(3) Process description of concealed installation of distribution box: determine the opening position and make holes; Fix the four corners of the concealed box to ensure that the height of the concealed box meets the requirements and is level with the wall; If the back of the box can only be plastered, the general contractor needs to hang steel wire mesh behind the box before plastering; If several conduits into the box are installed side by side in a concealed manner, the steel wire mesh shall also be hung at the pipe groove and then plastered.
Measure the insulation resistance of low-voltage electrical appliances, connected cables and secondary circuits: the insulation resistance of motors, electric heaters and electric actuators shall be greater than 0.5m Ω.
(2) Description of open installation process of distribution box: when the plastering of wall and column surface at the installation place on the ground is not completed, the angle steel support shall be fixed with expansion bolts after the box, and then the box shall be fixed on the angle steel support with galvanized bolts.
3.
The starting times and interval of AC motor under no-load state (without feeding) shall meet the requirements of product technical conditions; If there is no requirement, the time interval between two consecutive starts shall not be less than 5min, and the motor shall be started again when it is cooled to normal temperature..
2 electrical equipment test and commissioning (1) process description of low-voltage electrical equipment test contents: the test items of low-voltage electrical appliances shall include the following contents: 1.
If there are incoming and outgoing cables, a foundation pit shall be reserved at the bottom of the cabinet to meet the requirements of cable bending radius.
Connect the pipe into the cabinet and lock the pipe end.
The release used for low-voltage apparatus shall be set according to the use requirements; Measure the DC resistance of the resistor and rheostat.
1.
Verification of voltage coil action value: the pull-in voltage of the coil shall not be greater than 85% of the rated voltage, and the release voltage shall not be less than 5% of the rated voltage; The closing coil for short-time operation shall be within 85% ~ 110% of the rated voltage, and the shunt coil shall be able to work reliably within 75% ~ 110% of the rated voltage.
The construction quality is directly related to the appearance and use function, which is particularly important in the excellence evaluation.
Check the action of low voltage apparatus.
According to the position of the connected bridge and the layout of components in the cabinet, holes shall be opened.
(4) Installation process description of hollow block wall and aerated concrete block wall: after plastering the wall, fix the four corners of the box on the hollow core wall with galvanized screw rod.
The allowable deviation of perpendicularity of cabinet, panel, table, box and panel installation is 1.5 ‰, the joint between them shall not be greater than 2mm, and the deviation of panel surface in rows shall not be greater than 5mm.
Building electrical engineering is a very important divisional project in construction engineering.
The circuit identification in the box shall be correct, clear and complete.
5.
AC withstand voltage test of low-voltage apparatus, connected cable and secondary circuit: when the insulation resistance is greater than 10m Ω, shake it with 2500V megger for 1min, and there shall be no flashover and breakdown; When the insulation resistance value is 1 ~ 10m Ω, conduct 1000V AC power frequency withstand voltage test for 1min, and there shall be no flashover and breakdown.
(5) Process description of electrical conduit entering the box: the box shall be perforated with a hole opener, one set for each hole, and the pipe diameter shall be consistent with the knock down hole of the box (box).
Installation of complete set of distribution cabinet, control cabinet (panel and console), power and lighting distribution box (panel) and control cabinet (1) installation process description of complete set of distribution cabinet: the exposed electrical cabinet in the basement shall be installed on the section steel support to prevent the condensation water on the wall from entering the box.
(7) Description of wiring process in the box: the identification in the distribution box shall be clear, the identification plates of PE row, n row and each circuit shall be accurate, the cables and wires shall be arranged in order, and the inlet holes shall be sealed tightly.
5.
The size and spacing of holes shall match the protective opening.
2.
(2) Process description of low voltage electrical equipment test and commissioning procedure: the test and commissioning of low voltage electrical power equipment shall be carried out according to the following procedures: 1.
If the knock out hole is large and the pipe diameter is small, it can be padded tightly with iron sheet gasket or leveled with mortar and gypsum, and the hole shall not be exposed.
The AC power frequency withstand voltage test of complete power distribution (control) cabinet, panel, table, box and panel and the action test of protective device shall be qualified before power on.
The motor shall be powered on for test, and the steering and mechanical rotation shall be checked for abnormalities; For the motor that can be tested for no-load operation, the time is generally 2H.
When several open boxes are placed side by side, the installation height of the box shall be determined according to the principle that the maximum top elevation of the box shall not exceed 2.3m and the top or bottom of all boxes shall be flat.
3.
When the steel pipe enters the box, a 4.2mm hole shall be reserved near the steel pipe for the grounding wire to enter the box.
Taking the project standardization practice of the third company of China Construction Fifth Bureau as an example, this paper comprehensively summarizes the construction technology of building electrical engineering for your reference and study.
One cable has one hole.
The test can be carried out only after the accessible bare conductor grounding (PE) or neutral (pen) connection of the equipment is completed and passed the inspection.
2.
The control circuit simulation action test is qualified, the turning or manual operation, the rotation or action of the electrical part and the mechanical part are consistent, and the no-load test run can be carried out only after inspection and confirmation.
The electronic components in the circuit of cabinet, panel, table, box and panel shall not participate in AC power frequency voltage withstand test; AC power frequency withstand voltage test is not required for circuits of 48V and below.
Galvanized hexagon bolt M10 shall be welded on the inner side of the channel steel × 25 for grounding.
4.
The allowable deviation of foundation section steel is 1mm per meter, 5mm in total length and 5mm in total length.
When mineral cables or single core plastic insulated cables enter the cabinet, each incoming hole between a group of cables shall be connected with each other with a seam of 1-2mm.
Generally, 10# channel steel is used as the foundation under the cabinet.
(6) Process description of cable tray entering the box: the cable tray is connected by holding feet outside the box.
Record the no-load current and check the temperature rise of the body and bearing.
Lead the cable tray to the end of bvr-4 cabinet.
4.
When installing on the light partition wall, determine the opening position and make holes; After the light steel keel is decorated and installed, the concealed box body is fixed on the light steel keel with pull rivets or self tapping screws; The concealed distribution box cover is close to the wall, and the box (panel) coating is complete.
