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How to install the distribution box

2017-05-27  187

The installation position of low-voltage distribution box should avoid direct sunlight, splashing and moisture, and there is sufficient operation space in front. Regularly clean the equipment in the cabinet, check the wiring terminals, check whether each switch and contactor are in good condition and whether there is overheating inside. Regularly check the sealing performance of the distribution cabinet to prevent small animals from entering or internal condensation. For areas with high humidity, it is also necessary to equip with moisture repellents, dryers, etc. Check whether the installation position is firm without deflection and shaking.


(1) Equipment requirements

1) The appearance inspection of the cabinet (panel) body shall be free of damage and deformation, and the paint shall be intact. Internal inspection of cabinet (panel): electrical devices, components and insulating porcelain parts are complete without damage, cracks and other defects.

2) Before installation, check whether the number of distribution box is consistent with the installation position, and check its box number and circuit number according to the design drawing. The box door shall be grounded with soft copper braided wire and special wiring terminal. The wiring in the box shall be neat and meet the design requirements and the provisions of the acceptance code (GB50303-2002).


(2) Operating conditions

The civil engineering of the installation site of the distribution box should have the basic conditions that the internal painting is completed and the doors and windows have been installed. The embedded pipes and embedded parts shall be cleaned; The site has transportation conditions to keep the roads smooth and smooth.


(3) Location of distribution box: determine the location of distribution box and the actual equipment installation on site according to the design requirements, and snap lines and locate according to the overall dimensions of the box.


(4) Installation of foundation section steel

1) Prefabricate and process the foundation steel frame according to the requirements of the drawing, and do a good job of anti-corrosion treatment. Place the prefabricated foundation steel frame on the reserved iron parts according to the position marked on the construction drawing. After leveling and alignment, weld the foundation steel frame, embedded iron parts and gaskets firmly with electric welding. The top of the final foundation steel should be 10mm higher than the ground.

2) Grounding of foundation section steel: after the installation of foundation section steel, the grounding wire should be firmly welded with both ends of the foundation section steel. The welding surface is twice the width of flat steel, and then it should be reliably connected with the cabinet grounding bar. And do a good job of anti-corrosion treatment.


(5) Installation of distribution cabinet (panel)

1) Installation of cabinets (panels): the distribution cabinets shall be placed on the foundation steel one by one according to the layout of the construction drawing. The adjustment of the perpendicularity of the cabinet surface and side of a separate cabinet (panel) can be solved by adding sizing blocks, but not more than three pieces, and they are firmly welded. After each cabinet (panel) in a row is in place, the levelness of the cabinet and the deviation of the panel shall be adjusted to meet the provisions of the construction specifications.

2) The wall mounted distribution box can be fixed on the wall with expansion bolts, but the hollow brick or block wall should be embedded with dovetail bolts or fixed with split bolts.

3) The distribution box should be embedded, and the panel should be level with the wall after installation.

4) After the adjustment of the cabinet (panel), the cabinet body and the foundation section steel shall be fastened with bolts.

5) Cabinet (panel) grounding: each cabinet (panel) is separately connected with the foundation section steel. Copper wire can be used to reliably connect the PE row in the cabinet with the grounding bolt, and spring washer must be added for anti loosening treatment. Each cabinet door shall be reliably connected with PE row with copper braided wire.

6) The top of the cabinet (panel) is connected with the bus. Note that the bus should be fastened with a matching wrench as required, and the contact surface should be coated with neutral Vaseline. When connecting the busbar between cabinets, pay attention to whether the busbar is too close to other devices or shells, and pay attention to the correct phase.

7) Control circuit inspection: check whether the line is loose due to transportation and other factors, and tighten it one by one, and whether the electrical components are damaged. In principle, the cabinet (panel) control circuit is calibrated before leaving the factory. The circuit in the cabinet should not be adjusted privately. If any problem is found, contact the supplier.

8) After the control line is calibrated, each core wire is simmered into a circle and connected to each terminal board with galvanized screws, eye rings and spring pads. One terminal on each side of the terminal board is usually pressed with one wire, which can not exceed two at most, and eye rings are added between the two wires. Multi strand wires should be rinsed with tin, and no broken strands are allowed.


(6) Cabinet (panel) test adjustment

1) The high voltage test shall be carried out by a test unit approved by the local power supply department. The test standard conforms to the national specifications, the regulations of the local power supply department and the requirements of product technical data.

2) Test content: high voltage cabinet frame, bus, lightning arrester, high voltage porcelain insulator, voltage transformer, current transformer, various switches, etc.

3) Adjustment contents: overcurrent relay adjustment, time relay, signal relay adjustment and mechanical interlock adjustment.

4) Secondary control small wire adjustment and simulation test, tighten all terminal screws again.

5) Insulation test: use 500V insulation resistance test instrument to test the resistance of each circuit at the terminal board, and the resistance must be greater than 0.5m Ω.

6) If there are transistors, integrated circuits and electronic components in the secondary small line circuit, use a multimeter to test whether the circuit is connected.

7) Connect the temporary control power supply and operation power supply; Remove the phase line at the upper end of the fuse of the control and operation power circuit in the cabinet (panel) and connect the temporary power supply.

8) Simulation test: according to the requirements of the drawing, simulate the control, interlocking, operation, relay protection and signal action respectively, which are correct, sensitive and reliable.

9) Remove the temporary power supply and reset the removed power line.


(7) Conditions for power transmission operation

1) The installation work should be completed, and the quality inspection department should check that it is all qualified. All test items are qualified, and there is a test report.

2) Electroscope, insulating boots, insulating gloves, temporary grounding braided copper wire, insulating rubber pad, powder fire extinguisher, etc. for the test shall be prepared.

3) Check whether there are sundries left on the bus and equipment.

4) Do a good job in the organization of commissioning, and clarify the commissioning commander, operator and guardian.

5) Clean the dust in the equipment, transformation and distribution room and control room. Clean electrical appliances and instrument components with a vacuum cleaner.

6) The relay protection action is sensitive and reliable, and the control, interlocking, signal and other actions are accurate.


(8) Power transmission

1) After passing the inspection by the power supply department, the power supply will be sent to the building, and the power will be checked and the phase will be correct.

2) The installation unit switches on the incoming cabinet and checks whether the three-phase voltage of the voltmeter on the PT cabinet is normal.

3) Turn on the switch of the transformer cabinet and check whether the transformer is powered.

4) Close the incoming switch of the low-voltage cabinet and check whether the three-phase voltage of the voltmeter is normal.

5) Power on in the above order.

6) In the low-voltage contact cabinet, check the same phase at the upper and lower sides of the switch (the switch is not closed). Use a voltmeter or multimeter with a voltage range of 500V, and use the net measuring pins of the meter to contact the same phase of the two circuits respectively. At this time, the voltmeter has no reading, indicating that the two circuits are in the same phase. Check the other two phases in the same way.

7) Acceptance: after power transmission and no-load operation for 24h, there is no abnormal phenomenon, go through the acceptance procedures, and submit it to the construction unit for use. At the same time, technical data such as change negotiation records, product certificates, instructions, test reports, etc. shall be submitted.