As we go to press, the earthquake in Soviet Armenia is es-timated to have killed some 60,000 people. Whatever the true number, it is now increasing by secondary causes: among others by epidemics, lack of medical facilities, fires, and lack of electric power.
American utilities have learned much in recent earthquakes, among them those of San Fernando, Calif., 1971, Mexico City 1985, Palm Springs, Calif., 1986, and Whittier, Calif., 1987.
Of these, by far the greatest was the 1985 Mexico disaster, with 9,000 people killed in September 1985 by an earthquake measuring 8.1on the logarithmic Richter scale, followed by a Richter-7.8 aftershock 36 hours later. (This was two Richter-orders higher than the Armenian quake.) Yet Mexican Light & Power Co. earned international respect by restoring power to its 3,200,000 customers in only 72 hours.
An electric distribution network consists of "feeders" or high-voltage lines directly from the generating station to the substations, where the voltage is transformed to a lower value. It may then be routed through transmission lines to further substations, and the final substations distribute the power to the consumers in their area.
In Mexico, 51 feeders were knocked out of service, as were 270 of the city's 629 distribution lines. Ten substation transformers were put out of service. Some of these, weighing several tons, were thrown off their bases. But this, of course, emerged much later, for the two first casualties in a disaster are usually information and communication
¾reduced to battery-operated radio-liaison. Interestingly enough, Mexico City's success was in part due to dis-carding a contingency plan authorizing the army to coordinate municipal, utility and medical groups; what worked was an im-provised system of a coordinator (one person) with liaisons to groups repairing the power network, attending injured and exhausted workers, supplying equipment and material, and taking care of other logistics, respectively.One of the main lessons in Mexico was the importance of mobile generators of 30 to 300 kW, for hospitals (US hospitals are always equipped with them), field hospitals and for rescue teams to provide illumination and to drive power tools.
In California, the comparative density of the power network sometimes enables the distribution system to bypass the damaged areas. For example, in the 1987 Whittier earthquake (Richter 5.9), service was resumed within a few hours (on a 105øF day with heavy air conditioning demand), although it took many months to repair the damage. The long-lasting damage was mostly done to por-celain insulators used for conductor supports, lightning arresters, transformers, and circuit breakers shaken to the ground.
The quickly repaired damage included that to transformers in substations. They have a safety switch that disconnects the trans-former when an electrical short causes the pressure of the cooling liquid to rise suddenly. In an earthquake the transformers are rocked, and the resulting wave motion causes the pressure to rise and the switch to be activated, even if no real damage has occurred.
But the earthquake also loosened many oil bushings, causing the oil to leak out. That it did not then catch fire in Whittier was a mat-ter of sheer luck. As I have pointed out before [AtE Nov 85], the cooling liquid used to be incombustible PCB, which has been banned by the EPA's arsonists who are more interested in image-polishing carcinogen hunts than environmental protection.
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Vol. 16, No. 5
Newsletter: Access to Energy Newsletter Archive Volume: Issues Issue/No.: Vol. 16, No. 5 Date: December 01, 2004 02:20 PM Title: The privilege of irresponsibility
Copyright © 2004 - Access to Energy Newsletter Archive
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