


a. Standards Tests cont.•ANSI / IEEE C37.41-2008 Standard Design Tests cont.

- Temperature RiseTests resistance factors (i.e. contact pressures, material selection and design)

- Manual OperationTests ability to function properly after 200 open and close operations

- Thermal CycleTests design integrity during thermal expansion/contraction

- Bolt Torque Tests hardware up to at 125% of nominal manufacturer-specified torque values


b. MPS Tests• 3 point bend – Test glass core rigidity• Water Diffusion

–Tests fiberglass core integrity and silicone bond to core• Dye penetration

– Tests fiberglass core integrity & end fitting seal• Torque

– Tests crimp joint integrity and fiberglass core strength• Tensile test – Tests fiberglass core and end-fitting strength• Loadbuster – Tests mechanical operation using S&C Loadbuster device

c. NEETRAC proposed testing• Insulation Test (42 hr boiling water / steep front impulse / withstand)• Water Diffusion Tests (CSA 7.4) • Interruption Test Series 1 at +50 °C and -50 °C • Tracking & Erosion • Weathering - UV Aging • Long Term Deformation


III. Advantages of

Polymer


a. Material• Polymer types

- PTFE – Polytetrofluoro ethylene- EPR – Ethylene propylene rubber- EPDM – Ethylene propylene diene methylene- SIR – Silicone rubber

• Inherent resistance to pollution & are hydrophobic• Pliable material vs. brittle porcelain material• Weight differential (1:10)• Engineered material – easy to mfg.

b. Insulation1

• Increased leakage• Greater dry-arc distances lead to higher kV flashover levels• Better performance in polluted environments 2-4


c. Installation• Durability & Handling

- No possibility of chipping- Higher impact resistance- Cutout/arrester combo units save new install time

• Weight- Freight savings- Easier warehouse handling

• Safety- Ergonomics – low extended weight when installing- No potential sharp edges

Chipped Porcelain


a. Strength of fiberglass core over repeated interruptions and closures

b. Safety• No sharp edges due to damage (hail/ice)• No possibility of cracking or shrapnel dispersion under

catastrophic events

c. Lifecycle & replacement• Longer lifecycles in polluted environments• No possibility of cracking due to thermal cycling • Reduced vandalism threat• Easier & cheaper disposal due to lighter weight

Cracked Porcelain

Fractured Porcelain


IV. MPS Polymer

Cutouts


a. MPS is an experienced leader in insulator design• 25+ Years and 29 million years of installed service life • Designs up to 500kV• All environments • This experience is designed into our cutouts

eJournal of New World Sciences Academy, 2007 V2, N4, A0038

b. Advantages of Silicone vs. EPDM 5-10

• Superior flashover performance• “Recovery” of hydrophobic properties 11-13

• Superior UV & aging performance 14

• Chemically inert – unaffected by pollutants


c. Core• Boron-free/corrosion resistant E-glass core15

• High-strength to withstand dynamic loads during interruption & fuse replacement• 3-point bend sampling tests

d. Alternating Shed Pattern• Meets IEC 60815-1, 3 for polymer selection & dimensioning in polluted conditions

- s/p well above major competitors- Sufficient C (distance between sheds)- Lower l/d (leakage distance vs. clearance) than major competitors- Lower l/A (leakage over arching distance) value

• Superior pollution performance (including ice)16

s/p

l/d


e. Fittings• Crimped on fittings

- Prevents rotation and alignment issues- Provides mechanical barrier against moisture ingress

• Over-molded rubber design provides additional barrier against moisture ingress

f. Hardware• Thicker sleet-shield prevents deformation and upper contact

pressure issues• Thicker top contacts prevent deformation after interruption or

mishandling• “Floating” top contact design provides sufficient pressure should a

non-MPS fuse holder be installed• Dimpled top contact prevents over-closures• Gentle top contact angle allows for easier closing• Eyebolts & parallel groove clamp connector options


a. Domestic Factory• Polymer cutout assembly in York SC• Domestic stocking of components• Short lead times & disaster recovery

