What is the essential difference between leakage current and residual current?

1. Leakage current is a kind of residual current, and the meaning of residual current covers leakage current;

2. From the perspective of the working principle of protection, the leakage protector and the residual current protector are exactly the same, and it is more reasonable to call the residual current protector, because not only the leakage makes the protector act, but also the three-phase unbalance and harmonic current will also make the protector act;

3. The residual current is translated according to the IEC standard, and there is no definition of leakage current;

4. Most of the domestic manufacturers have changed their names to residual current action protection devices, and some still use the name of leakage protectors.

Residual current. Excess current, residual current According to the statistics of the fire department, in the national fire accidents, electrical fires account for about 1 3, and in electrical fire accidents, due to the single-phase grounding fault of low-voltage lines, the accidents account for about 1 2 of electrical fire accidents. It can be seen that the severity and prevalence of single-phase grounding faults of the line.

There are many reasons for single-phase ground faults in the line.

Leakage current: Leakage current is generated by a certain potential difference between the electrical shell and the mains fire wire after being connected for some reason. The best way to detect leakage is to use a pen to contact the charged body, if the neon bubble is lit up and immediately extinguished, it proves that the charged body is static electricity; If it is always bright, it must be leakage.

The landlord is talking about several parameters of the electrical leakage protection circuit breaker.

The rated leakage current is when the leakage current is reached, and the leakage protector starts to act.

The rated leakage current is less than this leakage current, and the leakage protector cannot operate.

The leakage protection switch only reflects the residual current of the system, the residual current of the system is almost zero during normal operation, in the event of leakage or electric shock accident, the circuit produces residual current, the initial value is generally small, so its action value can be set very small, and in the system grounding fault occurs a large residual current, the leakage protection switch can act reliably and cut off the power supply.

So I don't think there is a situation where I think I give it a 20mA current, and the reaction time from 15mA to 30mA is relatively short, and there is a 20mA stage in which it has passed.

Leakage current is the current generated by the power supply and other objects that should not be energized instead of passing through the load, such as the ground current caused by poor insulation, and the current generated by the equipment housing due to moisture. This is a very dangerous electric current that can immediately form a circuit when a person comes into contact with the enclosure of the device. If the voltage is high, it is very dangerous.

Therefore, on the one hand, the family is installed with a leakage protector, and once the leakage current is less than 36mA, it will trip.

First, the nature is different.

1. Leakage protection: When the leakage current of the power grid exceeds a certain set value, it can automatically cut off the power supply or send out an alarm signal.

2. Residual current protection: It is an effective protective measure to prevent personal electric shock, electrical fire and damage to electrical equipment.

Second, the basic principles are different.

1. Leakage protection: The principle of leakage protection used for underground power grid mainly includes the following types: additional DC power supply principle, zero sequence voltage principle, zero sequence current principle, zero sequence current direction principle (also called zero sequence power direction principle), harmonic current direction principle and additional intermediate frequency power supply principle.

2. Residual current protection: the iron core wraps all the current-carrying conductors of an electrical circuit, and the magnetic flux generated in the magnetic core is related to the arithmetic sum of these conductor currents in an instant; If the current flowing in one direction is assumed to be positive (i1), then the current flowing in the opposite direction is negative (i2).

In a fault-free normal circuit i1 + i2 = 0, there is no magnetic flux inside the core and the electromotive force inside the coil is zero. The ground fault current ID flows through the core to the point of fault, but returns to power via ground or through the protection line of the TN system. As a result, the current passing through the conductors of the core is no longer balanced, and the current difference generates a magnetic flux within the core.

Third, the characteristics are different.

1. Leakage protection: In the event of leakage failure, if it is not protected in time, it will have serious consequences, especially in the underground coal mine; may cause danger to human life; It may cause gas and coal dust; It may ignite the detonator in advance; For neutral grounding systems and neutral non-grounding systems with large distributed capacitance, it is possible that the one-phase windings of the motor will burn out.

2. Residual current protection: The residual current action protector can only play a protective role when a single-phase electric shock accident occurs in the human body. If the human body is in an insulated state to the ground, once it touches two phase wires or a phase wire and a neutral wire, the protector will not act, that is, it will not play a protective role at this time.

As for the leakage current, it is actually the current that can be measured by the instrument after applying a specified voltage to two measurement points. As for the formula, I've never read about it in a book.

Leakage current is an electrical parameter that is automatically generated when a specified voltage is applied to the object to be measured. In my personal understanding, the resistance value of any item is not infinitely large, and at the same time, after the resistance value of this item exceeds a certain voltage value, the resistance value will become smaller, and even become a short circuit.

Regarding the determination of leakage current, there are relevant product technical standards to stipulate, and relevant detection methods are also specified. My personal understanding is that the determination of the leakage current index should be related to the human body's ability to withstand the current, which is a safety indicator.

At the same time, we should have a concept, that is, in reality, the relationship between the voltage and current of the product is not linear, and there is also a limit to withstand the voltage, after exceeding, the original correspondence between voltage and current will no longer exist.

As for the formula for calculating leakage current, it can actually be understood by the most basic formulas of resistance, voltage and current, except that this resistance value is not constant and has a maximum voltage limit.