American Superconductor Corp., a maker of wind-turbine and power-grid electronics, posted a quarterly loss of $10.3 million, or 20 cents a share, vs. a loss of $37.7 million, or 74 cents, a year earlier. The Devens-based firm is looking to overcome the loss of Sinovel Wind Group, which contributed about 70 percent of its fiscal 2010 revenue and stopped taking shipments in 2011.