Reasons for refusing to act
When the protection line passes through the zero-sequence current transformer, the leakage current will return through the zero-sequence current transformer after passing through the protection line, resulting in current phase cancellation, and at the same time, the leakage current value cannot be detected on the transformer, which will lead to equipment failure and cause the leakage protector to refuse to operate.
The working neutral wire and protection wire behind the leakage protector cannot be combined into one. If they are combined into one, when there is a leakage fault or human body gets an electric shock, the leakage current will flow back through the current transformer, causing the leakage protector to refuse to operate. The internal component failure and internal component defect of the leakage protection device will cause the leakage protection device to refuse to work. If the protective wire is also connected to the leakage protection device, it is wrong, which will also cause the leakage protection device to refuse to operate. Whether the equipment is equipped with RCD or not, and at the same time * * * uses the same grounding device, it will also cause the leakage protector to refuse to operate and lose its protection function. In this case, according to the site conditions, the distance between the two grounding bodies should be far apart and grounded separately.
4. Preventive measures for misoperation and refusal of leakage protector
When installing the leakage protector, we should pay attention to distinguish between the working zero line and the protection zero line. The working zero line passing through the leakage protector cannot be used as the protection zero line. The working zero line should be connected to the leakage protector, passing through the zero-sequence current transformer of the leakage protector, and cannot be repeatedly grounded or connected to the shell of mechanical equipment. In the construction site with high temperature, high humidity, heavy metal ratio or good conductivity, an independent leakage protector must be used, and one leakage protector must never be used to protect two or more mechanical equipment. After installing the leakage protector, check whether the equipment is correct, and operate the test button to check whether the action is normal. Only when everything is normal can it be put into use. Leakage protectors that do not meet the use and safety requirements must be scrapped and destroyed, and no other unit or individual may recycle them to avoid potential safety hazards.
In lightning-prone areas, if electrical equipment needs to be equipped with leakage protectors, electromagnetic leakage protectors with fixed impulse voltage should be selected. When the leakage protector is put into normal operation, the sensitivity and reliability of the protector should be tested frequently when it is energized, and whether the parameters change in time. If necessary, the leakage protector with hidden dangers should be replaced.
There are many comprehensive factors leading to misoperation and refusal of leakage protector, so it is necessary to correctly select and configure safety leakage protector, reasonably connect wires, and check the safety of equipment in time to ensure that there are no potential safety hazards during use. Strengthen the management of unplanned external electricity in the construction site, or improve the professional skills and safe operation methods of equipment users through systematic and professional training, and raise the awareness of safety precautions, thus reducing the possibility of misoperation and refusal of equipment.