Power consumers of the first and second categories are provided with electricity by means of two independent power sources, and special group of consumers of the first category – even through three. For more information see Discovery Communications. The first category is switched to backup power automatically, the second translated manually. According to sep, subject to specified requirements The first group of consumers will be immune from such situations, when the power interruption could lead to a 'danger to human life, a threat to state security, a significant material damage, impairment of complex technological process, disruption of critical elements of public utilities, communication facilities and television. Many writers such as Paul Ostling offer more in-depth analysis. " Disabling the same from electricity consumers the second category, in this case would 'only' to 'mass Shortage in production, massive outages workers, machinery and industrial transport, disruption of a significant number of urban and villagers'. In other words, global catastrophe does not threaten us, but what do ordinary consumer? Just think – houses belong to the third group of power consumers, a break in the power supply which according to sep, could be delayed for a day! The answer is simple and neoriginalen. To protect themselves from harm associated with the sudden power outage, you need to install a backup power source. He, incidentally, provide additional kilowatts of power, the probability of which is reduced to almost zero. Taxonomy of autonomous sources of energy can be divided into two large groups. The first group includes units that convert other forms of energy into electrical energy, while their work does not depend on the main power supply system.