In the suburbs and countryside the grid is clearly visible—those bare overhead high-tension wires and power poles and service lines running into your house. When a line goes down, there's little difficulty finding and fixing the problem. In many cities, though, like New York, the elec¬tricity flows underground, in insulated cables. Because the insulation degrades after time and suffers groundwater damage, resulting in shorts and loss of service, power companies rely on double or even triple redun¬dancy in the grid. When substation MH-12 went down, the computer automatically began filling customer demand by rerouting the juice from other locations.
"No dropouts, no brownouts," another tech called.
Electricity in the grid is like water coming into a house from a sin¬gle main pipe and flowing out through many open faucets. When one is closed, the pressure in the others increases. Electricity's the same, though it moves a lot more quickly than water—nearly 700 million miles an hour. And because New York City demanded a lot of power, the voltages—the electrical equivalent of water pressure—in the substations doing the extra work were running high.
But the system was built to handle this and the voltage indicators were still in the green.
What was troubling the supervisor, though, was why the circuit break¬ers in MH-12 had separated in the first place. The most common reason for a substation's breakers to pop is either a short circuit or unusually high demand at peak times—early morning, both rush hours and early eve¬ning, or when the temperature soars and greedy air conditioners demand their juice.
None of those was the case at 11:20:20:003 a.m. on this comfortable April day.
"Get a troubleman over to MH-Twelve. Could be a bum cable. Or a short in the—"
Just then a second red light began to flash.
Another area substation, located near Paramus, New Jersey, had gone down. It was one of those taking up the slack in Manhattan-12's absence.
The supervisor made a sound, half laugh, half cough. A perplexed frown screwed into his face. "What the hell's going on? The load's within tolerances."
"Sensors and indicators all functioning," one technician called.
"SCADA problem?" the supervisor called. Algonquin's power empire was overseen by a sophisticated Supervisory Control and Data Acqui¬sition program, running on huge Unix computers. The legendary 2003 Northeast Blackout, the largest ever in North America, was caused in part by a series of computer software errors. Today's systems wouldn't let that disaster happen again but that wasn't to say a different computer screwup couldn't occur.
"I don't know," one of his assistants said slowly. "But I'd think it'd have to be. Diagnostics say there's no physical problem with the lines or switchgear."
The supervisor stared at the screen, waited for the next logical step: letting them know which new substation—or stations—would kick in to fill the gap created by the loss of NJ-18.
But no such message appeared.
The three Manhattan substations, 17, 10 and 13, continued alone in providing juice to two service areas of the city that would otherwise be dark. The SCADA program wasn't doing what it should have: bringing in power from other stations to help. Now the amount of electricity flow¬ing into and out of each of those three stations was growing dramatically.