Our HDPE insulators exceed ANSI cantilever requirements of 3,000 lbs. Porcelain versions have not always met this criteria as confirmed by independent lab testing (NEETRAC).
Hendrix does not make formal suggestions for system protection design, it is always good to have sound grounding and lightning arrestor applications. Hendrix insulators exceed all ANSI specifications for electrical and mechanical performance.
In over 50 years of experience, there is no correlation to conductor size and failure rates. Most failures occur as a result of an over-voltage event, such as lightning, or a fault-current event, such as prolonged line-to-line or line-to-ground contact.
We use the NASA data, which identifies areas with historic frequency of lightning strikes.
Inherent in the design, the resultant performance of line post insulators provide greater flashover, impulse and puncture performance.
Hendrix polymer pin insulators are Guaranteed for Life.
While Hendrix does not stipulate maximum allowable angles, the tested cantilever ratings of all our insulators exceed the ratings of most mounting hardware (cross arm pins, ridge pins, etc).
95% of the material in a Hendrix insulator is 100% virgin high density polyethylene, with the balance a proprietary blend for UV resistance, track resistance, manufacturability, and color.
Radio Freed porcelain insulators have a semi-conductive coating on the top portion and pin hole threads to mitigate electrical discharge at air gaps which cause radio interference (RIV). HDPE insulators fill the thread well with non-conductive mastic to eliminate air gaps with the mounting pin thereby reducing the chance for electrical discharge and RIV noise.
With porcelain insulators it is common practice to use higher-class insulators than used inland for the same distribution system voltage levels. The porcelain surface is hydrophilic and small amounts of contamination, coupled with fog, mist or light rain can lead to frequent tracking, discharge and flashover at relatively low voltage levels. So application of porcelain insulators with higher leakage and flashover ratings made practical sense to reduce flashover incidence and related damage.
Polyethylene insulators are hydrophobic and non-polar, naturally repelling water and surface contaminants, making them less prone to flashover in coastal applications than their porcelain counterparts. Higher class HPI insulators may be used to further increase flashover withstand capability, but may lead to a higher rate of puncture in areas with high lightning densities.
There is a dielectric incompatibility between the materials which creates high electrical stress at the interface. Porcelain has a dielectric constant in the range of 6 to 8, while Polyethylene is 2.2 to 2.4. Over time, the electrical stress at the interface can lead to destructive discharge and tracking, causing conductor covering erosion and puncture.
Porcelain insulators with a Radio-Free semi-conducting coating create even higher electrical stress at the covered conductor interface and should be avoided.
No. In actuality, the conductor and tie (or Vise jaw) will hold the insulator in place to prevent any rotation. Hendrix polymer pin insulators are installed in all 7 continents and all 50 states in the U.S.
The failure rate of polyethylene insulators is less than one-tenth of one percent (0.1%). We do not have data on porcelain.
HDPE is 100% recyclable. It is the same as a #2 rated plastic (i.e. milk cartons, water bottles). Porcelain has no redeemable after life except as landfill. When broken, it is a sharp and dangerous by-product.
Reference NEETRAC Distribution Insulator Performance Evaluation, baseline project no. 07-146, dated March 2010. NEETRAC compared 8 porcelain pins with Hendrix, and the results are clear.Hendrix out-performed all the porcelain by a wide margin.
Polyethylene is a naturally hydrophobic, non-porous material lending to easy natural cleaning via normal rainfall. Porcelain relies on the glazing to seal and protect from the elements. Any breakdown in this protection can lead to contamination buildup and ultimate failure.The hydrophobicity of polyethylene is much greater than that of porcelain.
Vise Tops will provide adequate grip the on conductor to varying degrees depending on wire size and type. Many users prefer the Vise Top for the benefit of being able to easily re-sag the line in the event of unintended loading rather than complete damage to the cross arm and pole. We can supply grip strength information on the Vise Tops.
No.The first generation Vise Top and new Universal Vise Top insulators with plastic and composite inserts, respectively are specifically designed to maximize performance without damage to covered conductors.
Yes. NEETRAC performed a comprehensive test comparing porcelain pin insulators to polymer pin insulators in 2010. The polymer pin insulators outperformed the porcelain by far.
Yes, we offer line post insulators for a range of distribution systems. You can find them in our catalog and website, www.HendrixHPI.com.
After a Vise Top insulator is installed, there remains a hex bolt head that allows bolt removal/replacement with a standard socket or wrench. The shear bolts allows for the proper and consistent amount of tightening while allowing indication of completed installation.