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Help - Q & A

  • General Quadri*Sil; and Hubbell Power Systems Questions
    • Why is Ohio Brass / Hubbell going with Silicone Rubber (SR)?
    • Hubbell Power Systems is expanding its product offering by introducing the new Quadri*Sil; – a Silicone Rubber Direct Bonded Transmission Insulator product line. This new product line is the result of several years of market research, materials research and a comprehensive new product development process undertaken to meet the requirements of a significant portion of the US and International market that prefers a Silicone Rubber Direct Bonded Transmission Insulator while continuing to innovate and manufacture tougher more durable insulators.

      • Are you making a change because of a problem?
      • No. Hubbell Power Systems and the Ohio Brass have always offered first class insulator products and we will continue to do so for the years to come. For a transmission insulator user's list please contact your HPS representative.

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    • What is Ohio Brass' / Hubbell's experience with SR?
    • In addition to our 40 years of experience with polymer materials for high voltage insulator applications, which include extensive practical experience with both EPM and SR based materials, Ohio Brass also has been manufacturing Silicone Rubber insulators for transmission and distribution voltages since 1996.

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    • What makes your Bonded SR insulator better?
    • Quadri*Sil; is the result of Ohio Brass' / Hubbell Power Systems' many years of research and development in combination with more than 30 years as a pioneer and key player in the High Voltage polymer insulator industry. The Quadri*Sil; stands to take the lead among all polymer transmission insulators due to our proprietary silicone rubber formulation for the insulator housing, its redundant-reliability four point sealing mechanism and its improved electrical performance under electrical gradients at the end fittings.

      • One piece shed design
      • Silicone rubber formulation
      • Redundant reliability four-point sealing system
      • Improved electric gradient at end fitting

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    • What does Quadri*Sil; stand for?
    • "Quadri" refers to the 4 different sealing mechanisms featured in our design and "Sil" refers to the Silicone Rubber housing material while also reminding us of the unique 4 point sealing mechanism that make the Quadri*Sil; the insulator with the best sealing mechanism in the market.

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  • Product Features and Design Questions
    • What's your manufacturing method?
    • Injection molded Silicone Rubber with Direct Bond between the sheath and the fiberglass core. The end fittings include an integral Corona Shielding Ring (CSR) and they are attached to the fiber glass using a radial high percentage circumferential crimp with 8 jaws.

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    • What is the SR content of your formulation?
    • Our proprietary-developed-in-house formulation is 100% Silicone Rubber before fillers and additives and 45% Silicone Rubber by weight. And the mixing and compounding are closely controlled and monitored by HPS to ensure consistency and quality in every batch of polymer material used for our polymer insulators.

      • Is 45% by weight enough?
      • Yes. Laboratory data shows that Silicone Rubber has excellent hydrophobicity and UV resistance but very low mechanical strength and resistance to tracking. Therefore, the reminder 55% with additives and fillers allows for an increased overall mechanical strength and tracking resistance in our formulation, while taking advantage of the hydrophobicity and UV resistance of the SR.

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    • How does Quadri*Sil; match up dimensionally and electrically against the Hi*Lite® XL or Porcelain?
    • The Quadri*Sil; insulators are very similar dimensionally and electrically to the Hi*Lite® XL and also to Porcelain Insulators. Finding a substitute or replacement for your Hi*Lite® insulators or Porcelain Strings should be very simple using our catalogs. You may also consult your HPS representative for application engineering assistance.

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    • What is that four point sealing mechanism?
      • Four Sealing surfaces
        • Surface 1 Counterbore Compression Seal
        • Surface 2 Radial Compression Seal
        • Surface 3 Polymer (RTV) Seal
        • Surface 4 Overlap Compression Seal
    • Integral CSR
      • Limits electric field gradients at the end fitting/polymer interface.
      Quadri*Sil Four Point Seal
    • Sealing surface 1
      • Compression seal at the blind end of the counter bore
      • 40 lb axial compression during crimp
      Sealing Surfaces
    • Sealing surface 2
      • Radial compression seal
      • Different angle on fitting and polymer
      • Radial compression
    • Insulator will pass moisture penetration test with these two seals alone.
    • Sealing surface 3
      • Polymer (RTV) seal
      • Channel between end fitting and polymer housing (outside of seals 1 and 2)
      • RTV fill cavity, Channel is 4x larger than fill hole
      • RTV bonds to metal and to silicone housing
      • RTV does not touch fiberglass rod
    • CSR shields RTV from electric field

    • cross section sealing surface
    • Sealing surface 4
      • Overlap compression seal
      • Contact between end fitting and raised notch in polymer
      • Creates the cavity for the RTV
      • Eliminates microsparking
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    • How do you crimp the end fittings?
    • We use a crimper to perform a uniform radial crimp with 8 die shoes which create a constant compression around the periphery of the end fitting until a statistically defined pressure is achieved.

