An Indian state is challenging in court a decision by the federal power regulator to allow utility Adani Power Ltd to raise tariffs, dealing a potential blow to a key sector struggling with chronic losses and erratic fuel supplies. The case filed by the northern state of Haryana underscores the ability of local politics to derail a federal decision that was hailed by power companies as a step toward ending electricity shortages that sap the competitiveness of businesses in India, hobbling economic growth. Haryana is home to the business hub of Gurgaon, where companies rely on costly generators to avoid major and frequent blackouts. Microsoft Corp, Google Inc and agribusiness giant Cargill Inc are some of the multinational firms based there. State power minister Ajay Yadav told Reuters his government had filed a challenge against an April ruling by the Central Electricity Regulatory Commission (CERC) that paved the way for Adani Power to increase the price at which it sells electr