Whether overhead incoming wires or cable incoming wires are used in the high-voltage side of the high-voltage and low-voltage distribution cabinets, obvious fractures (such as drop fuses, etc.) should be set near the substation. So as to clearly show the maintenance operator whether the substation is electrified or not. So as to ensure the safety of maintenance operators. Reliable grounding should be done after the product is installed in place: the two main grounding terminals on the channel steel of the power station base, the neutral point and shell of the transformer, and the lower pile head of the lightning arrester should be directly grounded by the installation department respectively. The grounding device should share a group of grounding devices, the grounding resistance should be less than 4 ohms, and there should be no less than two grounding leads leading from the grounding network to this product.
The safe use of high and low voltage distribution cabinets has always been the focus of attention, so which ones are worthy of our attention in the use process? According to the research of professionals in high and low voltage power distribution cabinets, the following four matters need to be understood. When working on all or part of the live disk, the maintenance equipment should be separated from the operating equipment with obvious signs. The secondary winding with current transformer and voltage transformer should be permanently and reliably grounded. When working on the secondary circuit of the running current transformer, it is forbidden to disconnect the current circuit.
In order to reliably short-circuit the secondary coil of current transformer, short-circuit pieces and short lines must be used, and wire winding is prohibited. It is forbidden to do any work on the circuit and wires between the current transformer and the short-circuit terminal. Strictly prevent short circuit or grounding when working on the secondary circuit of voltage transformer in operation. Insulating tools and gloves should be used, and relevant relay protection devices should be stopped before working if necessary. When connecting temporary loads, special switches and fuses must be installed. When the secondary circuit is electrified, in order to prevent the secondary side from being transformed reversely at one time, in addition to disconnecting the secondary circuit, the primary fuse should be removed. Before the secondary circuit is electrified or subjected to withstand voltage test, the attendant and relevant personnel shall be informed, and people shall be sent to guard the site, check the circuit and confirm that no one is working before pressurizing. The staff who check the power-off protection and secondary circuit are not allowed to perform any switching operation without the permission of the duty officer.
Recently, I found a problem, that is, after the customer bought the power distribution cabinet, the power distribution cabinet manufacturer sent the goods to the site, and the customer didn’t know how to inspect the goods. The problems all appeared in the process of use, causing unnecessary trouble to both parties, so here is how to inspect the power distribution cabinet today.
First of all, look at the inspection. For the unpacked distribution cabinets, carefully check the quantity and specifications according to the design drawings and imitation sheets, check whether they meet the requirements, whether they are damaged or rusted, and check whether the accessories and spare parts are complete. After unpacking, check the factory certificate, copy sheet and internal wiring diagram and other technical documents. After unpacking the high-voltage distribution cabinets, number the distribution cabinets according to the design drawings and move them into the installation position in the substation in sequence.
After the power distribution cabinet is placed on the channel steel, the high-voltage cabinet should be roughly leveled with a thin pad iron, and then the rest should be adjusted based on one of them, so that all the high-voltage cabinets have a uniform gap. After the bolts are fixed, the 213~ # gap is maintained between cabinets, and finally the cabinets are fixed on the foundation channel steel forever by fixing bolts or welding. For the sake of beauty, the weld should be welded on the inside of the cabinet, and there should be no less than 4 places, each with a length of 801,100 ~.
Connect the bus. The main bus and instruments on the power distribution cabinet are provided by Kai Guanchang, and can also be made according to the design drawings at the construction site. The connection of the main bus, the connection between the main bus and the down bus, and the connection between the bus and the instrument shall be connected by bolts, and the connection surface of the bus shall be coated with electric compound grease. The tightening degree of the bolts and the connection condition of the connection surface shall be controlled by tightening the bolts with a torque wrench according to the specified torque value.
Installation of handcart distribution cabinet. The installation method is basically the same as the fixed cabinet, but the difference is to ensure the interchangeability of handcart. Each handcart-type moving contact must be adjusted by 1, and the center of the moving and static contacts must be adjusted by 1 and contacted closely to ensure interchangeability. Check the plug and auxiliary contacts of the secondary circuit of the power distribution cabinet for reliable welding. The electrical or mechanical locking device is correct, so that the handcart cannot be pulled out when it is in the closing position. The safety partition can be easily opened and closed, and can move with the entrance and exit of the car. The contact between the grounding device of handcart and the fixed frame of distribution cabinet should be excellent. The restraint cable in the cabinet is firmly fixed, which does not affect the movement of the handcart.
The laying of maintenance grounding branch lines for electrical equipment, appliances and non-live metal parts shall meet the following requirements: the connection shall be tight and firm, the section of maintenance grounding line shall be selected correctly, and the parts to be protected from corrosion shall be painted evenly without omission. The route is fair, the color code is accurate, and the equipment and buildings will not be polluted after painting. Check the "5-proof" interlock of the power distribution cabinet, which is fully functional and reliable.