What are the three main parts of the leakage switch?

The composition of the current type leakage protector is divided into four parts:

1.Detection element: The detection element can be said to be a zero-sequence current transformer.

The protected phase wire and neutral wire pass through the annular core, constituting the primary coil N1 of the transformer, and the winding wound on the annular core constitutes the secondary coil N2 of the transformer, if there is no leakage, the sum of the current vectors flowing through the phase wire and the neutral wire is equal to zero, so the corresponding induced electromotive force can not be generated on N2. If leakage occurs, the sum of the current vectors of the phase and neutral wires is not equal to zero, so that the induced electromotive force is generated on the $, and this signal will be sent to the intermediate link for further processing.

2.Intermediate link: The intermediate link usually includes an amplifier, a comparator, a tripper, and when the intermediate link is electronic, the intermediate link also needs an auxiliary power supply to provide the power supply required for the work of the electronic circuit.

The function of the intermediate link is to amplify and process the leakage signal from the zero sequence transformer, and output it to the actuator.

3.Actuator: This structure is used to receive the command signal of the intermediate link, implement the action, and automatically cut off the power supply at the fault place.

4.Test device: Since the leakage protector is a protective device, it should be regularly checked whether it is intact and reliable. The test device simulates the leakage path through the series connection of the test button and the current limiting resistor to check whether the device can operate normally.

Housing, automatic air switch assembly's leakage detection assembly three parts.

The leakage protector is an important safety switch installed in the electrical circuit to ensure the safety of electricity, and can quickly and reliably cut off the power supply when the electrical equipment or line leaks and causes an electric shock accident to protect personal safety. The commonly used leakage protector is mainly composed of circuit breaker and leakage detection protection device, with short circuit, overload, leakage protection function, let's take a look at its specific structure and working principle.

Internal structure of the circuit breakerWhen the overload or short circuit of the line equipment occurs, the thermal overload element bends and deforms to trigger the action of the mechanical trip device, cutting off the electrical equipment line and playing a protective role.

The internal structure of the leakage detection protection deviceThe leakage detection and protection device is relatively complex, mainly composed of zero sequence current transformer (detection), signal circuit control board (signal current drive amplification), and trip coil (trip drive mechanism).

Zero sequence current transformer: The zero sequence current transformer is a detection mechanism for the protection device, which is composed of a magnetic core and a secondary winding coil. The electrical main circuit is interspersed with the magnetic core coil, and the sum of the current vector is zero when the line is working normally (the current value of the line passing through the transformer coil cancels each other out and does not produce a magnetic field), and the secondary coil will not produce an induced voltage, and when the sum of the line current vector is not zero, the secondary winding will generate an induced voltage to the signal circuit board for processing.

Signal circuit control board: The signal control board mainly processes the signal voltage from the zero sequence transformer, mainly including the rectification and drive amplification circuit, and outputs it to the trigger pole of the thyristor through the circuit board rectification, if the thyristor conduction condition is reached, the thyristor conduction provides working voltage to the tripper coil.

Trip coil: The trip coil is the actuator of the leakage protector, which is connected to the circuit breaker trip device through a mechanical connecting rod. When the tripper coil is energized, the coil generates a magnetic field force to drive the armature action, and the armature is connected with the connecting rod to drive the circuit breaker tripping device to cut off the electrical circuit equipment.

The specific working principle of the leakage protector is: when the equipment and line leakage cause an electric shock accident, the electrical circuit will produce two working circuits, one is the normal working circuit, and the other is the leakage electrical circuit. The leakage circuit current route passes through the live wire, the electrocution object, and the earth to form a loop, because the earth does not pass through the zero sequence transformer, at this time, the zero sequence transformer current vector sum is not zero (the current value is the leakage current value), the secondary winding generates an induced voltage through the drive board to trigger the thyristor conduction, the tripper coil is energized to work, and the armature is tripped and protected by the tripping mechanism driven by the connecting rod.

In the actual use of the leakage protector due to the different specifications of the protection object has a certain difference, in the process of use we should regularly test the leakage protection function (once a month), by pressing the test button to see whether the leakage protector can operate reliably to judge its quality, in order to ensure the integrity and reliability of its protection function!

The leakage protector is mainly composed of three parts: the detection element, the intermediate amplification link, and the operation actuator.

When the electrical equipment is in normal operation, the current in the line is in a balanced state, and the sum of the current vectors in the transformer is zero (the current is a vector with a direction, such as the direction of outflow is " " return direction " " in the transformer and the current in the transformer is equal in size, the direction is opposite, and the positive and negative cancel each other). Since there is no residual current in the primary coil, the secondary coil is not induced, and the switchgear of the leakage protector is operated in a closed state.

When the leakage of the equipment shell occurs and someone touches it, a shunt is generated at the fault point, and the leakage current returns to the neutral point of the transformer (without the current transformer) through the human body-earth-working grounding, resulting in an imbalance in and out of the transformer (the sum of the current vectors is not zero), and the residual current is generated by the primary coil. Therefore, the secondary coil will be inducted, and when this current value reaches the operating current value limited by the leakage protector, it will automatically switch and trip, and cut off the power supply.

The internal structure consists mainly of three parts. These three parts are the zero-sequence current transformer, the tripping coil, and the signal circuit control board. The working principle is that when there is a short circuit in the line, the trip coil will be bent and deformed, and then the device will be tripped.

