Input-distribution devices (ASUs) are designed to connect internal power networks and electrical installations to external power sources and high-voltage cable lines. But the main functions of these devices are as follows: distribution (which is laid down in the name of the unit) of incoming electricity between isolated consumers and protection of lines from overloads, short circuits and other similar troubles.
In other words, the input-distribution device also serves to ensure electrical safety of high-voltage facilities and equipment. This is the most important destination of the ASU. In addition, such a switchgear delimits the responsibility for the operation of high-voltage lines between the personnel of urban electric networks and the consumer, since it can immediately be understood who is responsible for the accident or equipment failure. And all because the input-distribution device serves as a kind of watershed, a sort of border, on the one hand of which is the consumer’s area of responsibility, and on the other hand, employees of urban electricity networks. This approach is also a kind of guarantee of uninterrupted power supply of a large number of autonomous consumers, including not only residential apartment buildings, but also large enterprises that require large capacities and stable operation of the equipment.
For power supply using a single cable of small electrical installations, which belong to the third category of uninterrupted power supply, it is advisable to use a three-pole input-distribution device of the BPV type, designed for a current of one hundred to three hundred and fifty amperes, with one safety block and a switch. To ensure the stable and stable operation of such equipment, sometimes distribution boxes of the YAZ700 series are used, equipped with a three-pole circuit breaker and designed for currents of 500-600 amperes.
For power supply of residential buildings up to five floors, an input and distribution device of the type is installed. Of course, residential buildings of high storeys, public buildings and small-scale enterprises require completely different capacities. At such facilities, ASUs are usually used, which are structurally made in the form of switchboards for one- or two-way service. Any device of this type consists of an input and distribution panels. It can also be a factory-made cabinet.
In general, there are countless different models of such devices, since in almost all major cities, electrical installation companies develop their own design solutions, produce their own models and series of ASUs. Often, taking into account the specifics of a particular facility, where this equipment will be used.
For large plants and enterprises that differ in the consumption of colossal energy capacities, SchO-70 series input and distribution cabinets are provided. They are also used in energy-intensive facilities such as substations. Devices of this type, designed for power exceeding 0.4 kW, are equipped with special knife switches with fuses or automatic machines of the AVM and A37 series. Structurally, they can consist of individual blocks assembled at the installation site. The panels of such devices are installed directly at the walls of the electrical rooms and are serviced from the front side. The electrical switchboards themselves, in accordance with safety requirements, should be located in a convenient place where only the employees serving them have free access.
Passage through such premises of gas pipelines and other utilities is not allowed. In some cases, it is allowed to install such high-voltage equipment in the corridors, on the stairwells. But at the same time, the cabinets should be securely locked, and the control handles should not be brought out or they should be made removable. Inadmissible installation of such devices in rooms of high humidity, as well as in places prone to flooding.