Power boxes
It is customary to call power supply boxes with a switch, a switch and fuses, fuses, a switch, a switch and with a block with a fuse, designed for switching and protecting network lines with a voltage of up to 500 V, i.e. unlike conventional switches, power supply boxes allow to perform the functions of switching and protection at the same time.
The power supply box has a metal housing with a door inside which one of the above switching devices is mounted, in combination with or without fuses.
The power supply boxes are manufactured in protected, closed (dustproof), waterproof and explosion-proof versions.
Safety when servicing power supply boxes is provided by an interlock that prevents the box door from opening when the switch or block is on, and turning them on when the door is open.
The metal cases of the boxes are stamped and cast. The latter are located in power supply boxes, the implementation of which requires a reliable seal.
YABPVU Power Box
YABPV and YABPVU series power supply boxes
Fuse block boxes are widely used. They almost completely replaced the previously used circuit breaker and fuse boxes. One of the series of boxes with «fuse» blocks is the YABPV series — in a protected version, the other series — the YABPVU boxes in a closed (dustproof) version for alternating current networks with a voltage of up to 380 V. In these boxes, blocks of the BPV type are used (for closed-type YABPVU boxes, structurally slightly different from BPV blocks).
Boxes like YaABP, YaABPVU are designed for line protection and infrequent switching of electrical circuits. As knives in power supply boxes are used PN-2 series fuses (YABPVU -1M — for rated current 100A, YABP1-2U3 — 250A, YABPVU -4U3 — 400A).
Diagrams of inputs and outputs of boxes are shown in the figure. Entry or exit (as well as exit or entry) of no more than two lines can be made both above and below.
Diagrams of inputs in boxes of power series YABPV and YABPVU.
The cross-section of the lines, when made with aluminum wires, should not exceed: 3×50 mm2 + 1×25 mm2 for boxes YABPV-1 and YABPVU-1 and 3×120 mm2 + 1x60mm2 for boxes YABPV-2, YABPV- 4, YABPVU-2 and YABPVU-4.
Common types of YABPV and YABPVU power series boxes: a-box YABPV-1 and YABPVU-1, b-box YABPV-2, YABPV-4, YABPVU-2 and YABPVU-4.
The metal body of the box has three holes. Opening the. the facade is used to install the block. The openings at the top and bottom, intended for the introduction of wires, are closed with covers. The lids of the YaBPVU series boxes are sealed.
The boxes are installed in the following sequence; remove the block, remove the top and bottom covers and make holes in them for entering pipes.The lids are placed on the box and fixed on the wall.
The pipes are inserted into the holes of the covers and fixed in them with the help of adjusting nuts. The wires are tightened in the pipes, the ends are inserted, sufficient to connect to the terminals of the block, when the latter is completely removed from the box. The terminals are pressed into the ends of the wires. The block is brought to the hole and the tips are fixed (baited) on its clamps. The block is then inserted into the hole and fixed. Then, through the door of the block, the bolts of the brackets securing the tips are tightened with a wrench.
The housing of the power box is connected to the grounding grid. If the fourth wire is used for this purpose, then its connection to the body inside is carried out with the module removed.
YABPVU power box with open door
YaV3 series power supply boxes, which are another type of fuse block boxes, can be installed not only in AC but also in DC.
YAV3 type power supply box: a — general view of the box, b — YAV3 box with open door
A block with a sealed door is mounted inside a steel case, its handle is located on the right side of the box. Holes for entry and exit of wires are located at the top and bottom. Fittings are installed on the openings. The opening, which is not used for the entry or exit of wires, is closed with a flat flange and the fittings are not mounted on it.
The fuse holders in this box, as well as in the YaBPV series boxes, can be replaced with knives. In this case, the boxes can only be used for switching.
YAVSH type power supply box
Power supply boxes of the YAVSh series are designed to power mobile receivers. Mounted in boxes packet switch and a socket plug blocked in such a way that the possibility of removing the plug of the socket when the package switch is turned on, that is, disconnecting the circuit under load, is excluded.
