The protective role of low-voltage power distribution systems

Today, Guangxi High and Low Voltage Distribution - Senge Technology will talk to you about the protective role of low-voltage power distribution systems.

1. Short circuit protection

Short circuit protection requires cutting off the faulty circuit before the short-circuit current generates significant thermal effects and electrical hazards to the conductors and connectors, i.e. requiring the switchgear to trip for a short period of time or instantaneously.

2. Overload protection

When an overload fault occurs, the insulation, joints, terminals, and surrounding materials of the wire should be cut off before the overload current causes damage to the insulation, joints, terminals, and surrounding materials of the conductor. However, for sudden cuts that would cause significant losses, only an alarm will be given and the power circuit will not be cut off.

Overload has a process of heat accumulation, and the protection action does not need to be too fast because the protection should not be activated due to short-term overcurrent.

In addition, attention should be paid to adjusting the protection setting value in a timely manner after load changes, to prevent frequent tripping that affects power supply quality if the setting value is too small, or if the setting value is too large, causing ineffective protection for the line and equipment.

3. Ground fault protection

The most important measure to prevent personal indirect electric shock and line damage, even causing accidents such as electrical fires and houses, is to set up ground fault protection. There are two types of leakage protection devices: thermal magnetic and electronic. In contrast, electronic drain devices have the advantages of small size, high accuracy, and high sensitivity, but their anti-interference ability is poor.

At present, electronic leakage protectors dominate the market. When the leakage current reaches the set value, the executing circuit receives the induced voltage signal from the secondary side of the zero sequence current transformer, drives the conversion contact to output the leakage current to reach the set value, receives the induced voltage signal from the secondary side of the zero sequence current transformer, drives the conversion contact to output the leakage protection signal, and cuts off the power supply of the release.

The set leakage current of general terminal switches is 30mA, used to protect personal safety; The setting value of the superior branch switch is 300mA, used to protect equipment safety. Due to the leakage current value being much lower than the normal working current value, the short-circuit protection or overload protection function cannot detect the fault current, and the fault circuit cannot be cut off. The leakage protection device can reliably cut off the ground fault, preventing personal electric shock and phase to ground short circuit faults.

Guangxi High and Low Voltage Distribution - Senge Technology reminds us that the protection and coordination of low-voltage distribution systems are very important links in low-voltage distribution systems, and also a very important factor in ensuring the stable and reliable operation of power systems.

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