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Utilties Communicate Via Fiber-Optic Cable.

It's unique in Iowa and perhaps the nation: The new Iowa Gas headquarters relies on fiber-optic cable for almost all of its communications to the outside world.

The Iowa Resources subsidiary was recently formed as a separate corporation after decades of simply being a division of Iowa Power and Light Company. With the separation came a move to new headquarters in Des Moines, a mile from Iowa Power's headquartes. Because some data and communication services are still contractually handled by the electric company for the gas company, sophisticated communication links were needed between them.

Before the turn of the century, Iowa Power's predecessor electric companies were among early pioneers of underground electric-distribution systems, with installations in the downtown area. Expansion and upgrading of this system over the years left a natural opportunity for easy installation of fiber optics.

So now, Iowa Gas is served by a 1.2-mile, eight-fiber cable from the Iowa Power headquarters. A second leg of eight-fiber cable runs another one-third of a mile from the gas company's headquarters to its Des Moines work center.

This multi-fiber system handles several communication needs. An ITT T2 fiber head-end is used on a fiber pair at all locations. TWo of the four T1 channels are dedicated to ITT D448 PCM channel banks to provide 48 analog channels. These are used to control 23 mobile repeater stations, other analog microwave interconnections with Iowa Power's microwave system, and telephone tie lines. The other two T1 channels are used to connect General DataComm's T1 Megamux statistical data multiplexers between the three locations.

Another fiber pair is dedicated to a 40-megabit Network Technology hyper channel between the Iowa Power and Iowa Gas headquarters. This channel carries IBM data traffic between the two.

A fiber pair between the gas company offices and its work center use Fibronics units to extend 32 IBM channels to the work center. Still another pair of fiber will be used to provide T1 interconnections with the new Northern Telecom SL1-M at Iowa Gas and the soon-to-be-purchased Iowa Power PBX.

The system was entirely engineered and installed by the telecommunications department of Iowa Power. Says Telecommunications Manager Ron Johnsen: "We're very satisfied with the performance of the fiber-optics system. For more than a year, it's been providing reliable links for the data, two-way radio, microwave interconnection and telephone tieline needs of Iowa Gas."

Pull Wires Allow Splice-Free Run

The 1.2-mile fiber was pulled as a single, unspliced length. This created a few problems, because it was not an inline route. To solve this problem, pull wires were installed between manholes. A pulley was installed in each manhole along the way. The fiber was then pulled in from the middle of the path. When the first half of the cable pull was completed, the balance of the fiber cable was unspooled into a figure eight in a crawl space beneath a bridge crossing the Des Moines River. The second half of the pull then proceeded from that point.

"The strength of the fiber bundle and its forgiveness of abuse are unbelievable," says Johnsen. "We had to use a truck to pull a section of fiber that became wedged between two points, and we assumed we had sacrificed that length of fiber."

But testing found that each of the eight fibers was intact and still met the specifications of the manufacturer at the time of shipping. The cable was connected into the system, and is still in use.

A tight, buffered cable was used; and because there were no splices, only connectors needed to be installed for the fiber cable to be operational.

This wasn't the first fiber-optics venture for Johnsen and his staff. In the fall of 1982, they installed the first fiber-optics cable in Des Moines.

Taking advantage of the underground electric-distribution ductwork made this newest task relatively easy for Iowa Power's telecom personnel. Johnsen has shown the installation to representatives of other area companies that may be able to benefit from a similar application. The benefits have been proven to Iowa Power, which plans more fiber installation in the future to meet growing communication needs both in and out of its 5600-square-mile service area.
COPYRIGHT 1985 Nelson Publishing
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1985 Gale, Cengage Learning. All rights reserved.

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Publication:Communications News
Date:Aug 1, 1985
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