Shenhai Explosion-Proof
Explosion-proof distribution boxes, vital terminal distribution equipment in power systems, play a crucial role in controlling and protecting industrial electricity in hazardous environments. Given their ubiquity, let’s delve into the installation and wiring of indoor distribution boxes today.
1Process Flow for High and Low Voltage Explosion-Proof Distribution Boxes:
Foundation acceptance.
Unboxing and equipment inspection.
Secondary transportation of equipment.
Transformer placement.
Accessory installation and wiring.
Handover test.
Pre-operation inspection.
Trial operation.
Completion and acceptance.
2. Installation of High and Low Voltage Explosion-Proof Distribution Boxes:
Before installation, the control room should be ready, with all interior work completed, and the environment clean and safe.
A. Installation and Fixation of High and Low Voltage Explosion-Proof Distribution Boxes:
1. After the boxes arrive on-site, inspect for deformations, paint loss, completeness of instruments, accessories, manuals, etc., and record the findings.
2. Place the switchboxes on the foundation steel as per the layout plan. First align the two ends, then stretch a line at two-thirds height from the bottom, aligning each box to this line. Adjust using 0.5mm shims; a maximum of three shims per spot.
3. After positioning and aligning, fix the boxes using bolts as per the holes. Connect boxes and side panels with galvanized screws. Weld high and low voltage switchboxes to the reserved angle steels firmly. Cover the visible part of the cable layer with checkered steel plates. Both front and rear of the boxes should be covered with 1200mm x 10mm insulation.
4. Ensure neighboring boxes’ top level difference is within 2mm, and the overall difference doesn’t exceed 5mm. The unevenness between two adjacent boxes should not exceed 1mm, and the total unevenness not more than 5mm. The gap between boxes should not be more than 2mm.
5. After positioning the equipment, re-tighten internal fasteners and check, especially at conductor connection ends. Once wiring inside the box is complete, clean the interior with a vacuum cleaner, maintain cleanliness inside and out, and correctly label equipment and circuit numbers.
After installing the distribution box, install the cable tray above it. The box’s cable entry holes should be pre-reserved by the supplier. Seal the cable layout upon completion. Connect the tray to the ground bus bar inside the box with a dedicated grounding wire. Use rubber plates to connect the tray to the explosion-proof distribution box, protecting wires and cables. See the diagram for the connection between the tray and the box.
B. Secondary Circuit Wiring of High and Low Voltage Explosion-Proof Distribution Boxes:
The factory should complete the secondary circuit wiring and relevant tests before shipping. Upon arrival, organize acceptance under the supervision of the client’s engineers and supervisors. Ensure completeness of technical documents, packaging, and sealing, and the integrity and reliability of all components and wiring.
After installation, perform insulation tests on each box’s secondary circuit using a 500V insulation tester, ensuring readings exceed 1MΩ.
Use multi-strand soft copper wires or cables for all secondary control circuits. Use appropriate terminal blocks and crimp with a special crimping tool after soldering with neutral flux.
C. Handover Tests of High and Low Voltage Explosion-Proof Distribution Boxes:
Details of handover tests are described in the commissioning and energizing sections.
D. Additional Requirements for High and Low Voltage Explosion-Proof Distribution Boxes:
1. Drawer-type switch cabinets must meet the following requirements:
a. Drawers should move smoothly without jamming or collision.
b. Dynamic and static contacts should align and connect tightly.
c. Mechanical or electrical interlocks must operate correctly, ensuring isolation contacts open only after the circuit breaker trips.
d. Ground contacts between drawers and the cabinet should be tightly connected. When pushing a drawer in, its ground contact should connect before the main contact; the reverse applies when pulling out.
2. Check design drawings before insulation testing of the secondary circuit in the distribution box. Remove fragile components beforehand.
3. Ensure the paint is intact and undamaged during installation, with complete interior lighting.
4. All equipment casings in the substation must be well-grounded.
Generally, professional electricians should handle the wiring of explosion-proof distribution boxes, as they possess the necessary skills and safety equipment. In non-urgent cases, it’s better not to repair or install distribution boxes yourself, as electricity requires caution and care. Especially when wiring indoor distribution boxes, never forget to turn off the main switch at home for safety.