There are several main factors that cannot be directly grounded at both ends of single-core cables:
1. Circulation problem: If both ends of a single-core cable are directly grounded, a large circulation may occur in the cable, because the shielding layer of the cable forms a closed loop with the ground. This circulation will not only increase line loss, but may also cause cable overheating and reduce the service life of the cable.
2. Electromagnetic compatibility issues: If a single-core cable is directly grounded, it may become a carrier of electromagnetic interference, affecting the stability of the cable transmission signal, especially in high-voltage or high-frequency transmission occasions.
3. Potential increase: When one end of a single-core cable is grounded and the other end is grounded, the potential at the other end of the cable will increase to twice the system voltage, increasing the electric field strength of the cable insulation layer, which may lead to insulation breakdown.
4. Insulation problem: If there are defects in the insulation layer of the cable, grounding at both ends may accelerate insulation aging and increase the risk of cable failure.
5. System protection problem: For some protection devices, grounding at both ends of single-core cables may affect the correct action of the protection device, causing the system protection function to fail.
6. Ground potential difference: At different ground points, there may be differences in ground potential, which may cause current to flow through the ground wire, causing unnecessary losses and interference.
To resolve these problems, the following measures are usually adopted:
Use a cable with a good insulation layer and install the insulated connectors in place. Use a single point grounding method to avoid the formation of closed loops.
Install suitable protection devices, such as cable guard protectors, in the cable circuit to prevent overvoltage of the cable shield. When designing cable lines, consider electromagnetic compatibility issues and take measures such as shielding and filtering. These measures help ensure the safe and stable operation of the cable system.
