Английский

Перевести: Over the years, since the introduction of electric traction on railways, the rule has generally been that AC is used for longer distances and on main lines and DC for shorter, suburban or metro lines. DC gets up to 3,000 volts, while AC uses 15,000 to 50,000 volts. Until recently, DC motors have been the preferred type for railways because their characteristics were just right for the job. They were easy to control, too. For this reason, even trains powered from AC supplies were usually equipped with DC motors.