Polymer Braced Post Insulators - NGK-Locke

1 CATALOG145 PolymerBraced PostInsulatorsNGK-Locke Polymer Insulators , Beach, Virginia, of CONTENTSB raced line post (BLP) Assemblies .. 2 Load Definitions .. 3 Types of BLP Assemblies .. 4 Braced line post (BLP) Assembly Swivel Horizontal V (SHV) Assembly Application Guideline for SHV Insulators .. 5 BLP Insulator Catalog .. 6 Braced line post using " LP .. 7 Braced line post using " LP .. 8 Swivel Horizontal Vee with " LP .. 9 Customer Design Form .. 10 Research & Development .. 11 Notes .. 12 NGK-Locke Polymer Insulators , Inc. management systems comply with the requirements of ISO 9001:2008 (Certificate#FM36580, since 1997) and ISO 14001:2004 (Certificate #EMS96014, since 2005); the registrar for both certificates isBSI Group America Inc.

2 , based in Reston, Polymer Insulators , line post (BLP) ASSEMBLIESA Braced line post assembly consists of a stay (sometimes called a brace or suspension)insulator, a strut (a post ) insulator and hardware that connects them to each other and to asupporting structure. The assembly forms a V shape away from the supporting structure,so it is often called a Horizontal Vee. More correctly, it should be called a Braced postassembly, because the strut ( post insulator) is not often horizontal. BLP assemblies simultaneously achieve dimensional compactness and the high strengthdesired for transmission lines.

3 Their compact form is derived from a standard line post (LP)which forms the strut component and allows for a narrow right-of-way. A high vertical loadcapacity is achieved with the addition of a stay. BLP construction is one solution to thegrowing demands of a modern society for transmission line designs that consider both theenvironment and the shows the relationship between the vertical loading capacities of LP ( ~ FRPcore) and BLP ( Braced line post with a FRP core) constructed of Polymer curves show the Maximum Design Load (MDL) level. As the chart indicates, the load-ing capacity of the BLP far exceeds that of the LP LengthVertical Loading " " " " " LPSmallShortLongFig.

4 1 Load comparison chartLarge2 NGK-Locke Polymer Insulators , DEFINITIONS The loads that can be applied to the BLP assembly at the conductor attachment point aredefined as follows:1) Vertical loadis the load perpendicular to the ground. The weight of a conductor andconnecting hardware, for example, create a vertical ) Longitudinal loadis a load along the conductor that the BLP supports. It is generatedby forces that are unbalanced from one side of the insulator to the other. Factors causingimbalance include: different conductor lengths (spans), changes in altitude, changes in con-ductor angle, wind and/or icing, and a broken conductor.

5 3) Transverse loadis a load along the post that is generated either toward or away fromthe supporting structure. Transverse loading toward the structure is Compression andloading away from the structure is Tension . Factors that can affect this type of loadinginclude post angle and wind 2 Load directionsNGK-Locke Polymer Insulators , OF BLP ASSEMBLIESThe two major types of assemblies are theBraced line post assembly, and the SwivelHorizontal Vee (SHV) assembly. Braced line post (BLP) Assembly:A BLP is a line post insulator that is bracedwith a suspension insulator (Fig.

6 3). BLPdesign takes into account the different typesof loading, but its greatest advantage is thatvertical load capacity is improved by thebrace. While longitudinal load capacity canbe improved, it generally depends on thestrength of the line post alone. Swivel Horizontal Vee (SHV) Assembly:A SHV is a Braced post insulator which has aswivel base connecting it to the supportingstructure (Fig. 4). The advantage of the SHVis that it resists longitudinal loads by swingingin the direction of the load. However, caremust be exercised in designing SHV.

7 Pleasesee application guideline for SHV insulatorson the next 4 Swive l Horizontal V ee (SHV)Fig. 3 Braced line post (BLP)4 NGK-Locke Polymer Insulators , GUIDELINE FOR SHV INSULATORSU nder extreme environmental conditionssuch as hurricanes or blizzards, SHVassemblies can experience unexpectedtransverse loads from high winds or loads are cumulative and are ampli-fied over the length of the system, whichcan lead to cascading collapse. But under normal service conditions, a well-designed system using SHV assemblies willsupport typical transverse guidelines or "rules of thumb" forsuccessful SHV application are shownbelow:A)The hinge angle should be greater than20 in order to increase longitudinal stability(refer to Fig.

8 4).B)The number of SHV assemblies insequence should be fewer than eight,depending upon span length and anticipat-ed wind loading, because insulator dis-placement (swing) is cumulative (see Fig. 5).C)Span lengths should be less than 700feet (213 m), depending upon hinge angleand number of consecutive )Compressive horizontal line (deflection)angles should be less than 2 .E)SHVs should not be used where theycan experience uplift, such as where thereare different elevations between the sup-porting structures, or where there is a pos-sibility of conductor s recommended that the user analyze allSHV applications.

9 This type of assemblyshould be used with caution where theguidelines must be exceeded. The analysiswill show whether the proposed installationis safe. Although unlikely, conditions may also arisethat cause the insulator to collapse ( ,excessive rotational deflection), even if theinstallation falls within the guidelines. Thepurchaser must carefully determine poten-tial excessive longitudinal behavior whendesigning this type of construction, the preferred methodof conductor stringing involves temporarilymounting the stringing sheave directly tothe supporting structure.

10 If the sheave ismounted directly to the SHV assembly, it isrecommended that the SHV be temporarilyanchored with ropes to keep the assemblyfrom longitudinal 5 Illustration of cumulative disp lacement of insulatorsNGK-Locke Polymer Insulators , INSULATOR CATALOGS tandard BLP assembly designs appear on the following pages. They may be ordered ascomplete sets, including all illustrated hardware, by referencing the catalog number. Uponrequest, combined load curves can be supplied for all BLP assemblies. All items carry theNGK-Locke standard addition to the items in this catalog, custom BLP assemblies can be designed to cus-tomer specifications.