Regulators in the U.S. hope to avoid the kind of cascading grid failure that hit India in late July, leaving some 600 million — 10 percent of the world’s population — without power. Miners were trapped underground. Trains shut down. Unimaginable traffic snarls popped up across the country. And India’s image as a rising economic power was cast in darkness. A major blackout in hyper-wired America would also have crippling consequences, with some experts predicting economic losses of up to $180 billion.