      • How do you know you are not cracking the rod?
      • There are several steps to ensure a successful and reliable crimp.

        First, we perform thorough quality control checks for all our incoming component parts and materials; we check dimensions, galvanizing, material composition, etc.

        Second, we crimp to a pressure value and not to a given diameter. By setting the crimper to a statistically proven pressure, we avoid the possibility of over-crimping or under-crimping.

        And third, 100% of the units manufactured are tested to the RTL.

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    • What type of fiber glass rod are you using?
    • Since 2001 Ohio Brass has been using E-CR/Boron Free-E glass rod for its suspension and dead end insulators.

      • What's E-CR glass?
      • E stands for Electrical Grade Glass, CR stands for Corrosion Resistant. E-CR is a boron free special purpose glass fiber which offers enhanced long term acid resistance and short-term alkali resistance.

      • What does Boron Free mean?
      • It means that the Boron content of the fiber glass is negligible. The absence of boron in fiber glass is associated with several improvements on the performance of the fibers, some of those improvements are: improved corrosion resistance, higher density, higher dielectric constant. In particular, boron free fiber glass has been identified as a material capable of delaying a brittle fracture failure, because in the event of moisture ingress to the fiber glass rod, boric acid will not be able to form and therefore the fiberglass rod will not be subject to the damaging effect of this acid.

      • What is Brittle Fracture?
      • Brittle fracture can generally be defined as a series of cracks through a stressed material.

        In the case of brittle fracture on insulators, it is defined as a translaminar tensile failure which results after an electro-chemical attack to the resin matrix of the fiber glass rod.

        In the event that moisture becomes in contact with the fiberglass rod, the electrical activity breaks down the air, the water and the components of fiber glass into nitric acid, boric acid, ozone and other components. The nitric and boric acids attack the resin matrix and create a transverse (90deg) fracture to the plies (bundles) of fiberglass. The cracks run perpendicular to the applied stress creating a relatively flat surface at the break which typically covers between 40-80% of the cross sectional area of the fiberglass rod.

        The remainder portion of the cross sectional area typically has a series of stretched fiberglass fibers resembling a broken broom stick.

      • So Boron Free Fiber Glass means no Brittle Fracture?
      • No. Boron Free fiber glass will not eliminate the possibility of a Brittle Fracture. Boron Free fiber glass rod will only delay the brittle fracture by eliminating the possibility for Boric Acid to form, but since there will be other acids that will form, (such as Nitric Acid) brittle fracture will still take place but at a much slower pace.

        To completely avoid the possibility of a Brittle Fracture, insulator manufacturers need to avoid Moisture Penetration. That's why the new Quadri*Sil; with its innovative and reliable four point sealing system offers an insulator with redundant defense mechanisms against moisture ingress, and therefore a much more dependable insulator against brittle fracture.

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    • Why is your Corona Shielding Ring (CSR) larger in diameter?
    • Our integral Corona Shielding Rings and End Fittings have been designed using electric field analysis simulations in order to reduce electrical gradients which can create corona/RIV and damage the polymer material next to the end fittings. Our CSR has a larger diameter because we have optimized our integral design to provide you with the most reliable insulator in the market. With better gradient distribution in combination with our innovative sealing mechanism, Quadri*Sil; will push the reliability and durability industry levels to new heights.

      While our innovative design with larger geometry CSR provides superior e-field shielding, we recommend the use of external corona rings at voltages equal or grater than 220kV.

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    • What is a flash over?
    • When electrical activity achieves a magnitude capable of breaking the insulation level provided by the air around the insulator, electricity is then able to bridge/flash between two conductive materials, i.e the end fittings of the insulator. Other causes of a flash over or flash under may be: failure of the insulator sealing mechanism (water penetration to the fiber glass rod), an increase in the contamination level accompanied with moisture/humidity (bird streamer, salt used to melt ice, etc), and cases of misapplication, for example: selecting an insulator with not enough leakage distance, with not enough dry arc, etc.

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      • What is corona?
      • Corona can be simply defined as a discharge caused by electrical overstress. It can also be described in more detail as a luminous discharge due to ionization of the air surrounding a conductor around which exists a voltage gradient exceeding a certain critical value.

        There are three types of corona: plume, brush and glow.

        Plume Corona is most spectacular and it is so called because of its general resemblance to a plume. It also has audible manifestations which are rather intense snapping and hissing sound, these can be readily recognized by the experienced corona observer.

