How does protect personal safety?
In this age of electricity everywhere, there are few safety measures to use electricity. is one of them, and it is also necessary for the safety of household electricity. It is closely related to our life, so we publish a chapter about leakage protection here, hoping that you can have a general understanding of this.
Leakage protector, also known as leakage switch, as the name implies, it is a kind of leakage sensitive and action switch. The basic leakage protection is divided into three parts: leakage detection, signal processing and actuator. The leakage detection part is a zero sequence current transformer. The phase line and zero line pass through the primary side of the transformer from the middle of the magnetic ring, and the winding coil on the magnetic ring is the secondary side. Under normal circumstances, the current flowing out of the phase line and the current flowing back from the zero line are equal, but the direction is opposite In case of leakage of equipment or lines, leakage current will bypass the working circuit and flow directly to the earth, resulting in unbalanced internal current of the transformer, generating residual current. The induced signal at the secondary side is sent to the signal processing circuit, and the leakage signal is processed or compared with each other When a certain value is reached, it will be sent to the release of the actuator, which will cut off the power supply and protect the safety of power consumption.
Generally, the shell of household electrical appliances is grounded. Under normal circumstances, the shell is not electrified. However, if the equipment fails and the insulation of internal circuit and shell is damaged, the shell is electrified. The leakage current will flow to the earth through the shell of the machine. If the leakage protector detects that there is leakage failure, it will cut off the power switch to prevent personal touching the shell of the machine from electric shock.
Someone will ask, if there is no ground wire in the home circuit, is leakage protector ineffective? I remember that I was asked this question a few days ago, and I'm here to answer it. Leakage protector and ground wire belong to two different protection measures. If the family does not check the ground wire, when the electric equipment leaks, the case does not ground to form leakage current, the leakage protector will not act. Only when the person touches the leakage electric equipment, the current will flow through the human body to the earth, forming leakage current, and the leakage protector will trip, so it is grounded or not The grounding wire and leakage protector will work, but it is only the problem before and after the human body gets electric shock. To be clear, when there is no grounding, only when the human body is electrified can it trip. Therefore, for the sake of safety, it is better to use both protection measures.
In addition, there is a special case that electric shock will not cause the leakage protector to act. That is, when the human body touches the live line and the zero line at the same time and is insulated from the earth, the leakage protector will not trip. At this time, the human body is equivalent to a load. The current flowing on the transformer and the current flowing back are equal, and there is no residual current, so it will not Trigger the action of tripper. It's very dangerous to get electric shock in this case, so you need to pay attention to it. Don't touch any electrified body if you are OK.
