Insulators: Realities & Misconceptions

Editorial Columns, Insulators

The insulator industry ranks among the most intensely competitive within the entire electrical power business. As a result, commercial sources of information have not always painted a true picture of the state-of-the-art nor of actual service experience with the different technologies. It’s therefore understandable that some users have come to feel that they can’t separate fact from rumor. Therefore, based on 20 years spent covering the sector across more than 60 countries, I offer below some independent and objective observations:


1. Insulators are Critical to Power Network Performance

While generally regarded as a basic commodity with comparatively little technology content, the reality is that electrical insulators can prove the ‘Achilles Heel’ (i.e. fatal weakness) of every power system. Poorly performing insulators will doom even the best-built lines and substations to problems and invariably lead to frequent outages or high maintenance costs – or more likely both. This is an undeniable fact that elevates the strategic importance of the insulator to a level far in excess of its relatively minor cost.


2. Insulators Need to be Properly Specified in Order to Perform as Expected

While there are many reasons why insulators might fail in service, one of the most frequent is improper specification by the user. This is not to suggest that line and station design engineers do not know how to select insulators; rather the more correct explanation is that they too often do so with insufficient or inaccurate information on real site conditions. Without knowledge of the types of service stresses that will continuously be imposed on insulators, there is a risk they will be under-dimensioned, have less than ideal shed geometries, etc. etc.

3. Insulators Should Never be Purchased Based on Low Price Alone

There is no way to overstate the folly of buying insulators based solely on very low price. The life cycle cost of a high quality but expensive insulator is too cheap to worry about compared to all the other costs involved in building and operating power systems; the life cycle cost of low quality insulators can prove incalculably high.


4. Insulators Must Always be Handled Carefully

Since composite insulators are only growing in importance, special attention must be given to storing and handling them properly in order to avoid causing irreversible deterioration either before or during installation.


1. One Insulator Technology is Always the Best Choice

This is a completely wrong belief and deprives the user of benefitting from the comparative advantages offered by each alternative technology under different service conditions. One insulator technology is never universally the best choice; rather, users should always look at their specific application requirements and only then decide whether porcelain, glass or composite insulators will be preferred based on required service performance, local site conditions and total life cycle costs.

2. Insulators from Certain Countries are Inherently Low Quality

This widely circulated notion is at best misleading and more often than not totally false. It is usually intended to prejudice users against buying from certain overseas suppliers by suggesting that their products can never be trusted when it comes to quality. The simple truth is that one can find good and bad quality insulators coming from everywhere – at times even from the same supplier. Users must always exercise proper diligence and look carefully into manufacturing conditions, supplier qualifications and references whenever deciding to purchase something so critical to power system performance as electrical insulators.


3. Insulators Can be Installed & Forgotten

Most insulators offer service lives measured in decades, not years. However, this does not mean that they do not need to be inspected at regular intervals, the length of which will depend on the criticality of the line, severity of pollution stresses, past history, etc. The proper time to discover and correct an incipient problem is always before it leads to a costly failure.

4. Manufacturers are the Only Source Needed for Technical Input on Insulator Selection

Insulator manufacturers are typically, but not always, useful sources of information for users to turn to. However, just as the power sector has seen a loss of internal expertise over the years, so too some manufacturers have cut back technical departments in order to reduce costs. It is therefore probably unwise to make important decisions about insulator selection based solely on what one may hear from any one supplier.

One final truth: since the power delivery sector relies heavily on high-performing insulators, an appropriate level of attention must always be devoted to monitoring new developments in technologies and materials as well as the growing body of service experience worldwide.

Marvin L. Zimmerman

One thought on “Insulators: Realities & Misconceptions

  • February 23, 2016 at 11:47 am

    Good Article, gives good information about the realities and Misconceptions.

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