Insulators and traverses: what do they have in common and why is it important? 

When they talk abouttraverse insulator, many, especially those new to the network business, immediately think about the traverse itself. But no. The attachment point of the insulator to the cross-beam is often confused with the cross-beam itself. A traverse is a supporting structure, a beam. But how the insulator is screwed to it, what kind of fasteners are used, a bushing or a suspended insulator - this is a separate story, on which the reliability of the entire guy wire or support depends. Actually, the “insulator-traverse” connection? - this is one of the most vulnerable places if you approach the matter carelessly.

Design nuances that you won’t see in the catalog

Let's take, for example, a standard traverse for an intermediate support of a 10 kV overhead line. It would seem that everything is simple: a steel corner, holes, studs. But here is the first nuance: the hole for the insulator fastening pin. If it is made without a chamfer or with burrs, when the nut is tightened under load (wind, ice), stress is concentrated in this place. A microcrack in the paintwork, and after a couple of seasons - a source of corrosion. I saw this on old domestic traverses. It might seem like a small thing, but it reduces the service life of the unit by years.

The second point is the material of the traverse itself. Galvanized steel is standard. But the quality of galvanization varies. I remember a case when, during installation in a coastal area with an aggressive environment, traverses with a thin layer of zinc began to “bloom”. red spots after the first winter. We had to urgently organize touch-up painting, which on a site-wide basis would require additional labor. Therefore, now I always look not only at the passport data, but also at the actual thickness of the coating, sometimes I even ask to provide a sample for verification.

And the third, most important nuance is the compatibility of the traverse seats with a specific insulator model. Manufacturers of insulators often change the dimensions of the flanges and the diameters of the mounting holes. And the designer sometimes takes data from an old album of standard solutions. As a result, there is an inconsistency at the facility: the studs do not fit, or the insulator “hangs loose?” You have to either drill holes (which weakens the structure) or look for transition elements. The ideal situation is when the supplier, such asShijiazhuang Hist Electric Co.,Ltd, offers a comprehensive solution: traverses already adapted for fastening specific lines of insulators, which they also produce. This eliminates a lot of headaches during installation. On their websitehiste-ru.comIn the cable fittings section you can clearly see that the approach is systematic - from the insulator to the fastening unit.

Field experience: installation and typical mistakes

In theory, installing an insulator on a traverse is a five-minute operation. In practice, it is a source of constant risk. The most common mistake installers make is overtightening the nuts. It seems that the tighter you tighten it, the more reliable it is. But for porcelain or polymer insulators this is fatal. A pinched flange causes microcracks in the insulator material. In porcelain they are invisible to the eye, but at the first serious mechanical impact (for example, the release of an ice load), the insulator can simply crack. With polymer ones it’s a little better, but even there the deformation of the UV-stabilized polymer leads to accelerated aging.

Another point is the use of the wrong thing or “everything in a row?” fasteners The stud should be hot galvanized, not just painted. Nut - preferably with a nylon retaining ring or flange so that it does not unscrew due to vibration. I saw how on a temporary overhead line they used ordinary “black” ones for a construction site. bolts with lock washers. After six months of use in the autumn dampness, they became tightly stuck, and active corrosion began under the bolt heads. During dismantling, I had to cut it with a gas cutter.

And, of course, alignment. The traverse must be installed strictly in level, otherwise the insulator works with eccentricity and the load is distributed unevenly. This is especially critical for hanging garlands. One day we were adjusting the guy wire for the antenna mast. The installers slightly skewed the traverse and decided that “it will do just fine.” After a year of constant wind load, one of the insulator plates in the garland was literally torn apart - a crack started from the point of contact with the incorrectly oriented eye of the traverse. Knottraverse insulatorfailed not because the materials were bad, but because of an error during the installation stage.

Questions of choice: what the market offers and what to look for

Now on the market, if we talk about components, we can roughly divide the offers into three categories. The first is standard traverses and standard insulators from large electromechanical plants. Reliable, but often ?hard? according to standard sizes, without flexibility for a non-standard project. The second is handicraft production, where they can make it “as in the drawing?”, but the quality of the metal and coating is always a lottery. And the third is specialized manufacturers of cable fittings, which precisely fill the niche of competent pairing of elements. The latter includes the companyShijiazhuang Hist Electric Co.,Ltd. Judging by the description on their website, since 2004 they have been dealing specifically with accessories for cable networks, and this implies an understanding that the insulator and its attachment point are a single system.

When choosing, I always first look at the fastening unit in the catalog or, better yet, at a real sample. It is important that space is provided for installing a spacer washer or gasket between the crossmember steel and the insulator flange. This prevents electrochemical corrosion from contact of dissimilar materials. It is also good if the design of the traverse includes the possibility of installing an additional grounding clamp directly on it, and not on the wire.

Another practical tip is to pay attention to weight and ergonomics. The traverse with already installed mounting pins for insulators must be such that the installer can lift and install it on the support manually, without a crane, if we are talking about overhead lines up to 35 kV. There are designs where the pins stick out in all directions - they cling to everything when lifting, and are easy to bend. Ease of installation is also part of reliability, because the more difficult and inconvenient it is to assemble, the higher the chance that it will be done somehow.

Case study: repair instead of replacement

I would like to give an example of where attention is paid to the insulator-traverse unit. saved time and money. At one of the 6 kV substations the walk-through was out of ordertraverse insulatoron input. More precisely, the porcelain insulator cracked. The standard solution is to disconnect, dismantle the entire traverse with inputs, and replace the insulator assembly. But upon inspection, it turned out that the traverse itself and its fastening elements were in perfect condition, there was no corrosion. The problem was only in one specific isolator. After studying the catalogs, we found a modern polymer insulator with exactly the same mounting flange from the same valve manufacturer. There was no need to change the entire structure or rework the fasteners. We replaced only the damaged element, selecting it according to the geometry of its attachment to the existing traverse. The key role was played by the unification of landing dimensions, which is offered by serious manufacturers. This is about the importance of standardization even in such seemingly small things.

This case also showed that the condition of a node cannot be assessed only visually. After dismantling the cracked insulator, we checked the tightening torque of the nuts on the neighboring ones, which seemed to be in good working order. On two of them, the torque was significantly lower than normal - the nuts had weakened due to vibration over the years of operation. So now, for any repairs related to this unit, the list of mandatory work includes preventive broaching of all fasteners with a calibrated torque wrench. A small operation that prevents a major accident.

Instead of a conclusion: what is always worth remembering

So, if we summarize the accumulated experience, then the combination of an insulator and a traverse is not just “screwed and forgotten”. This is a dynamic unit that is constantly experiencing mechanical and climatic loads. Its reliability is determined by three factors: the quality of the components themselves (both the steel of the traverse and the insulator), the correctness of their pairing at the design stage and, most importantly, the culture of installation and maintenance.

When dealing with such elements, it is always useful to deal with suppliers who think systems. When the manufacturer, howShijiazhuang Hist Electric Co.,Ltd, offers not just insulators or not just traverses, but comprehensive solutions for cable lines, this reduces the risks of incompatibility. Their experience, listed in the company description since 2004, as a manufacturer of cable accessories, usually means that they have encountered these field problems and built the solution into their products. It’s easy to check: you need to request not only certificates, but also installation recommendations, or better yet, talk to a technical specialist. His answers to questions about vibration, corrosion and installation tolerances will tell you more about the product than any fancy catalogue.

Ultimately, every little thing matters in our business. And the attachment point for the insulator to the traverse is exactly that “trifle” that determines whether the line will last the guaranteed 25 years or will begin to crumble in ten. It's worth giving it the attention it deserves.