        Brush Corona is a streamer projecting radially from the conductor. These discharges generally occur all around the periphery of the conductor. The audible manifestation associated with brush corona is generally a continuous background type of hissing or frying sound.

        The glow corona is a very faint, weak light which appears to hug the conductor surface and there is generally no sound associated with it.

      • What is water droplet corona?
      • It is a type of corona that originates when water comes in contact with a Silicone Rubber (hydrophobic material) in the presence of an electric field.

        At the triple point junction between the droplet, the air and the insulating material (Silicone Rubber) the electric field is enhanced. This eventually leads to a local loss of hydrophobicity which can ultimately result in an increase on partial discharges and gradual degradation of the polymer material.

      • What are the implications of corona?
      • Heat, UV, Ozone, RIV: they all have negative effects on the performance of the insulator. That's why HPS has made special emphasis in the development of a Silicone Rubber formulation with superior corona performance. For a detailed look at our testing procedures, please refer to our white paper on Silicone Compounds for High-Voltage Insulators: HPS Testing of Silicone Compounds, available in the literature section of our website.

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    • What is dry band arcing?
    • Dry band arcing is known as electrical flashes that occur between wet and dry spots over the contaminated surface of an insulator.

      When the insulator is clean and dry the induced voltage has no significant effect. But, when it is polluted and wet, surface currents arise, which cause heat. The current density increases and tends to cause the greatest heat close to the fittings. As a consequence dry bands can develop when the supply of rainwater diminishes. These dry bands interrupt the conductive surface and this may cause arcing. Heating at the arc roots can cause tracking damage.

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    • What are scintillations?
    • A flash of light produced in a phosphor by absorption of an ionizing particle or photon. The process of scintillatio is one of luminescence whereby light of a characteristic spectrum is emitted following the absorption of radiation. This radiation is usually of a higher energy than the emission. Scintillation is an inherent molecular property in conjugated and aromatic organic molecules and arises from the electronic structure of said molecules. Scintillation also occurs in many inorganic materials, including salts, gases, and liquids.

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    • At what voltage do you need a corona ring?
    • Quadri*Sil; insulators require corona rings for applications at 230kV and above.

      • What sizes are your corona rings?
        • 8in ring for 230kV
        • 12in ring for 345kV
        • 8in ring and 12in ring for 400kV
        • 8in ring and 15in ring for 500kV
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    • How do you mark/label your insulators?
    • Quadri*Sil; Suspension insulators will be labeled with a UV resistant label that is placed on the ground end fitting. This label has been tested for outdoor and UV performance with successful results.

      Quadri*Sil; Line Post insulators will be labeled with a metal plate on the mounting base of the insulator.

      Both the label and the plate will contain manufacturers name, catalog number, mechanical rating, routine test/ proof test load and date of manufacture.

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    • Do you have CAD drawings available for these insulators?
    • Yes, drawings in CAD and PDF formats will be available for the Quadri*Sil; insulators.

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  • Testing, QA, Warranty, Packaging and Delivery Questions
    • What are your testing capabilities?

      Hubbell Power Systems has two fully equipped Laboratories and Research Centers capable of performing mechanical, thermo-mechanical, lightening impulse, flashover, and corona tests. Our research centers in Centralia, MO and Wadsworth, OH make Hubbell Power Systems one of the few insulator manufactures in the world to run its own research centers and laboratories. This is a clear demonstration of the level of commitment of our company to innovation and providing our customers with the best technical resources in the industry.

      • What testing do you do?
      • Our design engineers and our lab technicians perform mechanical, thermo-mechanical, lightening impulse, flashover, corona and all other tests required per ANSI, LWIWG and IEC standards

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    • Do you have third party IEC testing?
    • Yes, Quadri*Sil; are fully compliant with IEC and ANSI. For copies of our design test reports please visit the Documents section of our website.

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    • Are you ISO certified?
    • Yes, you can download a copy of our certificate from our website. For a copy of our certificate, please go to:
      ISO Certificate

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    • How do you package these insulators?
    • Wood crates
      Fork lift accessible from ends and sides
      Insulators supported at both ends and middle
      No weight on polymer weathersheds
      Weight distribution eliminates stress on core rod
      Rings packaged in crate with the insulators

      Samples of our packaging:

      Hubbell Power Systems sample packaging HPS Sample Packaging

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Hubbell Power Systems All contents Copyright© 2001 - Hubbell Incorporated. All rights reserved. Because Hubbell has a policy of continuous product improvement, we reserve the right to change design specifications without notice.
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