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five. Installation of power distribution cabinet (panel)

1. Cabinet (panel) installation: According to the layout of the construction drawings, the power distribution cabinets should be placed one by one on the foundation steel in order. The vertical adjustment of the cabinet surface and the side of a separate cabinet (pan) can be solved by adding a shim, but it should not exceed three pieces and be welded firmly. After the rows of cabinets (pans) are in place, the levelness and panel deviation of the cabinets should be adjusted to meet the requirements of the construction specifications.

2. Wall-mounted distribution boxes can be fixed on the wall with expansion bolts, but dovetail bolts should be pre-embedded on the wall of hollow bricks or blocks or fixed by tension bolts.

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

4. After the adjustment of the cabinet is completed, the cabinet body and the basic section steel shall be fastened with bolts.

5. Cabinet  grounding: each cabinet  is connected to the basic steel separately. Copper wires can be used to reliably connect the PE row in the cabinet with the grounding bolts, and spring washers must be added to prevent loosening. Each cabinet door should be reliably connected to the PE row with copper braided wire.

6. Connect the top of the cabinet  to the busbar. Note that the busbar matching wrench should be used for tightening as required, and the contact surface should be coated with neutral petroleum jelly. When connecting the busbars between the cabinets, pay attention to whether the busbars are too close to other devices or the shell, and pay attention to the correct phase.

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

8. After the control wire is calibrated, simmer each core wire into a circle, and connect it to each terminal board with galvanized screws, eye circles, and spring pads. Generally, one terminal presses one wire on each side of the terminal board, no more than two wires are allowed, and an eye circle is added between the two wires. Multi-strand wires should be tinned, and no broken strands are allowed.

Six, cabinet test adjustment

1. The high voltage test should be carried out by a test unit approved by the local power supply department. The test standard complies with national regulations, local power supply department regulations and product technical data requirements.

2. Test content: high-voltage cabinet frame, bus bar, lightning arrester, high-voltage porcelain bottle, voltage transformer, current transformer, various switches, etc.

3. Adjustment content: adjustment of overcurrent relay, adjustment of time relay, signal relay and mechanical interlock adjustment.

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

5. Insulation test: Use a 500V insulation resistance tester to test the resistance of each loop at the terminal board. The resistance must be greater than 0.5MΩ.

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

7. Connect the temporary control power supply and operation power supply; remove the upper phase wire of the control and operation power circuit fuse in the cabinet, and connect the temporary power supply.

8. Simulation test: According to the requirements of the drawing, simulate the test 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 cord.

Seven. Conditions for power transmission operation

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

2. The electroscope, insulating boots, insulating gloves, temporary grounding braided copper wire, insulating rubber pad, powder fire extinguisher, etc. should be prepared for the test.

3. Check whether there is any debris left on the bus bar and equipment.

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

5. Clean the dust in equipment, power distribution room and control room. Use a vacuum cleaner to clean electrical appliances and instrument components.

6. The action of relay protection is sensitive and reliable, and the actions of control, interlock and signal are accurate.

Eight, power transmission

1. After passing the inspection by the power supply department, send the power supply into the building, and go through electrical inspection and correct phase calibration.

2. Turn on the switch of the incoming line cabinet by the installation unit, and check whether the three-phase voltage of the voltmeter on the PT cabinet is normal.

3. Close the switch of the transformer cabinet and check whether the transformer has electricity. 

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

5. Power on in sequence in the above order.

6. In the low-voltage contact cabinet, check the same phase on the upper and lower sides of the switch (the switch is not closed). Use a voltmeter or a multimeter with a voltage range of 500V, and use the two probes 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. In the same way, check the other two phases.

7. Acceptance: No-load operation for 24 hours after power transmission, no abnormal phenomenon, go through the acceptance procedures, and hand over to the construction unit for use. At the same time, submit technical materials such as change negotiation records, product qualification certificates, instructions, test reports, etc.

Nine, what are the requirements for the use environment of the distribution box

1. The altitude of the distribution box is generally required to be 1000m and below, which can ensure the normal operation of the box-type substation.

2. The ambient temperature it adapts to is generally between -25°C and +40°C to ensure the stable operation of the components of the box-type substation.

3. Generally, the wind speed should not exceed 35m/s.

4. The relative humidity of the air should generally not exceed 90%.

5. Earthquake horizontal acceleration: not more than 0.4m/s, vertical acceleration: not more than 0.2m/s.

6. There should be no conductive dust, corrosive, flammable, and explosive hazardous materials harmful to metals and insulation. It helps to ensure the external safety of the box-type substation.

7. There is no severe vibration at the installation site, and the vertical gradient is not more than 3 degrees. In order to facilitate the stability of the distribution box in the power station.

ten. Heat dissipation requirements of distribution box

The upper limit of the ambient temperature of electrical equipment designed and manufactured according to international standards during operation should not exceed 40°C. Sometimes the temperature inside the box is reached due to the direct sunlight, the reflection of heat from the cement floor and the heat generated by the equipment in the box. 60°C. Such a high temperature can easily cause the insulation of the electrical coils and leads in the distribution box to breakdown and burn; the electrical contacts increase the contact resistance due to the high temperature, and the increase of the contact resistance increases heating. Such a vicious cycle will eventually lead to power distribution The box contact burns out; at the same time, too high temperature will affect the stability of the electrical protection function, the reliability of the action, and the accuracy of measurement. Suggestions for this:

1. A distribution box with shutters on both sides and an incomplete separation in the center should be used as much as possible to form air convection heat dissipation;

2. The box body of the distribution box is made of essential stainless steel as much as possible, which is not easy to rust and has heat reflection. If the paint with heat insulation function can be sprayed on schedule to reduce heat radiation, the effect will be more ideal;

3. In addition to maintaining ventilation, the cabinet should be as far away as possible from direct sunlight at noon, and the ground should be non-gravel;

4. Avoid long-term operation of the equipment in the hot season, and reduce the heat released by the equipment in the distribution box as much as possible.