Eight precautions for power cords

2023-05-25 10:01:48

1. Classification of Insulated Wires

Answer: There are several types of insulated wires commonly used, including polyvinyl chloride insulated wires, polyvinyl chloride insulated flexible wires, nitrile polyvinyl chloride mixture insulated flexible wires, rubber insulated wires, agricultural underground buried aluminum core plastic insulated wires, rubber insulated cotton yarn textile flexible wires, polyvinyl chloride insulated nylon sheathed wires, and polyvinyl chloride insulated flexible wires for power and lighting.

2. What occasions are cable trays suitable for?

Answer: Cable trays are suitable for overhead laying of power cables and control cables indoors and outdoors in general industrial and mining enterprises. They can also be used for indoor and outdoor installation in telecommunications, broadcasting and television departments.

3. Types of cable accessories

Answer: Common electrical accessories include cable terminal junction boxes, cable intermediate junction boxes, connecting pipes and terminals, steel plate wiring troughs, cable trays, etc.

4. The meaning of cable intermediate joint

Answer: The device that connects the conductors, insulation shielding layers, and protective layers of cables to connect cable lines is called a cable intermediate joint.

5. What is an electrical main connector?

Answer: The main electrical wiring is the connection method of the main electrical equipment and busbar in power plants and substations, including the connection method of the main busbar and the plant power system according to certain functional requirements.

6. What regulations should be followed when selecting the cross-section of power cables?

Answer: The selection of power cables should follow the following principles:

(1) The rated voltage of the cable should be greater than or equal to the rated voltage of the power supply system at the installation point;

(2) The continuous allowable current of the cable should be equal to or greater than the maximum continuous current of the power supply load;

(3) The cross-sectional area of the wire core should meet the stability requirements of the power supply system during a short circuit;

(4) Verify whether the voltage drop meets the requirements based on the length of the cable;

(5) The minimum short-circuit current at the end of the line should enable the protection device to operate reliably.

7. What are the advantages of cross-linked polyethylene cables compared to oil paper cables?

Answer:

(1) Easy to install because it allows for a small minimum bending radius and is lightweight;

(2) Not limited by line drop;

(3) Good thermal performance, allowing for high operating temperatures and large transmission capacity;

(4) The cable accessories are simple and all of them are dry-type structures;

(5) Easy operation and maintenance, no oil leakage issues;

(6) Low price;

(7) High reliability and low failure rate;

(8) The manufacturing process is few, the technology is simple, and the economic benefits are significant.

8. What are the requirements for fixtures for fixed AC single core cables? Why?

Answer: The fixture should have no iron parts to form a closed magnetic circuit. This is because when the cable core passes through current, magnetic lines are generated around it, and the magnetic lines are proportional to the current passing through the core. If magnetic materials such as iron parts are used, according to electromagnetic induction, eddy currents will be generated in the iron parts, causing the cable to heat up and even burn out. So iron parts cannot be used as fixing fixtures for single core AC cables.