Input and distribution devices
Input (VU) or input distribution devices (ASU) are used to connect internal electrical networks of electrical installations to external power cable lines, as well as for the distribution of electrical energy and protection against overload and short circuit of output lines.
The input device also aims to differentiate the responsibility for the operation of the electrical networks between the personnel of the city network and the personnel of the user. After the input device, the electrical networks are under the control of the user. When powered by a single cable from low-power electrical installations belonging to the 3rd category of continuous power supply, three-pole input boxes of the BPV type for currents of 100, 250, 350 A with one block "Fuses PN-2 and switch. Y3700 boxes with one three-pole automatic switch of the A3700 series for currents of 50-600 A are also used. For three- and five-story residential buildings, cabinets of the SHB series are used as input devices.
Input and distribution devices for public buildings
For public buildings, high-rise residential buildings and small businesses, ASU input-distribution devices, made in the form of shields with one-sided or two-sided service, are used. Each input distribution device is complete with input and distribution panels or factory-made cabinets. In large cities, enterprises of electrical installation organizations develop and implement their own design series of ASP.
Introductory panels are made of the following types: VR, VP, VA. The equipment of the guide panels is designed for rated currents of 250, 400 and 630 A.
On VR-250 input panels for 250 A currents, PN-2-250 fuses, a P switch or RP series switch is installed. RB-series switches and PN-2-400 fuses, RB-series switches and PN-2-630 fuses are installed on the VP-400 and VP-630 entrance panels, respectively. An A3726 series circuit breaker for a rated current of 25 A is installed on the VA panels.
Switchboards are produced of the following types: switchboards with automatic outgoing line switches, switchboards with automatic control of stairwell and corridor lighting, switchboards with an accounting department. A37, AE20, AE1000 and AP50B series automatic switches, PML series magnetic starters, RPL intermediate relays and PV, PP package switches are installed in the distribution panels.
When assembling the ASU, the input and distribution panels of one input are located next to each other. ASU panels are produced by the manufacturer as individual panels with installed devices and devices, as well as connecting wires between the panels.
The figure shows a schematic diagram of one of the input panels with a single input switch.
Due to the wide variety of schemes of input and distribution panels VRU-UVR-8503, each ASU can be assembled according to the given electrical circuits for powering internal networks of buildings.
Schematic of an input panel with an input switch: 1 — meters, 2 — current transformers, 3 — power meter, 4 — anti-interference capacitors, 5 — fuse, b — switch, 7 — cable sleeve, 8 — circuit breaker, 9 — lamp with a filament
Input and distribution devices for industrial plants
In large enterprises that consume significant power, input and distribution cabinets and prefabricated panels of the SCHO-70 series are used as input and distribution devices. They are also used at substations in 0.4 kV switchgear. Structurally, they can be one-way or two-way services. The entrance panels have ABM series fused circuit breakers or circuit breakers, and the distribution panels have A37 series fused circuit breakers or circuit breakers.
Panel panels for one-way service are installed directly against the wall of the electrical room. They are served from the front. Panels of double-sided service panels are called single or free-standing and are located at a distance of at least 0.8 m from the wall.
One-way service panels require less space for their installation and maintenance than two-way service panels. In addition, they are more economical, but double-sided service panels are more convenient to work with.
In addition to panel panels, factories produce input-distribution and distribution panels assembled from separate blocks: fuse, switch, fuse, automatic machine, meter.
The premises of the input-distribution devices (the switchboard) are located in convenient places, where only service personnel have access. Gas pipelines should not pass through the switchboard, and other pipelines should be without connections, valves, valves. It is allowed to install ASU not in special rooms, but on staircases, in corridors, etc., but at the same time, the cabinets must be locked, the handles of the control devices must not be removed or removed. It is not allowed to install ASP in wet rooms and in places subject to flooding.
Read also: Requirements for entrance devices, distribution points and panels for group lighting