The North Dakota Public Service Commission (PSC) has directed Northern States Power Co., a local distribution company (LDC), to eliminate three "nongas" cost components from its purchased-gas...
Service to the 9's? Power Quality in a Tech-Wreck World
process. They are so responsive that they create problems, depending on how they've been programmed. They're used in petrochemicals, pulp and paper, textiles, and general manufacturing. And in the automotive industry for sure, with all the robotics they have.
"A PLC might require an adjustable drive to shut down if it senses a 50 percent voltage sag. But sometimes these controllers are too sensitive. They might come pre-programmed, or it could be the guy on the plant floor who reprograms the PLC and sets the tolerance too tight."
But even though manufacturers can buy power quality equipment off-the-shelf, including "ride-through" devices that allow a plant or process to work right through a voltage sag, Sitzlar believes there always will be a need for custom consulting services on power quality.
"Let me give you an example about really understanding the problem, as opposed to just applying a band aid."
"There was a company making tungsten filaments for light bulbs. They take huge bars of tungsten, run them through a press, and draw the filament out at the other end, as a small, hair-like wire that runs around a spool. But this plant had a problem. The wire was breaking, and they had to keep shutting everything down and restarting the process.
"They had several consulting companies come out to try to fix the problem. The first consultant proposed a SMES installation (Superconducting Magnetic Energy Storage) to support the entire manufacturing facility. It would address instantaneous problems-about a half-cycle of the input wave, to get you through the instant of the momentary disturbance. But that could have cost millions. "The local utility offered a different solution. They said, 'let's consider a parallel feeder as a backup to make the power more reliable.' That would increase reliability, but also could have cost a million dollars.
"So then the manufacturer asked for a third recommendation, and they called us in. And as we saw it, the problem wasn't the entire facility, but only the take-up spool. Every time there was a momentary sag on the line, the spool would pause for a microsecond, and then when the power was normal again, it would try to speed up and catch up, and it would overspin and snap the wire.
"So we recommended installing a small spring (a $5 fix) to serve as a shock absorber. The spring would take up any change in tension, rather than force all the tension on the filament itself."
Remaking the Grid
From a utility perspective, where is the economic tradeoff? At what point does it become cheaper for utilities to focus on distribution network solutions, rather than work out a remedy at the customer's facility? Winnerling acknowledges the much-touted idea of "the "premium park"-upgrading the grid in a neighborhood filled with high-tech offices.
"We have something called a 'UPS substation' (uninterruptible power supply). It comes equipped with a huge battery bank-literally hundreds of batteries-just to allow the utility to keep a few seconds of power on, at a high cost. But in some substations, in some neighborhoods, providing that premium power