number of failures that resulted in prolonged
Table 2. Summary of CMP transmission outages.
customer outages. The causes of all these
outages are summarized in Table 2. Post-
Cause of outage
Number of
occurrences
type insulators typically break from the dy-
namic load induced when ice unloads sud-
Trees
23
Broken post-type insulator
11
denly from the wire. In all other cases,
Broken crossarm
8
except the underground cable fault, ice-lad-
Conductor down
5
en trees and branches falling and leaning on
Broken pole
3
the wires initiated the damage that caused
Entire structure down
3
the outage. In eastern Maine, an ice-dam-
Underground cable fault
1
aged switch caused a nine-hour transmission
Miscellaneous (burnt pole, tap
outage in Eastern Maine Electric Coop's
burnt off, bus fault, broken
system that affected about 40% of its cus-
aerial, broken pin insulator)
5
tomers.
6.1.4 Communications
Our assessment of the wireless communication system in the storm-affected region indicates
a generally positive performance of the system as a whole. Major problems included insufficient
auxiliary generators to power all the sites that were without commercial power for an extended
period, difficulty in getting fuel to the sites with generators because of the trees blocking access
roads, and cracked dish and cellular antennas. In most areas problems were addressed relatively
quickly to regain some level of service. Successful solution of problems was accomplished by a
combination of the following:
1)
Auxiliary power sources, including batteries and generators
2)
Backup antenna sites
3)
System redundancy (alternate ways of bypassing off-line towers)
4)
Excellent cooperation within the industry
5)
Providers having an adequate parts inventory or the means to buy or borrow on short
notice.
To date we have confirmed the collapse of 8 broadcast and 10 two-way towers throughout the
storm-affected region (Table 3). We know of no communication tower failures in Vermont and
only one in New Hampshire. The WLNH-FM radio station lost its 245-ft-tall tower in Laconia
(Fig. 18a). The tower, a key station in New Hampshire's EAS system, also carried the antenna
for FM radio station WBHG, which was off the air for 11 days. The bottom half of the WEZQ
tower that failed in the storm is shown in Fig. 18b. At this site on Blackcap Mountain in East
Eddington, Maine, a dozen other towers withstood the ice storm. The locations of the confirmed
tower failures are shown in the map in Fig. 19.
On many of these towers very large ice accretion estimates are reported under Comments in
Table 3. A photo taken of the ice on the guys of the Coast Guard tower on Cadillac Mountain in
Acadia National Park supports the reported 8- to 10-in. ice diameter on a 1/4-in.-diameter guy.
The probable mechanism for the formation of the large ice accretions on towers on these moun-
taintop sites is discussed in Section 6.2.
Phone drops that were pulled off houses by falling trees and branches were the major prob-
lem for non-wireless phone systems. In contrast to electrical distribution wires that run along
27
Back to contents page
Previous Page
