Islamabad, Jan 23 Pakistan faced a major power breakdown on Monday due to a "frequency variation" in the national grid, leaving millions of people in large parts of the country, including capital Islamabad and financial hub Karachi, without electricity. According to the Ministry of Energy, the system of frequency of the national grid went down at 7:34 am local time, resulting in the breakdown. “System maintenance work is progressing rapidly,” it tweeted.