Powering down wears on equipment
JOHNSTON, IOWA: I believe one of the most challenging elements of the conversion to terrestrial DTV is keeping the analog system alive until the necessary hardware is installed, and a critical mass of homes has made the conversion.
In previous columns, I wrote in glowing terms about the cooperative partnership between the Cedar Rapids ABC affiliate, KCRG, and Iowa Public Television for sharing tower, antenna and transmission line. That project has been completed and is a tremendous success for both stations. However, there is always a yin associated with yang, and in this case the yin is our analog system.
Like everyone else, IPTV has had to deal with budget cuts. We eliminated discretionary spending. We eliminated unfilled positions and left vacant positions open. Over the last couple of years, we cut overnight operations to reduce power consumption. On paper, this looks good, but there were tradeoffs.
DOLLARS AND SENSE
The first and most obvious was educating non-technical people about the concepts of load factors and demand charges from power companies. In preparing our operating budgets for DTV facilities, we initially designed our systems and budgets based on 24/7 operation. For example, at our Des Moines DTV facility, a 100-percent load factor equates to about 4.9 cents per kilowatt hour. A 90-percent load factor means 5.2 cents per kWH, and at 80-percent load factor, we're looking at 5.6 cents per kWH.
Below 80 percent, demand charges start to increase the costs. At eight hours a day, at about a 33-percent load factor, we'd pay about 11.5 cents per kWH, or twice what we would pay at an 80-percent load factor.
Our existing analog power consumption is no different. The law of diminishing returns needs to be considered as part of the operating strategy. This is, however, a manageable problem, and can be calculated with the help of the power company. It is made more complex for IPTV since we have a statewide network of nine transmitters and are dealing with a number of different power companies, each of which has its own unique rules and rates.
A more troubling, and ultimately more catastrophic problem, is what has happened in the on-and-off cycling of the old transmitters. Since this process started, we have seen a marked increase in transmitter outages. Not all of them are serious, but as we expected, the majority occurred in early mornings when the transmitters were first turned on.
About 48 percent of the outages occurred within three hours of turning the transmitter on. Twenty percent occurred at sign-on, so there's a price for shutting down and powering back up.
We all know that things electrical work better if they are left on.
Mechanical issues also crop up. Our analog station in Waterloo recently endured several outages related to transmission line burnouts. The temperature cycling on the old RCA Caplock transmission line and the bullets started to wreak havoc. At the end of May, we had a serious burnout. As a result, we've been under a special temporary authority (STA) to operate at 50-percent power.
It reached the point where we decided to replace the inners on the existing line. Replacing the inners on a 28-year-old transmission line is not simple, particularly since we had to have the line manufactured. Due to problems with the manufacturing, the project was delayed, but work finally started Oct. 13. Unfortunately, there were a couple of minor injuries at the site and the crew had to shut down. The plan was to be back on the tower right after Thanksgiving.
The old transmission line decided not to wait. We had yet another burnout just before Thanksgiving. Couple that with late November weather in Iowa, and work on the tower was delayed until Dec. 2. Adding insult to injury, all of the burning molten metal from the more recent burnout fell through the new inners. We ended up with a short at the bottom elbow and became concerned about debris accumulation on the insulator discs. Consequently, the crew was instructed to break all the new connections and clean them. That process was scheduled for second week of December. In the meantime we operated the station at 25 percent power with our fingers crossed.
CRAPSHOOT
So what have we learned? When it comes to saving money, shutting down can be a crap shoot. At most of our sites, we've seen some increase in outages, but not significant cost increase from parts. Then again, one site like Waterloo can eat all the savings and then some. I don't think I'll ever accept another recommendation to replace the inners of old transmission line.
At our site in Red Oak, we did it as part of the new dual-band antenna. We had some manufacturing issues there as well. However, it made more sense at Waterloo, since the line was analog-only and will be decommissioned when we shut off, but in Red Oak we're going to live with the old-style line and its associated problems for another 25 years. As I said earlier, there is a balance in the universe. In Einstein's terms, nothing is gained or lost, it merely changes from matter to energy back to matter. The trick is to make sure that you're not standing under the tower when the matter that was your transmission line briefly turns to energy and then back to melted matter.
