In general, arresters for HV applications (typically
52 kV and higher) have experienced the same fundamental shifts in technologies
as have been seen in the area of distribution arresters (see Part 1 of this
article in the Nov-Dec 2002 issue). However, the pace of acceptance of these
developments by utilities has in general been much slower.
In the 10 year period between 1986 (when the new MV
polymeric designs first became readily available in the marketplace) and 1996,
the distribution arrester market converted almost entirely away from porcelain.
However, in the 10 years since their appearance on the market in the early
1990s, polymeric-housed HV arresters have so far succeeded in capturing only
about one-third of the total HV arrester business.
This different rate of market acceptance has been due
to several factors. For example, unlike the case for porcelain-housed arresters
used on distribution lines, porcelain arrester designs for station applications
have had a generally good service record. At the same time, many users perceive
greater risks in adopting new designs and materials in applications such as
station arresters where failure can much more severely affect a network. As one
industry executive puts it, “these arresters are protecting the major
assets of the utility. Therefore, it is critical that they work properly for
periods of up to 25 or 30 years, depending on service conditions.”
Nevertheless, in spite of the cautious reception of
this technology among users up to now, the major suppliers in the arrester
industry have continued to further develop new polymeric design alternatives.
Indeed, it appears that most HV arrester suppliers are themselves convinced
that these designs will eventually represent the future for the category, much
as polymeric MOV arresters have become the standard for distribution
applications.
The latest arrester designs and housing materials
have also opened up an interesting new area of application, namely on overhead
transmission lines. To date, the overwhelming proportion of HV arresters have
been installed at stations. However, there is a general belief in the industry
that the growing emphasis on reliability will now support more and more
installations of such arresters on overhead networks.
The following article examines these basic issues and
provides readers with an overview of the HV arrester field - from market
characteristics to the alternative new technologies, materials and designs
which have recently become available.
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Market Factors &
Structure |
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There seems to be quite a large variation in industry
estimates of the size of the world market for HV arresters – anywhere from
as little as US $ 100 million to as high as US $ 300 million annually. Part of
the reason for this broad divergence probably lies in how individual
competitors choose to define this business.
For example, one large HVDC project involving series
capacitor banks and other installations can absorb a huge amount of metal oxide
devices, sometimes worth on the order of US $ 10-20 million. However, often
this business is most accessible only to those arrester suppliers who are also
the electrical industry giants awarded design and procurement responsibility
for the entire project.