It mainly includes three parts, one of which is to detect the original, and then also includes the operation execution, and the last one is the amplification process in the middle, which works on the principle that the circuit will be connected, and then the circuit will be controlled.

Circuit breaker, leakage detection protection, composition, leakage detection protection until leakage has been detected, the circuit breaker will actively cut off the power, which can effectively avoid physical injury.

The leakage protection stool is composed of () parts.

a.Zero-sequence current excavation travel transformer.

b.Leakage dissipation tripper.

c.Switchgear.

d.Voltage transformer.

e.Comparators.

Correct answer: ABC

Answer]: B leakage switch is divided into switch type, relay number divider spring outing type, single type leakage protector, combined leakage protector according to the type of work. The combined leakage protector is a combination of leakage switch and low-voltage circuit breaker.

According to the structural principle, it is divided into voltage action type, current type, phase detection type and pulse type.

The principle of the leakage switch is: there are two windings on one core, the main winding and the secondary winding. The main winding also has two ears, which are the input current winding and the output current winding.

When there is no leakage, the input current and the output current are equal, and the vector sum of the two magnetic fluxes on the core is zero, and the electric potential will not be induced on the secondary winding, otherwise the secondary winding will be induced by the voltage shape, and the actuator will be pushed by the amplifier to trip the switch. Regardless of whether it is a three-phase or single-phase leakage switch, the upper line is incoming and the bottom is outgoing.

The starting control of the leakage protector is realized by controlling a switch to be disconnected, and it cannot guarantee that the switch contact can be disconnected when there is a short circuit in the entire power supply circuit.

When it comes to leakage switches, many people will not be unfamiliar, but if you really want to tell you why it is and accurately tell what the leakage switch is, it still confuses many people. Today, I will tell you what a leakage switch is.

What is a leakage switch.

The leakage switch is mainly used to prevent the occurrence of leakage accidents, and the operating principle of the switch is: there are two windings on an iron core, the main winding and the auxiliary winding. The main winding also has two windings:

They are the input current winding and the output current winding. When there is no leakage, the input current and the output current are equal, and the vector sum of the two magnetic fluxes on the iron core is zero, and the electric potential will not be induced on the secondary winding, otherwise the voltage will be induced on the secondary winding, and the actuator will be pushed by the amplifier to trip the switch.

How to connect the leakage switch. The phase leakage switch is a three-phase four-wire hail system is commonly used today, three live wires (red, green, yellow), a neutral wire (blue), the voltage between the three live wires is 380 volts, and the voltage between each live wire and the neutral wire is 220 volts. The single-phase leakage switch is generally at the wiring, with left zero and right fire, just follow the connection.

Regardless of whether it is a three-phase or single-phase leakage switch, the upper line is incoming and the bottom is outgoing.

Leakage switch principle.

The principle of action of the leakage protection switch is: there are two groups on an iron core: an input current winding and an output current winding, when there is no leakage, the input current and the output current are equal, and the vector sum of the two magnetic fluxes on the iron core is zero, and the potential of the slow sail should not be felt on the third winding, otherwise the voltage will be induced on the third winding, and the actuator will be driven by amplification to trip the switch.

During normal operation, there is no leakage current in the circuit except for the working current through the leakage protector, at this time, the current flowing through the zero sequence transformer (detection transformer) is equal, the direction is opposite, the sum is zero, the induced magnetic flux in the core of the transformer is also equal to zero, the secondary winding has no output, the automatic switch is kept in the ON state, and the leakage protector is in normal operation. When the protected electrical appliances and the line leakage or someone is electrocuted, there is a grounding fault current, so that the amount of current flowing through the detection transformer is not zero, the magnetic flux is induced in the core of the transformer, and the secondary winding has an induced current, which is amplified and output, so that the leakage tripper action pushes the automatic switch to trip to achieve the purpose of leakage protection.

After reading the introduction of what the leakage switch is, do you have a comprehensive understanding of this product category?

The measurement part --- zero-sequence current transformer. It is used to sense unbalanced currents (leakage currents).

Amplification circuits --- used to amplify tiny leakage currents.

The tripping mechanism --- amplified current through the electromagnet to generate suction, attract the armature, and make the mechanism open.

The closing mechanism --- manually pushed up, and the hook is hung to maintain the closing.

The test circuit --- press the button, the electromagnet is energized, and the switch can be tested.

Enclosures and binding posts, needless to say.

Under normal circumstances, the three-phase load current and the leakage current to the ground are basically balanced, and the phasor sum of the current flowing through the primary coil of the transformer is about zero, that is, the total magnetic flux generated by it in the core is zero, and the secondary coil of the zero-sequence transformer has no output. When an electric shock occurs, the electrocution current passes through the earth into a loop, that is, a zero-sequence current is generated. This current does not flow back through the transformer's primary coil, which destroys the balance, so there is a zero-sequence magnetic flux in the core, which makes the secondary coil output signal.

This signal is amplified and judged by comparing the elements, and if the predetermined action value is reached, the execution signal will be sent to the action of the actuator and the power supply will be cut off.

To put it simply, it is a current sensor, once the current is too large, or the current of the neutral line and the live wire is not equal, the gate will be pulled immediately.