b. Storm Capabilities• Cross-trained operators allow capacity-flexing in emergencies• Capabilities for 3 shifts 7 days a week• York location is out of typical disaster areas, yet in 1-2 days proximity to

major shipping lanes & destinations


1. James, F.H., (1993). History and Bibliography of PolymericInsulators for Outdoor Applications. IEEE Transactions on PowerDelivery, Volume:8, No:1, pp:376-385.2. Jahromi, A.N., El-Hag, A.H., Jayaram, S.H., Cherney, E.A., Sanaye-Pasand, M., and Mohseni, H., (2006). A Neural Network Based Methodfor Leakage Current Prediction of Polymeric Insulators. IEEETrans. on Power Delivery, Volume:21, No:1, ppApplication guide for Composite Suspension Insulators, SEDIVER,Paris, 1993.3. Houlgate, R.G., and Swift, D.A., (1990). Composite Rod Insulatorsfor AC Power Lines: Electrical Performance of Various Designs at aCoastal Testing Station", IEEE Transaction on Power Delivery,Volume:5, No:4, pp:1944-1955.4. Houlgate, R.G., Swift, D.A., Cimador, A., Poubaix, F., Marront,G., and Nicolini, P., (1986). Field Experience and LaboratoryResearch in Composite Insulators for Overhead lines. InternationalConference on Large Electric High Tension Systems (CIGRE),Paper:15-12.:506–507.5. Van Der Huir, R., and Karner, H.C., (1989). Evaluation ofPolymeric Insulating Materials for HV Outdoor Applications.Proceedings of 6th ISH, 30.02.6. Pilling, J., Chrzan, K., Hofmann, J., and Baersch, R., (1993).Artificial Aging of Polymer Insulation Surface in a Clean FogChamber and its Evaluation. Proceedings of 6th ISH, Volume:2,pp:165-188.7. Fourmigue, J., Noel, M., and Riguel, G., (1995). Aging ofPolymeric Housings for HV Insulators- Comparison Between Naturaland Artificial Testing. Annual Report of CEIDP, pp:404-407.8. Otsubo, M., Shimono, Y., Hikami, T., and Honda, C., (1996).lnfluence of the Humidity on Leakage Current under AcceleratedAging of Polymer Insulating Materials. Conference Record of ISEI,pp:267-270.

9. Zhao, T. and Sakich, J., (1996). Salt Fog Aging on Non-CeramicInsulators and Fog Chamber Data Acquisition System. Annual Reportof CEIDP, pp:377-380.10. Gorur, R.S., De la, O.A., El-Kishky, H., Chowdhary, M., Mukherjee,H., Sundaram, R., and Burnham, J.T., (1997). Sudden Flashover ofNonceramic Insulators in Artificial Contamination Tests. IEEE Transaction on Dielectrics and Electrical Insulation, Volume:4,No:1, pp:79-87.11. Kim, S.H., Cherney, E.A., and Hackam, R., (1990). The Loss andRecovery of Hydrophobicity of RTV Silicone Rubber InsulatorCoatings, IEEE Transactions on Power Delivery, Volume:5, No:3,pp:1491-1499.12. De Decker, D. and Wright, S., (1993). Recovery and HydrophobicityTransfer in Silicone, SEE Symposium on Composite PolymerInsulators.13. Chang, J.W. and Gorur, R.S., (1994). Surface Recovery of SiliconeRubber Used for HV Outdoor Insulation. IEEE Transactions onDielectrics and Electrical Insulation, Volume:1, No:6, pp:1039-1046.14. Sherif, E.M., (1987). Performance and Aging of HVAC and HVDCOverhead Line Insulators, Ph. D Thesis, Chalmers Institute ofTechnology, Sweden.15. Kumosa, M., Kumosa, L., and Armentrout, D., (2001). FailureAnalyses of Nonceramic Insulators Part 1: Brittle FractureCharacteristics. IEEE Electrical Insulation Magazine, Volume:21,No:3, pp:14-27.16. Matsuoka, R., Ito, S., Tanaka, K., and Kondo, K., (1997). Contamination Withstand Voltage Characteristics of Polymer Insulators. ISH97 Montreal, pp:81-84.

MPS Polymer Cutout Advantages

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